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Based on kernel version 4.7.2. Page generated on 2016-08-22 22:45 EST.

1	  <title>Image Formats</title>
2	
3	  <para>The V4L2 API was primarily designed for devices exchanging
4	image data with applications. The
5	<structname>v4l2_pix_format</structname> and <structname>v4l2_pix_format_mplane
6	</structname> structures define the format and layout of an image in memory.
7	The former is used with the single-planar API, while the latter is used with the
8	multi-planar version (see <xref linkend="planar-apis"/>). Image formats are
9	negotiated with the &VIDIOC-S-FMT; ioctl. (The explanations here focus on video
10	capturing and output, for overlay frame buffer formats see also
11	&VIDIOC-G-FBUF;.)</para>
12	
13	<section>
14	  <title>Single-planar format structure</title>
15	  <table pgwide="1" frame="none" id="v4l2-pix-format">
16	    <title>struct <structname>v4l2_pix_format</structname></title>
17	    <tgroup cols="3">
18	      &cs-str;
19	      <tbody valign="top">
20		<row>
21		  <entry>__u32</entry>
22		  <entry><structfield>width</structfield></entry>
23		  <entry>Image width in pixels.</entry>
24		</row>
25		<row>
26		  <entry>__u32</entry>
27		  <entry><structfield>height</structfield></entry>
28		  <entry>Image height in pixels. If <structfield>field</structfield> is
29		  one of <constant>V4L2_FIELD_TOP</constant>, <constant>V4L2_FIELD_BOTTOM</constant>
30		  or <constant>V4L2_FIELD_ALTERNATE</constant> then height refers to the
31		  number of lines in the field, otherwise it refers to the number of
32		  lines in the frame (which is twice the field height for interlaced
33		  formats).</entry>
34		</row>
35		<row>
36		  <entry spanname="hspan">Applications set these fields to
37	request an image size, drivers return the closest possible values. In
38	case of planar formats the <structfield>width</structfield> and
39	<structfield>height</structfield> applies to the largest plane. To
40	avoid ambiguities drivers must return values rounded up to a multiple
41	of the scale factor of any smaller planes. For example when the image
42	format is YUV 4:2:0, <structfield>width</structfield> and
43	<structfield>height</structfield> must be multiples of two.</entry>
44		</row>
45		<row>
46		  <entry>__u32</entry>
47		  <entry><structfield>pixelformat</structfield></entry>
48		  <entry>The pixel format or type of compression, set by the
49	application. This is a little endian <link
50	linkend="v4l2-fourcc">four character code</link>. V4L2 defines
51	standard RGB formats in <xref linkend="rgb-formats" />, YUV formats in <xref
52	linkend="yuv-formats" />, and reserved codes in <xref
53	linkend="reserved-formats" /></entry>
54		</row>
55		<row>
56		  <entry>&v4l2-field;</entry>
57		  <entry><structfield>field</structfield></entry>
58		  <entry>Video images are typically interlaced. Applications
59	can request to capture or output only the top or bottom field, or both
60	fields interlaced or sequentially stored in one buffer or alternating
61	in separate buffers. Drivers return the actual field order selected.
62	For more details on fields see <xref linkend="field-order" />.</entry>
63		</row>
64		<row>
65		  <entry>__u32</entry>
66		  <entry><structfield>bytesperline</structfield></entry>
67		  <entry>Distance in bytes between the leftmost pixels in two
68	adjacent lines.</entry>
69		</row>
70		<row>
71		  <entry spanname="hspan"><para>Both applications and drivers
72	can set this field to request padding bytes at the end of each line.
73	Drivers however may ignore the value requested by the application,
74	returning <structfield>width</structfield> times bytes per pixel or a
75	larger value required by the hardware. That implies applications can
76	just set this field to zero to get a reasonable
77	default.</para><para>Video hardware may access padding bytes,
78	therefore they must reside in accessible memory. Consider cases where
79	padding bytes after the last line of an image cross a system page
80	boundary. Input devices may write padding bytes, the value is
81	undefined. Output devices ignore the contents of padding
82	bytes.</para><para>When the image format is planar the
83	<structfield>bytesperline</structfield> value applies to the first
84	plane and is divided by the same factor as the
85	<structfield>width</structfield> field for the other planes. For
86	example the Cb and Cr planes of a YUV 4:2:0 image have half as many
87	padding bytes following each line as the Y plane. To avoid ambiguities
88	drivers must return a <structfield>bytesperline</structfield> value
89	rounded up to a multiple of the scale factor.</para>
90	<para>For compressed formats the <structfield>bytesperline</structfield>
91	value makes no sense. Applications and drivers must set this to 0 in
92	that case.</para></entry>
93		</row>
94		<row>
95		  <entry>__u32</entry>
96		  <entry><structfield>sizeimage</structfield></entry>
97		  <entry>Size in bytes of the buffer to hold a complete image,
98	set by the driver. Usually this is
99	<structfield>bytesperline</structfield> times
100	<structfield>height</structfield>. When the image consists of variable
101	length compressed data this is the maximum number of bytes required to
102	hold an image.</entry>
103		</row>
104		<row>
105		  <entry>&v4l2-colorspace;</entry>
106		  <entry><structfield>colorspace</structfield></entry>
107		  <entry>This information supplements the
108	<structfield>pixelformat</structfield> and must be set by the driver for
109	capture streams and by the application for output streams,
110	see <xref linkend="colorspaces" />.</entry>
111		</row>
112		<row>
113		  <entry>__u32</entry>
114		  <entry><structfield>priv</structfield></entry>
115		  <entry><para>This field indicates whether the remaining fields of the
116	<structname>v4l2_pix_format</structname> structure, also called the extended
117	fields, are valid. When set to <constant>V4L2_PIX_FMT_PRIV_MAGIC</constant>, it
118	indicates that the extended fields have been correctly initialized. When set to
119	any other value it indicates that the extended fields contain undefined values.
120	</para>
121	<para>Applications that wish to use the pixel format extended fields must first
122	ensure that the feature is supported by querying the device for the
123	<link linkend="querycap"><constant>V4L2_CAP_EXT_PIX_FORMAT</constant></link>
124	capability. If the capability isn't set the pixel format extended fields are not
125	supported and using the extended fields will lead to undefined results.</para>
126	<para>To use the extended fields, applications must set the
127	<structfield>priv</structfield> field to
128	<constant>V4L2_PIX_FMT_PRIV_MAGIC</constant>, initialize all the extended fields
129	and zero the unused bytes of the <structname>v4l2_format</structname>
130	<structfield>raw_data</structfield> field.</para>
131	<para>When the <structfield>priv</structfield> field isn't set to
132	<constant>V4L2_PIX_FMT_PRIV_MAGIC</constant> drivers must act as if all the
133	extended fields were set to zero. On return drivers must set the
134	<structfield>priv</structfield> field to
135	<constant>V4L2_PIX_FMT_PRIV_MAGIC</constant> and all the extended fields to
136	applicable values.</para></entry>
137		</row>
138		<row>
139		  <entry>__u32</entry>
140		  <entry><structfield>flags</structfield></entry>
141		  <entry>Flags set by the application or driver, see <xref
142	linkend="format-flags" />.</entry>
143		</row>
144		<row>
145		  <entry>&v4l2-ycbcr-encoding;</entry>
146		  <entry><structfield>ycbcr_enc</structfield></entry>
147		  <entry>This information supplements the
148	<structfield>colorspace</structfield> and must be set by the driver for
149	capture streams and by the application for output streams,
150	see <xref linkend="colorspaces" />.</entry>
151		</row>
152		<row>
153		  <entry>&v4l2-quantization;</entry>
154		  <entry><structfield>quantization</structfield></entry>
155		  <entry>This information supplements the
156	<structfield>colorspace</structfield> and must be set by the driver for
157	capture streams and by the application for output streams,
158	see <xref linkend="colorspaces" />.</entry>
159		</row>
160		<row>
161		  <entry>&v4l2-xfer-func;</entry>
162		  <entry><structfield>xfer_func</structfield></entry>
163		  <entry>This information supplements the
164	<structfield>colorspace</structfield> and must be set by the driver for
165	capture streams and by the application for output streams,
166	see <xref linkend="colorspaces" />.</entry>
167		</row>
168	      </tbody>
169	    </tgroup>
170	  </table>
171	</section>
172	
173	<section>
174	  <title>Multi-planar format structures</title>
175	  <para>The <structname>v4l2_plane_pix_format</structname> structures define
176	    size and layout for each of the planes in a multi-planar format.
177	    The <structname>v4l2_pix_format_mplane</structname> structure contains
178	    information common to all planes (such as image width and height) and
179	    an array of <structname>v4l2_plane_pix_format</structname> structures,
180	    describing all planes of that format.</para>
181	  <table pgwide="1" frame="none" id="v4l2-plane-pix-format">
182	    <title>struct <structname>v4l2_plane_pix_format</structname></title>
183	    <tgroup cols="3">
184	      &cs-str;
185	      <tbody valign="top">
186	        <row>
187	          <entry>__u32</entry>
188	          <entry><structfield>sizeimage</structfield></entry>
189	          <entry>Maximum size in bytes required for image data in this plane.
190	          </entry>
191	        </row>
192	        <row>
193	          <entry>__u32</entry>
194	          <entry><structfield>bytesperline</structfield></entry>
195	          <entry>Distance in bytes between the leftmost pixels in two adjacent
196	            lines. See &v4l2-pix-format;.</entry>
197	        </row>
198	        <row>
199	          <entry>__u16</entry>
200	          <entry><structfield>reserved[6]</structfield></entry>
201	          <entry>Reserved for future extensions. Should be zeroed by drivers and
202	           applications.</entry>
203	        </row>
204	      </tbody>
205	    </tgroup>
206	  </table>
207	  <table pgwide="1" frame="none" id="v4l2-pix-format-mplane">
208	    <title>struct <structname>v4l2_pix_format_mplane</structname></title>
209	    <tgroup cols="3">
210	      &cs-str;
211	      <tbody valign="top">
212	        <row>
213	          <entry>__u32</entry>
214	          <entry><structfield>width</structfield></entry>
215	          <entry>Image width in pixels. See &v4l2-pix-format;.</entry>
216	        </row>
217	        <row>
218	          <entry>__u32</entry>
219	          <entry><structfield>height</structfield></entry>
220	          <entry>Image height in pixels. See &v4l2-pix-format;.</entry>
221	        </row>
222	        <row>
223	          <entry>__u32</entry>
224	          <entry><structfield>pixelformat</structfield></entry>
225	          <entry>The pixel format. Both single- and multi-planar four character
226	codes can be used.</entry>
227	        </row>
228	        <row>
229	          <entry>&v4l2-field;</entry>
230	          <entry><structfield>field</structfield></entry>
231	          <entry>See &v4l2-pix-format;.</entry>
232	        </row>
233	        <row>
234	          <entry>&v4l2-colorspace;</entry>
235	          <entry><structfield>colorspace</structfield></entry>
236	          <entry>See &v4l2-pix-format;.</entry>
237	        </row>
238	        <row>
239	          <entry>&v4l2-plane-pix-format;</entry>
240	          <entry><structfield>plane_fmt[VIDEO_MAX_PLANES]</structfield></entry>
241	          <entry>An array of structures describing format of each plane this
242	          pixel format consists of. The number of valid entries in this array
243	          has to be put in the <structfield>num_planes</structfield>
244	          field.</entry>
245	        </row>
246	        <row>
247	          <entry>__u8</entry>
248	          <entry><structfield>num_planes</structfield></entry>
249	          <entry>Number of planes (i.e. separate memory buffers) for this format
250	          and the number of valid entries in the
251	          <structfield>plane_fmt</structfield> array.</entry>
252	        </row>
253		<row>
254		  <entry>__u8</entry>
255		  <entry><structfield>flags</structfield></entry>
256		  <entry>Flags set by the application or driver, see <xref
257	linkend="format-flags" />.</entry>
258		</row>
259		<row>
260		  <entry>&v4l2-ycbcr-encoding;</entry>
261		  <entry><structfield>ycbcr_enc</structfield></entry>
262		  <entry>This information supplements the
263	<structfield>colorspace</structfield> and must be set by the driver for
264	capture streams and by the application for output streams,
265	see <xref linkend="colorspaces" />.</entry>
266		</row>
267		<row>
268		  <entry>&v4l2-quantization;</entry>
269		  <entry><structfield>quantization</structfield></entry>
270		  <entry>This information supplements the
271	<structfield>colorspace</structfield> and must be set by the driver for
272	capture streams and by the application for output streams,
273	see <xref linkend="colorspaces" />.</entry>
274		</row>
275		<row>
276		  <entry>&v4l2-xfer-func;</entry>
277		  <entry><structfield>xfer_func</structfield></entry>
278		  <entry>This information supplements the
279	<structfield>colorspace</structfield> and must be set by the driver for
280	capture streams and by the application for output streams,
281	see <xref linkend="colorspaces" />.</entry>
282		</row>
283	        <row>
284	          <entry>__u8</entry>
285	          <entry><structfield>reserved[7]</structfield></entry>
286	          <entry>Reserved for future extensions. Should be zeroed by drivers
287	           and applications.</entry>
288	        </row>
289	      </tbody>
290	    </tgroup>
291	  </table>
292	</section>
293	
294	  <section>
295	    <title>Standard Image Formats</title>
296	
297	    <para>In order to exchange images between drivers and
298	applications, it is necessary to have standard image data formats
299	which both sides will interpret the same way. V4L2 includes several
300	such formats, and this section is intended to be an unambiguous
301	specification of the standard image data formats in V4L2.</para>
302	
303	    <para>V4L2 drivers are not limited to these formats, however.
304	Driver-specific formats are possible. In that case the application may
305	depend on a codec to convert images to one of the standard formats
306	when needed. But the data can still be stored and retrieved in the
307	proprietary format. For example, a device may support a proprietary
308	compressed format. Applications can still capture and save the data in
309	the compressed format, saving much disk space, and later use a codec
310	to convert the images to the X Windows screen format when the video is
311	to be displayed.</para>
312	
313	    <para>Even so, ultimately, some standard formats are needed, so
314	the V4L2 specification would not be complete without well-defined
315	standard formats.</para>
316	
317	    <para>The V4L2 standard formats are mainly uncompressed formats. The
318	pixels are always arranged in memory from left to right, and from top
319	to bottom. The first byte of data in the image buffer is always for
320	the leftmost pixel of the topmost row. Following that is the pixel
321	immediately to its right, and so on until the end of the top row of
322	pixels. Following the rightmost pixel of the row there may be zero or
323	more bytes of padding to guarantee that each row of pixel data has a
324	certain alignment. Following the pad bytes, if any, is data for the
325	leftmost pixel of the second row from the top, and so on. The last row
326	has just as many pad bytes after it as the other rows.</para>
327	
328	    <para>In V4L2 each format has an identifier which looks like
329	<constant>PIX_FMT_XXX</constant>, defined in the <link
330	linkend="videodev">videodev2.h</link> header file. These identifiers
331	represent <link linkend="v4l2-fourcc">four character (FourCC) codes</link>
332	which are also listed below, however they are not the same as those
333	used in the Windows world.</para>
334	
335	    <para>For some formats, data is stored in separate, discontiguous
336	memory buffers. Those formats are identified by a separate set of FourCC codes
337	and are referred to as "multi-planar formats". For example, a YUV422 frame is
338	normally stored in one memory buffer, but it can also be placed in two or three
339	separate buffers, with Y component in one buffer and CbCr components in another
340	in the 2-planar version or with each component in its own buffer in the
341	3-planar case. Those sub-buffers are referred to as "planes".</para>
342	  </section>
343	
344	  <section id="colorspaces">
345	    <title>Colorspaces</title>
346	
347	    <para>'Color' is a very complex concept and depends on physics, chemistry and
348	biology. Just because you have three numbers that describe the 'red', 'green'
349	and 'blue' components of the color of a pixel does not mean that you can accurately
350	display that color. A colorspace defines what it actually <emphasis>means</emphasis>
351	to have an RGB value of e.g. (255,&nbsp;0,&nbsp;0). That is, which color should be
352	reproduced on the screen in a perfectly calibrated environment.</para>
353	
354	    <para>In order to do that we first need to have a good definition of
355	color, i.e. some way to uniquely and unambiguously define a color so that someone
356	else can reproduce it. Human color vision is trichromatic since the human eye has
357	color receptors that are sensitive to three different wavelengths of light. Hence
358	the need to use three numbers to describe color. Be glad you are not a mantis shrimp
359	as those are sensitive to 12 different wavelengths, so instead of RGB we would be
360	using the ABCDEFGHIJKL colorspace...</para>
361	
362	    <para>Color exists only in the eye and brain and is the result of how strongly
363	color receptors are stimulated. This is based on the Spectral
364	Power Distribution (SPD) which is a graph showing the intensity (radiant power)
365	of the light at wavelengths covering the visible spectrum as it enters the eye.
366	The science of colorimetry is about the relationship between the SPD and color as
367	perceived by the human brain.</para>
368	
369	    <para>Since the human eye has only three color receptors it is perfectly
370	possible that different SPDs will result in the same stimulation of those receptors
371	and are perceived as the same color, even though the SPD of the light is
372	different.</para>
373	
374	   <para>In the 1920s experiments were devised to determine the relationship
375	between SPDs and the perceived color and that resulted in the CIE 1931 standard
376	that defines spectral weighting functions that model the perception of color.
377	Specifically that standard defines functions that can take an SPD and calculate
378	the stimulus for each color receptor. After some further mathematical transforms
379	these stimuli are known as the <emphasis>CIE XYZ tristimulus</emphasis> values
380	and these X, Y and Z values describe a color as perceived by a human unambiguously.
381	These X, Y and Z values are all in the range [0&hellip;1].</para>
382	
383	   <para>The Y value in the CIE XYZ colorspace corresponds to luminance. Often
384	the CIE XYZ colorspace is transformed to the normalized CIE xyY colorspace:</para>
385	
386	   <para>x = X / (X + Y + Z)</para>
387	   <para>y = Y / (X + Y + Z)</para>
388	
389	   <para>The x and y values are the chromaticity coordinates and can be used to
390	define a color without the luminance component Y. It is very confusing to
391	have such similar names for these colorspaces. Just be aware that if colors
392	are specified with lower case 'x' and 'y', then the CIE xyY colorspace is
393	used. Upper case 'X' and 'Y' refer to the CIE XYZ colorspace. Also, y has nothing
394	to do with luminance. Together x and y specify a color, and Y the luminance.
395	That is really all you need to remember from a practical point of view. At
396	the end of this section you will find reading resources that go into much more
397	detail if you are interested.
398	</para>
399	
400	   <para>A monitor or TV will reproduce colors by emitting light at three
401	different wavelengths, the combination of which will stimulate the color receptors
402	in the eye and thus cause the perception of color. Historically these wavelengths
403	were defined by the red, green and blue phosphors used in the displays. These
404	<emphasis>color primaries</emphasis> are part of what defines a colorspace.</para>
405	
406	    <para>Different display devices will have different primaries and some
407	primaries are more suitable for some display technologies than others. This has
408	resulted in a variety of colorspaces that are used for different display
409	technologies or uses. To define a colorspace you need to define the three
410	color primaries (these are typically defined as x,&nbsp;y chromaticity coordinates
411	from the CIE xyY colorspace) but also the white reference: that is the color obtained
412	when all three primaries are at maximum power. This determines the relative power
413	or energy of the primaries. This is usually chosen to be close to daylight which has
414	been defined as the CIE D65 Illuminant.</para>
415	
416	    <para>To recapitulate: the CIE XYZ colorspace uniquely identifies colors.
417	Other colorspaces are defined by three chromaticity coordinates defined in the
418	CIE xyY colorspace. Based on those a 3x3 matrix can be constructed that
419	transforms CIE XYZ colors to colors in the new colorspace.
420	</para>
421	
422	    <para>Both the CIE XYZ and the RGB colorspace that are derived from the
423	specific chromaticity primaries are linear colorspaces. But neither the eye,
424	nor display technology is linear. Doubling the values of all components in
425	the linear colorspace will not be perceived as twice the intensity of the color.
426	So each colorspace also defines a transfer function that takes a linear color
427	component value and transforms it to the non-linear component value, which is a
428	closer match to the non-linear performance of both the eye and displays. Linear
429	component values are denoted RGB, non-linear are denoted as R'G'B'. In general
430	colors used in graphics are all R'G'B', except in openGL which uses linear RGB.
431	Special care should be taken when dealing with openGL to provide linear RGB colors
432	or to use the built-in openGL support to apply the inverse transfer function.</para>
433	
434	    <para>The final piece that defines a colorspace is a function that
435	transforms non-linear R'G'B' to non-linear Y'CbCr. This function is determined
436	by the so-called luma coefficients. There may be multiple possible Y'CbCr
437	encodings allowed for the same colorspace. Many encodings of color
438	prefer to use luma (Y') and chroma (CbCr) instead of R'G'B'. Since the human
439	eye is more sensitive to differences in luminance than in color this encoding
440	allows one to reduce the amount of color information compared to the luma
441	data. Note that the luma (Y') is unrelated to the Y in the CIE XYZ colorspace.
442	Also note that Y'CbCr is often called YCbCr or YUV even though these are
443	strictly speaking wrong.</para>
444	
445	    <para>Sometimes people confuse Y'CbCr as being a colorspace. This is not
446	correct, it is just an encoding of an R'G'B' color into luma and chroma
447	values. The underlying colorspace that is associated with the R'G'B' color
448	is also associated with the Y'CbCr color.</para>
449	
450	    <para>The final step is how the RGB, R'G'B' or Y'CbCr values are
451	quantized. The CIE XYZ colorspace where X, Y and Z are in the range
452	[0&hellip;1] describes all colors that humans can perceive, but the transform to
453	another colorspace will produce colors that are outside the [0&hellip;1] range.
454	Once clamped to the [0&hellip;1] range those colors can no longer be reproduced
455	in that colorspace. This clamping is what reduces the extent or gamut of the
456	colorspace. How the range of [0&hellip;1] is translated to integer values in the
457	range of [0&hellip;255] (or higher, depending on the color depth) is called the
458	quantization. This is <emphasis>not</emphasis> part of the colorspace
459	definition. In practice RGB or R'G'B' values are full range, i.e. they
460	use the full [0&hellip;255] range. Y'CbCr values on the other hand are limited
461	range with Y' using [16&hellip;235] and Cb and Cr using [16&hellip;240].</para>
462	
463	    <para>Unfortunately, in some cases limited range RGB is also used
464	where the components use the range [16&hellip;235]. And full range Y'CbCr also exists
465	using the [0&hellip;255] range.</para>
466	
467	    <para>In order to correctly interpret a color you need to know the
468	quantization range, whether it is R'G'B' or Y'CbCr, the used Y'CbCr encoding
469	and the colorspace.
470	From that information you can calculate the corresponding CIE XYZ color
471	and map that again to whatever colorspace your display device uses.</para>
472	
473	    <para>The colorspace definition itself consists of the three
474	chromaticity primaries, the white reference chromaticity, a transfer
475	function and the luma coefficients needed to transform R'G'B' to Y'CbCr. While
476	some colorspace standards correctly define all four, quite often the colorspace
477	standard only defines some, and you have to rely on other standards for
478	the missing pieces. The fact that colorspaces are often a mix of different
479	standards also led to very confusing naming conventions where the name of
480	a standard was used to name a colorspace when in fact that standard was
481	part of various other colorspaces as well.</para>
482	
483	    <para>If you want to read more about colors and colorspaces, then the
484	following resources are useful: <xref linkend="poynton" /> is a good practical
485	book for video engineers, <xref linkend="colimg" /> has a much broader scope and
486	describes many more aspects of color (physics, chemistry, biology, etc.).
487	The <ulink url="http://www.brucelindbloom.com">http://www.brucelindbloom.com</ulink>
488	website is an excellent resource, especially with respect to the mathematics behind
489	colorspace conversions. The wikipedia <ulink url="http://en.wikipedia.org/wiki/CIE_1931_color_space#CIE_xy_chromaticity_diagram_and_the_CIE_xyY_color_space">CIE 1931 colorspace</ulink> article
490	is also very useful.</para>
491	  </section>
492	
493	  <section>
494	    <title>Defining Colorspaces in V4L2</title>
495	    <para>In V4L2 colorspaces are defined by four values. The first is the colorspace
496	identifier (&v4l2-colorspace;) which defines the chromaticities, the default transfer
497	function, the default Y'CbCr encoding and the default quantization method. The second
498	is the transfer function identifier (&v4l2-xfer-func;) to specify non-standard
499	transfer functions. The third is the Y'CbCr encoding identifier (&v4l2-ycbcr-encoding;)
500	to specify non-standard Y'CbCr encodings and the fourth is the quantization identifier
501	(&v4l2-quantization;) to specify non-standard quantization methods. Most of the time
502	only the colorspace field of &v4l2-pix-format; or &v4l2-pix-format-mplane; needs to
503	be filled in. Note that the default R'G'B' quantization is full range for all
504	colorspaces except for BT.2020 which uses limited range R'G'B' quantization.</para>
505	
506	    <table pgwide="1" frame="none" id="v4l2-colorspace">
507	      <title>V4L2 Colorspaces</title>
508	      <tgroup cols="2" align="left">
509		&cs-def;
510		<thead>
511		  <row>
512		    <entry>Identifier</entry>
513		    <entry>Details</entry>
514		  </row>
515		</thead>
516		<tbody valign="top">
517		  <row>
518		    <entry><constant>V4L2_COLORSPACE_DEFAULT</constant></entry>
519		    <entry>The default colorspace. This can be used by applications to let the
520		    driver fill in the colorspace.</entry>
521		  </row>
522		  <row>
523		    <entry><constant>V4L2_COLORSPACE_SMPTE170M</constant></entry>
524		    <entry>See <xref linkend="col-smpte-170m" />.</entry>
525		  </row>
526		  <row>
527		    <entry><constant>V4L2_COLORSPACE_REC709</constant></entry>
528		    <entry>See <xref linkend="col-rec709" />.</entry>
529		  </row>
530		  <row>
531		    <entry><constant>V4L2_COLORSPACE_SRGB</constant></entry>
532		    <entry>See <xref linkend="col-srgb" />.</entry>
533		  </row>
534		  <row>
535		    <entry><constant>V4L2_COLORSPACE_ADOBERGB</constant></entry>
536		    <entry>See <xref linkend="col-adobergb" />.</entry>
537		  </row>
538		  <row>
539		    <entry><constant>V4L2_COLORSPACE_BT2020</constant></entry>
540		    <entry>See <xref linkend="col-bt2020" />.</entry>
541		  </row>
542		  <row>
543		    <entry><constant>V4L2_COLORSPACE_DCI_P3</constant></entry>
544		    <entry>See <xref linkend="col-dcip3" />.</entry>
545		  </row>
546		  <row>
547		    <entry><constant>V4L2_COLORSPACE_SMPTE240M</constant></entry>
548		    <entry>See <xref linkend="col-smpte-240m" />.</entry>
549		  </row>
550		  <row>
551		    <entry><constant>V4L2_COLORSPACE_470_SYSTEM_M</constant></entry>
552		    <entry>See <xref linkend="col-sysm" />.</entry>
553		  </row>
554		  <row>
555		    <entry><constant>V4L2_COLORSPACE_470_SYSTEM_BG</constant></entry>
556		    <entry>See <xref linkend="col-sysbg" />.</entry>
557		  </row>
558		  <row>
559		    <entry><constant>V4L2_COLORSPACE_JPEG</constant></entry>
560		    <entry>See <xref linkend="col-jpeg" />.</entry>
561		  </row>
562		  <row>
563		    <entry><constant>V4L2_COLORSPACE_RAW</constant></entry>
564		    <entry>The raw colorspace. This is used for raw image capture where
565		    the image is minimally processed and is using the internal colorspace
566		    of the device. The software that processes an image using this
567		    'colorspace' will have to know the internals of the capture device.</entry>
568		  </row>
569		</tbody>
570	      </tgroup>
571	    </table>
572	
573	    <table pgwide="1" frame="none" id="v4l2-xfer-func">
574	      <title>V4L2 Transfer Function</title>
575	      <tgroup cols="2" align="left">
576		&cs-def;
577		<thead>
578		  <row>
579		    <entry>Identifier</entry>
580		    <entry>Details</entry>
581		  </row>
582		</thead>
583		<tbody valign="top">
584		  <row>
585		    <entry><constant>V4L2_XFER_FUNC_DEFAULT</constant></entry>
586		    <entry>Use the default transfer function as defined by the colorspace.</entry>
587		  </row>
588		  <row>
589		    <entry><constant>V4L2_XFER_FUNC_709</constant></entry>
590		    <entry>Use the Rec. 709 transfer function.</entry>
591		  </row>
592		  <row>
593		    <entry><constant>V4L2_XFER_FUNC_SRGB</constant></entry>
594		    <entry>Use the sRGB transfer function.</entry>
595		  </row>
596		  <row>
597		    <entry><constant>V4L2_XFER_FUNC_ADOBERGB</constant></entry>
598		    <entry>Use the AdobeRGB transfer function.</entry>
599		  </row>
600		  <row>
601		    <entry><constant>V4L2_XFER_FUNC_SMPTE240M</constant></entry>
602		    <entry>Use the SMPTE 240M transfer function.</entry>
603		  </row>
604		  <row>
605		    <entry><constant>V4L2_XFER_FUNC_NONE</constant></entry>
606		    <entry>Do not use a transfer function (i.e. use linear RGB values).</entry>
607		  </row>
608		  <row>
609		    <entry><constant>V4L2_XFER_FUNC_DCI_P3</constant></entry>
610		    <entry>Use the DCI-P3 transfer function.</entry>
611		  </row>
612		  <row>
613		    <entry><constant>V4L2_XFER_FUNC_SMPTE2084</constant></entry>
614		    <entry>Use the SMPTE 2084 transfer function.</entry>
615		  </row>
616		</tbody>
617	      </tgroup>
618	    </table>
619	
620	    <table pgwide="1" frame="none" id="v4l2-ycbcr-encoding">
621	      <title>V4L2 Y'CbCr Encodings</title>
622	      <tgroup cols="2" align="left">
623		&cs-def;
624		<thead>
625		  <row>
626		    <entry>Identifier</entry>
627		    <entry>Details</entry>
628		  </row>
629		</thead>
630		<tbody valign="top">
631		  <row>
632		    <entry><constant>V4L2_YCBCR_ENC_DEFAULT</constant></entry>
633		    <entry>Use the default Y'CbCr encoding as defined by the colorspace.</entry>
634		  </row>
635		  <row>
636		    <entry><constant>V4L2_YCBCR_ENC_601</constant></entry>
637		    <entry>Use the BT.601 Y'CbCr encoding.</entry>
638		  </row>
639		  <row>
640		    <entry><constant>V4L2_YCBCR_ENC_709</constant></entry>
641		    <entry>Use the Rec. 709 Y'CbCr encoding.</entry>
642		  </row>
643		  <row>
644		    <entry><constant>V4L2_YCBCR_ENC_XV601</constant></entry>
645		    <entry>Use the extended gamut xvYCC BT.601 encoding.</entry>
646		  </row>
647		  <row>
648		    <entry><constant>V4L2_YCBCR_ENC_XV709</constant></entry>
649		    <entry>Use the extended gamut xvYCC Rec. 709 encoding.</entry>
650		  </row>
651		  <row>
652		    <entry><constant>V4L2_YCBCR_ENC_SYCC</constant></entry>
653		    <entry>Use the extended gamut sYCC encoding.</entry>
654		  </row>
655		  <row>
656		    <entry><constant>V4L2_YCBCR_ENC_BT2020</constant></entry>
657		    <entry>Use the default non-constant luminance BT.2020 Y'CbCr encoding.</entry>
658		  </row>
659		  <row>
660		    <entry><constant>V4L2_YCBCR_ENC_BT2020_CONST_LUM</constant></entry>
661		    <entry>Use the constant luminance BT.2020 Yc'CbcCrc encoding.</entry>
662		  </row>
663		</tbody>
664	      </tgroup>
665	    </table>
666	
667	    <table pgwide="1" frame="none" id="v4l2-quantization">
668	      <title>V4L2 Quantization Methods</title>
669	      <tgroup cols="2" align="left">
670		&cs-def;
671		<thead>
672		  <row>
673		    <entry>Identifier</entry>
674		    <entry>Details</entry>
675		  </row>
676		</thead>
677		<tbody valign="top">
678		  <row>
679		    <entry><constant>V4L2_QUANTIZATION_DEFAULT</constant></entry>
680		    <entry>Use the default quantization encoding as defined by the colorspace.
681	This is always full range for R'G'B' (except for the BT.2020 colorspace) and usually
682	limited range for Y'CbCr.</entry>
683		  </row>
684		  <row>
685		    <entry><constant>V4L2_QUANTIZATION_FULL_RANGE</constant></entry>
686		    <entry>Use the full range quantization encoding. I.e. the range [0&hellip;1]
687	is mapped to [0&hellip;255] (with possible clipping to [1&hellip;254] to avoid the
688	0x00 and 0xff values). Cb and Cr are mapped from [-0.5&hellip;0.5] to [0&hellip;255]
689	(with possible clipping to [1&hellip;254] to avoid the 0x00 and 0xff values).</entry>
690		  </row>
691		  <row>
692		    <entry><constant>V4L2_QUANTIZATION_LIM_RANGE</constant></entry>
693		    <entry>Use the limited range quantization encoding. I.e. the range [0&hellip;1]
694	is mapped to [16&hellip;235]. Cb and Cr are mapped from [-0.5&hellip;0.5] to [16&hellip;240].
695	</entry>
696		  </row>
697		</tbody>
698	      </tgroup>
699	    </table>
700	  </section>
701	
702	  <section>
703	    <title>Detailed Colorspace Descriptions</title>
704	    <section id="col-smpte-170m">
705	      <title>Colorspace SMPTE 170M (<constant>V4L2_COLORSPACE_SMPTE170M</constant>)</title>
706	      <para>The <xref linkend="smpte170m" /> standard defines the colorspace used by NTSC and PAL and by SDTV
707	in general. The default transfer function is <constant>V4L2_XFER_FUNC_709</constant>.
708	The default Y'CbCr encoding is <constant>V4L2_YCBCR_ENC_601</constant>.
709	The default Y'CbCr quantization is limited range. The chromaticities of the primary colors and
710	the white reference are:</para>
711	      <table frame="none">
712	        <title>SMPTE 170M Chromaticities</title>
713	        <tgroup cols="3" align="left">
714	          &cs-str;
715	    	<thead>
716	    	  <row>
717	    	    <entry>Color</entry>
718	    	    <entry>x</entry>
719	    	    <entry>y</entry>
720	    	  </row>
721	    	</thead>
722	          <tbody valign="top">
723	            <row>
724	              <entry>Red</entry>
725	              <entry>0.630</entry>
726	              <entry>0.340</entry>
727	            </row>
728	            <row>
729	              <entry>Green</entry>
730	              <entry>0.310</entry>
731	              <entry>0.595</entry>
732	            </row>
733	            <row>
734	              <entry>Blue</entry>
735	              <entry>0.155</entry>
736	              <entry>0.070</entry>
737	            </row>
738	            <row>
739	              <entry>White Reference (D65)</entry>
740	              <entry>0.3127</entry>
741	              <entry>0.3290</entry>
742	            </row>
743	          </tbody>
744	        </tgroup>
745	      </table>
746	      <para>The red, green and blue chromaticities are also often referred to
747	as the SMPTE C set, so this colorspace is sometimes called SMPTE C as well.</para>
748	      <variablelist>
749		<varlistentry>
750	          <term>The transfer function defined for SMPTE 170M is the same as the
751	one defined in Rec. 709.</term>
752		  <listitem>
753	            <para>L' = -1.099(-L)<superscript>0.45</superscript>&nbsp;+&nbsp;0.099&nbsp;for&nbsp;L&nbsp;&le;&nbsp;-0.018</para>
754	            <para>L' = 4.5L&nbsp;for&nbsp;-0.018&nbsp;&lt;&nbsp;L&nbsp;&lt;&nbsp;0.018</para>
755	            <para>L' = 1.099L<superscript>0.45</superscript>&nbsp;-&nbsp;0.099&nbsp;for&nbsp;L&nbsp;&ge;&nbsp;0.018</para>
756		  </listitem>
757		</varlistentry>
758	      </variablelist>
759	      <variablelist>
760		<varlistentry>
761	          <term>Inverse Transfer function:</term>
762		  <listitem>
763	            <para>L = -((L'&nbsp;-&nbsp;0.099)&nbsp;/&nbsp;-1.099)<superscript>1/0.45</superscript>&nbsp;for&nbsp;L'&nbsp;&le;&nbsp;-0.081</para>
764	            <para>L = L'&nbsp;/&nbsp;4.5&nbsp;for&nbsp;-0.081&nbsp;&lt;&nbsp;L'&nbsp;&lt;&nbsp;0.081</para>
765	            <para>L = ((L'&nbsp;+&nbsp;0.099)&nbsp;/&nbsp;1.099)<superscript>1/0.45</superscript>&nbsp;for&nbsp;L'&nbsp;&ge;&nbsp;0.081</para>
766		  </listitem>
767		</varlistentry>
768	      </variablelist>
769	      <variablelist>
770		<varlistentry>
771	      	  <term>The luminance (Y') and color difference (Cb and Cr) are obtained with
772	the following <constant>V4L2_YCBCR_ENC_601</constant> encoding:</term>
773		  <listitem>
774	            <para>Y'&nbsp;=&nbsp;0.299R'&nbsp;+&nbsp;0.587G'&nbsp;+&nbsp;0.114B'</para>
775	            <para>Cb&nbsp;=&nbsp;-0.169R'&nbsp;-&nbsp;0.331G'&nbsp;+&nbsp;0.5B'</para>
776	            <para>Cr&nbsp;=&nbsp;0.5R'&nbsp;-&nbsp;0.419G'&nbsp;-&nbsp;0.081B'</para>
777		  </listitem>
778		</varlistentry>
779	      </variablelist>
780	      <para>Y' is clamped to the range [0&hellip;1] and Cb and Cr are
781	clamped to the range [-0.5&hellip;0.5]. This conversion to Y'CbCr is identical to the one
782	defined in the <xref linkend="itu601" /> standard and this colorspace is sometimes called BT.601 as well, even
783	though BT.601 does not mention any color primaries.</para>
784	      <para>The default quantization is limited range, but full range is possible although
785	rarely seen.</para>
786	    </section>
787	
788	    <section id="col-rec709">
789	      <title>Colorspace Rec. 709 (<constant>V4L2_COLORSPACE_REC709</constant>)</title>
790	      <para>The <xref linkend="itu709" /> standard defines the colorspace used by HDTV in general.
791	The default transfer function is <constant>V4L2_XFER_FUNC_709</constant>. The default
792	Y'CbCr encoding is <constant>V4L2_YCBCR_ENC_709</constant>. The default Y'CbCr quantization is
793	limited range. The chromaticities of the primary colors and the white reference are:</para>
794	      <table frame="none">
795	        <title>Rec. 709 Chromaticities</title>
796	        <tgroup cols="3" align="left">
797	          &cs-str;
798	    	<thead>
799	    	  <row>
800	    	    <entry>Color</entry>
801	    	    <entry>x</entry>
802	    	    <entry>y</entry>
803	    	  </row>
804	    	</thead>
805	          <tbody valign="top">
806	            <row>
807	              <entry>Red</entry>
808	              <entry>0.640</entry>
809	              <entry>0.330</entry>
810	            </row>
811	            <row>
812	              <entry>Green</entry>
813	              <entry>0.300</entry>
814	              <entry>0.600</entry>
815	            </row>
816	            <row>
817	              <entry>Blue</entry>
818	              <entry>0.150</entry>
819	              <entry>0.060</entry>
820	            </row>
821	            <row>
822	              <entry>White Reference (D65)</entry>
823	              <entry>0.3127</entry>
824	              <entry>0.3290</entry>
825	            </row>
826	          </tbody>
827	        </tgroup>
828	      </table>
829	      <para>The full name of this standard is Rec. ITU-R BT.709-5.</para>
830	      <variablelist>
831		<varlistentry>
832	          <term>Transfer function. Normally L is in the range [0&hellip;1], but for the extended
833	gamut xvYCC encoding values outside that range are allowed.</term>
834		  <listitem>
835	            <para>L' = -1.099(-L)<superscript>0.45</superscript>&nbsp;+&nbsp;0.099&nbsp;for&nbsp;L&nbsp;&le;&nbsp;-0.018</para>
836	            <para>L' = 4.5L&nbsp;for&nbsp;-0.018&nbsp;&lt;&nbsp;L&nbsp;&lt;&nbsp;0.018</para>
837	            <para>L' = 1.099L<superscript>0.45</superscript>&nbsp;-&nbsp;0.099&nbsp;for&nbsp;L&nbsp;&ge;&nbsp;0.018</para>
838		  </listitem>
839		</varlistentry>
840	      </variablelist>
841	      <variablelist>
842		<varlistentry>
843	          <term>Inverse Transfer function:</term>
844		  <listitem>
845	            <para>L = -((L'&nbsp;-&nbsp;0.099)&nbsp;/&nbsp;-1.099)<superscript>1/0.45</superscript>&nbsp;for&nbsp;L'&nbsp;&le;&nbsp;-0.081</para>
846	            <para>L = L'&nbsp;/&nbsp;4.5&nbsp;for&nbsp;-0.081&nbsp;&lt;&nbsp;L'&nbsp;&lt;&nbsp;0.081</para>
847	            <para>L = ((L'&nbsp;+&nbsp;0.099)&nbsp;/&nbsp;1.099)<superscript>1/0.45</superscript>&nbsp;for&nbsp;L'&nbsp;&ge;&nbsp;0.081</para>
848		  </listitem>
849		</varlistentry>
850	      </variablelist>
851	      <variablelist>
852		<varlistentry>
853	      	  <term>The luminance (Y') and color difference (Cb and Cr) are obtained with the following
854	<constant>V4L2_YCBCR_ENC_709</constant> encoding:</term>
855		  <listitem>
856	            <para>Y'&nbsp;=&nbsp;0.2126R'&nbsp;+&nbsp;0.7152G'&nbsp;+&nbsp;0.0722B'</para>
857	            <para>Cb&nbsp;=&nbsp;-0.1146R'&nbsp;-&nbsp;0.3854G'&nbsp;+&nbsp;0.5B'</para>
858	            <para>Cr&nbsp;=&nbsp;0.5R'&nbsp;-&nbsp;0.4542G'&nbsp;-&nbsp;0.0458B'</para>
859		  </listitem>
860		</varlistentry>
861	      </variablelist>
862	      <para>Y' is clamped to the range [0&hellip;1] and Cb and Cr are
863	clamped to the range [-0.5&hellip;0.5].</para>
864	      <para>The default quantization is limited range, but full range is possible although
865	rarely seen.</para>
866	      <para>The <constant>V4L2_YCBCR_ENC_709</constant> encoding described above is the default
867	for this colorspace, but it can be overridden with <constant>V4L2_YCBCR_ENC_601</constant>, in which
868	case the BT.601 Y'CbCr encoding is used.</para>
869	      <para>Two additional extended gamut Y'CbCr encodings are also possible with this colorspace:</para>
870	      <variablelist>
871		<varlistentry>
872	      	  <term>The xvYCC 709 encoding (<constant>V4L2_YCBCR_ENC_XV709</constant>, <xref linkend="xvycc" />)
873	is similar to the Rec. 709 encoding, but it allows for R', G' and B' values that are outside the range
874	[0&hellip;1]. The resulting Y', Cb and Cr values are scaled and offset:</term>
875		  <listitem>
876	            <para>Y'&nbsp;=&nbsp;(219&nbsp;/&nbsp;256)&nbsp;*&nbsp;(0.2126R'&nbsp;+&nbsp;0.7152G'&nbsp;+&nbsp;0.0722B')&nbsp;+&nbsp;(16&nbsp;/&nbsp;256)</para>
877	            <para>Cb&nbsp;=&nbsp;(224&nbsp;/&nbsp;256)&nbsp;*&nbsp;(-0.1146R'&nbsp;-&nbsp;0.3854G'&nbsp;+&nbsp;0.5B')</para>
878	            <para>Cr&nbsp;=&nbsp;(224&nbsp;/&nbsp;256)&nbsp;*&nbsp;(0.5R'&nbsp;-&nbsp;0.4542G'&nbsp;-&nbsp;0.0458B')</para>
879		  </listitem>
880		</varlistentry>
881	      </variablelist>
882	      <variablelist>
883		<varlistentry>
884	         <term>The xvYCC 601 encoding (<constant>V4L2_YCBCR_ENC_XV601</constant>, <xref linkend="xvycc" />) is similar
885	to the BT.601 encoding, but it allows for R', G' and B' values that are outside the range
886	[0&hellip;1]. The resulting Y', Cb and Cr values are scaled and offset:</term>
887		  <listitem>
888	            <para>Y'&nbsp;=&nbsp;(219&nbsp;/&nbsp;256)&nbsp;*&nbsp;(0.299R'&nbsp;+&nbsp;0.587G'&nbsp;+&nbsp;0.114B')&nbsp;+&nbsp;(16&nbsp;/&nbsp;256)</para>
889	            <para>Cb&nbsp;=&nbsp;(224&nbsp;/&nbsp;256)&nbsp;*&nbsp;(-0.169R'&nbsp;-&nbsp;0.331G'&nbsp;+&nbsp;0.5B')</para>
890	            <para>Cr&nbsp;=&nbsp;(224&nbsp;/&nbsp;256)&nbsp;*&nbsp;(0.5R'&nbsp;-&nbsp;0.419G'&nbsp;-&nbsp;0.081B')</para>
891		  </listitem>
892		</varlistentry>
893	      </variablelist>
894	      <para>Y' is clamped to the range [0&hellip;1] and Cb and Cr are clamped
895	to the range [-0.5&hellip;0.5]. The non-standard xvYCC 709 or xvYCC 601 encodings can be used by
896	selecting <constant>V4L2_YCBCR_ENC_XV709</constant> or <constant>V4L2_YCBCR_ENC_XV601</constant>.
897	The xvYCC encodings always use full range quantization.</para>
898	    </section>
899	
900	    <section id="col-srgb">
901	      <title>Colorspace sRGB (<constant>V4L2_COLORSPACE_SRGB</constant>)</title>
902	      <para>The <xref linkend="srgb" /> standard defines the colorspace used by most webcams
903	and computer graphics. The default transfer function is <constant>V4L2_XFER_FUNC_SRGB</constant>.
904	The default Y'CbCr encoding is <constant>V4L2_YCBCR_ENC_SYCC</constant>. The default Y'CbCr
905	quantization is full range. The chromaticities of the primary colors and the white
906	reference are:</para>
907	      <table frame="none">
908	        <title>sRGB Chromaticities</title>
909	        <tgroup cols="3" align="left">
910	          &cs-str;
911	    	<thead>
912	    	  <row>
913	    	    <entry>Color</entry>
914	    	    <entry>x</entry>
915	    	    <entry>y</entry>
916	    	  </row>
917	    	</thead>
918	          <tbody valign="top">
919	            <row>
920	              <entry>Red</entry>
921	              <entry>0.640</entry>
922	              <entry>0.330</entry>
923	            </row>
924	            <row>
925	              <entry>Green</entry>
926	              <entry>0.300</entry>
927	              <entry>0.600</entry>
928	            </row>
929	            <row>
930	              <entry>Blue</entry>
931	              <entry>0.150</entry>
932	              <entry>0.060</entry>
933	            </row>
934	            <row>
935	              <entry>White Reference (D65)</entry>
936	              <entry>0.3127</entry>
937	              <entry>0.3290</entry>
938	            </row>
939	          </tbody>
940	        </tgroup>
941	      </table>
942	      <para>These chromaticities are identical to the Rec. 709 colorspace.</para>
943	      <variablelist>
944		<varlistentry>
945	          <term>Transfer function. Note that negative values for L are only used by the Y'CbCr conversion.</term>
946		  <listitem>
947	            <para>L' = -1.055(-L)<superscript>1/2.4</superscript>&nbsp;+&nbsp;0.055&nbsp;for&nbsp;L&nbsp;&lt;&nbsp;-0.0031308</para>
948	            <para>L' = 12.92L&nbsp;for&nbsp;-0.0031308&nbsp;&le;&nbsp;L&nbsp;&le;&nbsp;0.0031308</para>
949	            <para>L' = 1.055L<superscript>1/2.4</superscript>&nbsp;-&nbsp;0.055&nbsp;for&nbsp;0.0031308&nbsp;&lt;&nbsp;L&nbsp;&le;&nbsp;1</para>
950		  </listitem>
951		</varlistentry>
952		<varlistentry>
953	          <term>Inverse Transfer function:</term>
954		  <listitem>
955	            <para>L = -((-L'&nbsp;+&nbsp;0.055)&nbsp;/&nbsp;1.055)<superscript>2.4</superscript>&nbsp;for&nbsp;L'&nbsp;&lt;&nbsp;-0.04045</para>
956	            <para>L = L'&nbsp;/&nbsp;12.92&nbsp;for&nbsp;-0.04045&nbsp;&le;&nbsp;L'&nbsp;&le;&nbsp;0.04045</para>
957	            <para>L = ((L'&nbsp;+&nbsp;0.055)&nbsp;/&nbsp;1.055)<superscript>2.4</superscript>&nbsp;for&nbsp;L'&nbsp;&gt;&nbsp;0.04045</para>
958		  </listitem>
959		</varlistentry>
960	      </variablelist>
961	      <variablelist>
962		<varlistentry>
963	      	  <term>The luminance (Y') and color difference (Cb and Cr) are obtained with the following
964	<constant>V4L2_YCBCR_ENC_SYCC</constant> encoding as defined by <xref linkend="sycc" />:</term>
965		  <listitem>
966	            <para>Y'&nbsp;=&nbsp;0.2990R'&nbsp;+&nbsp;0.5870G'&nbsp;+&nbsp;0.1140B'</para>
967	            <para>Cb&nbsp;=&nbsp;-0.1687R'&nbsp;-&nbsp;0.3313G'&nbsp;+&nbsp;0.5B'</para>
968	            <para>Cr&nbsp;=&nbsp;0.5R'&nbsp;-&nbsp;0.4187G'&nbsp;-&nbsp;0.0813B'</para>
969		  </listitem>
970		</varlistentry>
971	      </variablelist>
972	      <para>Y' is clamped to the range [0&hellip;1] and Cb and Cr are clamped
973	to the range [-0.5&hellip;0.5]. The <constant>V4L2_YCBCR_ENC_SYCC</constant> quantization is always
974	full range. Although this Y'CbCr encoding looks very similar to the <constant>V4L2_YCBCR_ENC_XV601</constant>
975	encoding, it is not. The <constant>V4L2_YCBCR_ENC_XV601</constant> scales and offsets the Y'CbCr
976	values before quantization, but this encoding does not do that.</para>
977	    </section>
978	
979	    <section id="col-adobergb">
980	      <title>Colorspace Adobe RGB (<constant>V4L2_COLORSPACE_ADOBERGB</constant>)</title>
981	      <para>The <xref linkend="adobergb" /> standard defines the colorspace used by computer graphics
982	that use the AdobeRGB colorspace. This is also known as the <xref linkend="oprgb" /> standard.
983	The default transfer function is <constant>V4L2_XFER_FUNC_ADOBERGB</constant>.
984	The default Y'CbCr encoding is <constant>V4L2_YCBCR_ENC_601</constant>. The default Y'CbCr
985	quantization is limited range. The chromaticities of the primary colors and the white reference
986	are:</para>
987	      <table frame="none">
988	        <title>Adobe RGB Chromaticities</title>
989	        <tgroup cols="3" align="left">
990	          &cs-str;
991	    	<thead>
992	    	  <row>
993	    	    <entry>Color</entry>
994	    	    <entry>x</entry>
995	    	    <entry>y</entry>
996	    	  </row>
997	    	</thead>
998	          <tbody valign="top">
999	            <row>
1000	              <entry>Red</entry>
1001	              <entry>0.6400</entry>
1002	              <entry>0.3300</entry>
1003	            </row>
1004	            <row>
1005	              <entry>Green</entry>
1006	              <entry>0.2100</entry>
1007	              <entry>0.7100</entry>
1008	            </row>
1009	            <row>
1010	              <entry>Blue</entry>
1011	              <entry>0.1500</entry>
1012	              <entry>0.0600</entry>
1013	            </row>
1014	            <row>
1015	              <entry>White Reference (D65)</entry>
1016	              <entry>0.3127</entry>
1017	              <entry>0.3290</entry>
1018	            </row>
1019	          </tbody>
1020	        </tgroup>
1021	      </table>
1022	      <variablelist>
1023		<varlistentry>
1024	          <term>Transfer function:</term>
1025		  <listitem>
1026	            <para>L' = L<superscript>1/2.19921875</superscript></para>
1027		  </listitem>
1028		</varlistentry>
1029		<varlistentry>
1030	          <term>Inverse Transfer function:</term>
1031		  <listitem>
1032	            <para>L = L'<superscript>2.19921875</superscript></para>
1033		  </listitem>
1034		</varlistentry>
1035	      </variablelist>
1036	      <variablelist>
1037		<varlistentry>
1038	      	  <term>The luminance (Y') and color difference (Cb and Cr) are obtained with the
1039	following <constant>V4L2_YCBCR_ENC_601</constant> encoding:</term>
1040		  <listitem>
1041	            <para>Y'&nbsp;=&nbsp;0.299R'&nbsp;+&nbsp;0.587G'&nbsp;+&nbsp;0.114B'</para>
1042	            <para>Cb&nbsp;=&nbsp;-0.169R'&nbsp;-&nbsp;0.331G'&nbsp;+&nbsp;0.5B'</para>
1043	            <para>Cr&nbsp;=&nbsp;0.5R'&nbsp;-&nbsp;0.419G'&nbsp;-&nbsp;0.081B'</para>
1044		  </listitem>
1045		</varlistentry>
1046	      </variablelist>
1047	      <para>Y' is clamped to the range [0&hellip;1] and Cb and Cr are
1048	clamped to the range [-0.5&hellip;0.5]. This transform is identical to one defined in
1049	SMPTE 170M/BT.601. The Y'CbCr quantization is limited range.</para>
1050	    </section>
1051	
1052	    <section id="col-bt2020">
1053	      <title>Colorspace BT.2020 (<constant>V4L2_COLORSPACE_BT2020</constant>)</title>
1054	      <para>The <xref linkend="itu2020" /> standard defines the colorspace used by Ultra-high definition
1055	television (UHDTV). The default transfer function is <constant>V4L2_XFER_FUNC_709</constant>.
1056	The default Y'CbCr encoding is <constant>V4L2_YCBCR_ENC_BT2020</constant>.
1057	The default R'G'B' quantization is limited range (!), and so is the default Y'CbCr quantization.
1058	The chromaticities of the primary colors and the white reference are:</para>
1059	      <table frame="none">
1060	        <title>BT.2020 Chromaticities</title>
1061	        <tgroup cols="3" align="left">
1062	          &cs-str;
1063	    	<thead>
1064	    	  <row>
1065	    	    <entry>Color</entry>
1066	    	    <entry>x</entry>
1067	    	    <entry>y</entry>
1068	    	  </row>
1069	    	</thead>
1070	          <tbody valign="top">
1071	            <row>
1072	              <entry>Red</entry>
1073	              <entry>0.708</entry>
1074	              <entry>0.292</entry>
1075	            </row>
1076	            <row>
1077	              <entry>Green</entry>
1078	              <entry>0.170</entry>
1079	              <entry>0.797</entry>
1080	            </row>
1081	            <row>
1082	              <entry>Blue</entry>
1083	              <entry>0.131</entry>
1084	              <entry>0.046</entry>
1085	            </row>
1086	            <row>
1087	              <entry>White Reference (D65)</entry>
1088	              <entry>0.3127</entry>
1089	              <entry>0.3290</entry>
1090	            </row>
1091	          </tbody>
1092	        </tgroup>
1093	      </table>
1094	      <variablelist>
1095		<varlistentry>
1096	          <term>Transfer function (same as Rec. 709):</term>
1097		  <listitem>
1098	            <para>L' = 4.5L&nbsp;for&nbsp;0&nbsp;&le;&nbsp;L&nbsp;&lt;&nbsp;0.018</para>
1099	            <para>L' = 1.099L<superscript>0.45</superscript>&nbsp;-&nbsp;0.099&nbsp;for&nbsp;0.018&nbsp;&le;&nbsp;L&nbsp;&le;&nbsp;1</para>
1100		  </listitem>
1101		</varlistentry>
1102		<varlistentry>
1103	          <term>Inverse Transfer function:</term>
1104		  <listitem>
1105	            <para>L = L'&nbsp;/&nbsp;4.5&nbsp;for&nbsp;L'&nbsp;&lt;&nbsp;0.081</para>
1106	            <para>L = ((L'&nbsp;+&nbsp;0.099)&nbsp;/&nbsp;1.099)<superscript>1/0.45</superscript>&nbsp;for&nbsp;L'&nbsp;&ge;&nbsp;0.081</para>
1107		  </listitem>
1108		</varlistentry>
1109	      </variablelist>
1110	      <variablelist>
1111		<varlistentry>
1112	      	  <term>The luminance (Y') and color difference (Cb and Cr) are obtained with the
1113	following <constant>V4L2_YCBCR_ENC_BT2020</constant> encoding:</term>
1114		  <listitem>
1115	            <para>Y'&nbsp;=&nbsp;0.2627R'&nbsp;+&nbsp;0.6780G'&nbsp;+&nbsp;0.0593B'</para>
1116	            <para>Cb&nbsp;=&nbsp;-0.1396R'&nbsp;-&nbsp;0.3604G'&nbsp;+&nbsp;0.5B'</para>
1117	            <para>Cr&nbsp;=&nbsp;0.5R'&nbsp;-&nbsp;0.4598G'&nbsp;-&nbsp;0.0402B'</para>
1118		  </listitem>
1119		</varlistentry>
1120	      </variablelist>
1121	      <para>Y' is clamped to the range [0&hellip;1] and Cb and Cr are
1122	clamped to the range [-0.5&hellip;0.5]. The Y'CbCr quantization is limited range.</para>
1123	      <para>There is also an alternate constant luminance R'G'B' to Yc'CbcCrc
1124	(<constant>V4L2_YCBCR_ENC_BT2020_CONST_LUM</constant>) encoding:</para>
1125	      <variablelist>
1126		<varlistentry>
1127	      	  <term>Luma:</term>
1128		  <listitem>
1129	            <para>Yc'&nbsp;=&nbsp;(0.2627R&nbsp;+&nbsp;0.6780G&nbsp;+&nbsp;0.0593B)'</para>
1130		  </listitem>
1131		</varlistentry>
1132	      </variablelist>
1133	      <variablelist>
1134		<varlistentry>
1135	      	  <term>B'&nbsp;-&nbsp;Yc'&nbsp;&le;&nbsp;0:</term>
1136		  <listitem>
1137	            <para>Cbc&nbsp;=&nbsp;(B'&nbsp;-&nbsp;Yc')&nbsp;/&nbsp;1.9404</para>
1138		  </listitem>
1139		</varlistentry>
1140	      </variablelist>
1141	      <variablelist>
1142		<varlistentry>
1143	      	  <term>B'&nbsp;-&nbsp;Yc'&nbsp;&gt;&nbsp;0:</term>
1144		  <listitem>
1145	            <para>Cbc&nbsp;=&nbsp;(B'&nbsp;-&nbsp;Yc')&nbsp;/&nbsp;1.5816</para>
1146		  </listitem>
1147		</varlistentry>
1148	      </variablelist>
1149	      <variablelist>
1150		<varlistentry>
1151	      	  <term>R'&nbsp;-&nbsp;Yc'&nbsp;&le;&nbsp;0:</term>
1152		  <listitem>
1153	            <para>Crc&nbsp;=&nbsp;(R'&nbsp;-&nbsp;Y')&nbsp;/&nbsp;1.7184</para>
1154		  </listitem>
1155		</varlistentry>
1156	      </variablelist>
1157	      <variablelist>
1158		<varlistentry>
1159	      	  <term>R'&nbsp;-&nbsp;Yc'&nbsp;&gt;&nbsp;0:</term>
1160		  <listitem>
1161	            <para>Crc&nbsp;=&nbsp;(R'&nbsp;-&nbsp;Y')&nbsp;/&nbsp;0.9936</para>
1162		  </listitem>
1163		</varlistentry>
1164	      </variablelist>
1165	      <para>Yc' is clamped to the range [0&hellip;1] and Cbc and Crc are
1166	clamped to the range [-0.5&hellip;0.5]. The Yc'CbcCrc quantization is limited range.</para>
1167	    </section>
1168	
1169	    <section id="col-dcip3">
1170	      <title>Colorspace DCI-P3 (<constant>V4L2_COLORSPACE_DCI_P3</constant>)</title>
1171	      <para>The <xref linkend="smpte431" /> standard defines the colorspace used by cinema
1172	projectors that use the DCI-P3 colorspace.
1173	The default transfer function is <constant>V4L2_XFER_FUNC_DCI_P3</constant>.
1174	The default Y'CbCr encoding is <constant>V4L2_YCBCR_ENC_709</constant>. Note that this
1175	colorspace does not specify a Y'CbCr encoding since it is not meant to be encoded
1176	to Y'CbCr. So this default Y'CbCr encoding was picked because it is the HDTV
1177	encoding. The default Y'CbCr quantization is limited range. The chromaticities of
1178	the primary colors and the white reference are:</para>
1179	      <table frame="none">
1180	        <title>DCI-P3 Chromaticities</title>
1181	        <tgroup cols="3" align="left">
1182	          &cs-str;
1183	    	<thead>
1184	    	  <row>
1185	    	    <entry>Color</entry>
1186	    	    <entry>x</entry>
1187	    	    <entry>y</entry>
1188	    	  </row>
1189	    	</thead>
1190	          <tbody valign="top">
1191	            <row>
1192	              <entry>Red</entry>
1193	              <entry>0.6800</entry>
1194	              <entry>0.3200</entry>
1195	            </row>
1196	            <row>
1197	              <entry>Green</entry>
1198	              <entry>0.2650</entry>
1199	              <entry>0.6900</entry>
1200	            </row>
1201	            <row>
1202	              <entry>Blue</entry>
1203	              <entry>0.1500</entry>
1204	              <entry>0.0600</entry>
1205	            </row>
1206	            <row>
1207	              <entry>White Reference</entry>
1208	              <entry>0.3140</entry>
1209	              <entry>0.3510</entry>
1210	            </row>
1211	          </tbody>
1212	        </tgroup>
1213	      </table>
1214	      <variablelist>
1215		<varlistentry>
1216	          <term>Transfer function:</term>
1217		  <listitem>
1218	            <para>L' = L<superscript>1/2.6</superscript></para>
1219		  </listitem>
1220		</varlistentry>
1221		<varlistentry>
1222	          <term>Inverse Transfer function:</term>
1223		  <listitem>
1224	            <para>L = L'<superscript>2.6</superscript></para>
1225		  </listitem>
1226		</varlistentry>
1227	      </variablelist>
1228	      <para>Y'CbCr encoding is not specified. V4L2 defaults to Rec. 709.</para>
1229	    </section>
1230	
1231	    <section id="col-smpte-240m">
1232	      <title>Colorspace SMPTE 240M (<constant>V4L2_COLORSPACE_SMPTE240M</constant>)</title>
1233	      <para>The <xref linkend="smpte240m" /> standard was an interim standard used during
1234	the early days of HDTV (1988-1998).  It has been superseded by Rec. 709.
1235	The default transfer function is <constant>V4L2_XFER_FUNC_SMPTE240M</constant>.
1236	The default Y'CbCr encoding is <constant>V4L2_YCBCR_ENC_SMPTE240M</constant>.
1237	The default Y'CbCr quantization is limited range. The chromaticities of the primary colors and the
1238	white reference are:</para>
1239	      <table frame="none">
1240	        <title>SMPTE 240M Chromaticities</title>
1241	        <tgroup cols="3" align="left">
1242	          &cs-str;
1243	    	<thead>
1244	    	  <row>
1245	    	    <entry>Color</entry>
1246	    	    <entry>x</entry>
1247	    	    <entry>y</entry>
1248	    	  </row>
1249	    	</thead>
1250	          <tbody valign="top">
1251	            <row>
1252	              <entry>Red</entry>
1253	              <entry>0.630</entry>
1254	              <entry>0.340</entry>
1255	            </row>
1256	            <row>
1257	              <entry>Green</entry>
1258	              <entry>0.310</entry>
1259	              <entry>0.595</entry>
1260	            </row>
1261	            <row>
1262	              <entry>Blue</entry>
1263	              <entry>0.155</entry>
1264	              <entry>0.070</entry>
1265	            </row>
1266	            <row>
1267	              <entry>White Reference (D65)</entry>
1268	              <entry>0.3127</entry>
1269	              <entry>0.3290</entry>
1270	            </row>
1271	          </tbody>
1272	        </tgroup>
1273	      </table>
1274	      <para>These chromaticities are identical to the SMPTE 170M colorspace.</para>
1275	      <variablelist>
1276		<varlistentry>
1277	          <term>Transfer function:</term>
1278		  <listitem>
1279	            <para>L' = 4L&nbsp;for&nbsp;0&nbsp;&le;&nbsp;L&nbsp;&lt;&nbsp;0.0228</para>
1280	            <para>L' = 1.1115L<superscript>0.45</superscript>&nbsp;-&nbsp;0.1115&nbsp;for&nbsp;0.0228&nbsp;&le;&nbsp;L&nbsp;&le;&nbsp;1</para>
1281		  </listitem>
1282		</varlistentry>
1283		<varlistentry>
1284	          <term>Inverse Transfer function:</term>
1285		  <listitem>
1286	            <para>L = L'&nbsp;/&nbsp;4&nbsp;for&nbsp;0&nbsp;&le;&nbsp;L'&nbsp;&lt;&nbsp;0.0913</para>
1287	            <para>L = ((L'&nbsp;+&nbsp;0.1115)&nbsp;/&nbsp;1.1115)<superscript>1/0.45</superscript>&nbsp;for&nbsp;L'&nbsp;&ge;&nbsp;0.0913</para>
1288		  </listitem>
1289		</varlistentry>
1290	      </variablelist>
1291	      <variablelist>
1292		<varlistentry>
1293	      	  <term>The luminance (Y') and color difference (Cb and Cr) are obtained with the
1294	following <constant>V4L2_YCBCR_ENC_SMPTE240M</constant> encoding:</term>
1295		  <listitem>
1296	            <para>Y'&nbsp;=&nbsp;0.2122R'&nbsp;+&nbsp;0.7013G'&nbsp;+&nbsp;0.0865B'</para>
1297	            <para>Cb&nbsp;=&nbsp;-0.1161R'&nbsp;-&nbsp;0.3839G'&nbsp;+&nbsp;0.5B'</para>
1298	            <para>Cr&nbsp;=&nbsp;0.5R'&nbsp;-&nbsp;0.4451G'&nbsp;-&nbsp;0.0549B'</para>
1299		  </listitem>
1300		</varlistentry>
1301	      </variablelist>
1302	      <para>Yc' is clamped to the range [0&hellip;1] and Cbc and Crc are
1303	clamped to the range [-0.5&hellip;0.5]. The Y'CbCr quantization is limited range.</para>
1304	    </section>
1305	
1306	    <section id="col-sysm">
1307	      <title>Colorspace NTSC 1953 (<constant>V4L2_COLORSPACE_470_SYSTEM_M</constant>)</title>
1308	      <para>This standard defines the colorspace used by NTSC in 1953. In practice this
1309	colorspace is obsolete and SMPTE 170M should be used instead.
1310	The default transfer function is <constant>V4L2_XFER_FUNC_709</constant>.
1311	The default Y'CbCr encoding is <constant>V4L2_YCBCR_ENC_601</constant>.
1312	The default Y'CbCr quantization is limited range.
1313	The chromaticities of the primary colors and the white reference are:</para>
1314	      <table frame="none">
1315	        <title>NTSC 1953 Chromaticities</title>
1316	        <tgroup cols="3" align="left">
1317	          &cs-str;
1318	    	<thead>
1319	    	  <row>
1320	    	    <entry>Color</entry>
1321	    	    <entry>x</entry>
1322	    	    <entry>y</entry>
1323	    	  </row>
1324	    	</thead>
1325	          <tbody valign="top">
1326	            <row>
1327	              <entry>Red</entry>
1328	              <entry>0.67</entry>
1329	              <entry>0.33</entry>
1330	            </row>
1331	            <row>
1332	              <entry>Green</entry>
1333	              <entry>0.21</entry>
1334	              <entry>0.71</entry>
1335	            </row>
1336	            <row>
1337	              <entry>Blue</entry>
1338	              <entry>0.14</entry>
1339	              <entry>0.08</entry>
1340	            </row>
1341	            <row>
1342	              <entry>White Reference (C)</entry>
1343	              <entry>0.310</entry>
1344	              <entry>0.316</entry>
1345	            </row>
1346	          </tbody>
1347	        </tgroup>
1348	      </table>
1349	      <para>Note that this colorspace uses Illuminant C instead of D65 as the
1350	white reference. To correctly convert an image in this colorspace to another
1351	that uses D65 you need to apply a chromatic adaptation algorithm such as the
1352	Bradford method.</para>
1353	      <variablelist>
1354		<varlistentry>
1355	          <term>The transfer function was never properly defined for NTSC 1953. The
1356	Rec. 709 transfer function is recommended in the literature:</term>
1357		  <listitem>
1358	            <para>L' = 4.5L&nbsp;for&nbsp;0&nbsp;&le;&nbsp;L&nbsp;&lt;&nbsp;0.018</para>
1359	            <para>L' = 1.099L<superscript>0.45</superscript>&nbsp;-&nbsp;0.099&nbsp;for&nbsp;0.018&nbsp;&le;&nbsp;L&nbsp;&le;&nbsp;1</para>
1360		  </listitem>
1361		</varlistentry>
1362		<varlistentry>
1363	          <term>Inverse Transfer function:</term>
1364		  <listitem>
1365	            <para>L = L'&nbsp;/&nbsp;4.5&nbsp;for&nbsp;L'&nbsp;&lt;&nbsp;0.081</para>
1366	            <para>L = ((L'&nbsp;+&nbsp;0.099)&nbsp;/&nbsp;1.099)<superscript>1/0.45</superscript>&nbsp;for&nbsp;L'&nbsp;&ge;&nbsp;0.081</para>
1367		  </listitem>
1368		</varlistentry>
1369	      </variablelist>
1370	      <variablelist>
1371		<varlistentry>
1372	      	  <term>The luminance (Y') and color difference (Cb and Cr) are obtained with the
1373	following <constant>V4L2_YCBCR_ENC_601</constant> encoding:</term>
1374		  <listitem>
1375	            <para>Y'&nbsp;=&nbsp;0.299R'&nbsp;+&nbsp;0.587G'&nbsp;+&nbsp;0.114B'</para>
1376	            <para>Cb&nbsp;=&nbsp;-0.169R'&nbsp;-&nbsp;0.331G'&nbsp;+&nbsp;0.5B'</para>
1377	            <para>Cr&nbsp;=&nbsp;0.5R'&nbsp;-&nbsp;0.419G'&nbsp;-&nbsp;0.081B'</para>
1378		  </listitem>
1379		</varlistentry>
1380	      </variablelist>
1381	      <para>Y' is clamped to the range [0&hellip;1] and Cb and Cr are
1382	clamped to the range [-0.5&hellip;0.5]. The Y'CbCr quantization is limited range.
1383	This transform is identical to one defined in SMPTE 170M/BT.601.</para>
1384	    </section>
1385	
1386	    <section id="col-sysbg">
1387	      <title>Colorspace EBU Tech. 3213 (<constant>V4L2_COLORSPACE_470_SYSTEM_BG</constant>)</title>
1388	      <para>The <xref linkend="tech3213" /> standard defines the colorspace used by PAL/SECAM in 1975. In practice this
1389	colorspace is obsolete and SMPTE 170M should be used instead.
1390	The default transfer function is <constant>V4L2_XFER_FUNC_709</constant>.
1391	The default Y'CbCr encoding is <constant>V4L2_YCBCR_ENC_601</constant>.
1392	The default Y'CbCr quantization is limited range.
1393	The chromaticities of the primary colors and the white reference are:</para>
1394	      <table frame="none">
1395	        <title>EBU Tech. 3213 Chromaticities</title>
1396	        <tgroup cols="3" align="left">
1397	          &cs-str;
1398	    	<thead>
1399	    	  <row>
1400	    	    <entry>Color</entry>
1401	    	    <entry>x</entry>
1402	    	    <entry>y</entry>
1403	    	  </row>
1404	    	</thead>
1405	          <tbody valign="top">
1406	            <row>
1407	              <entry>Red</entry>
1408	              <entry>0.64</entry>
1409	              <entry>0.33</entry>
1410	            </row>
1411	            <row>
1412	              <entry>Green</entry>
1413	              <entry>0.29</entry>
1414	              <entry>0.60</entry>
1415	            </row>
1416	            <row>
1417	              <entry>Blue</entry>
1418	              <entry>0.15</entry>
1419	              <entry>0.06</entry>
1420	            </row>
1421	            <row>
1422	              <entry>White Reference (D65)</entry>
1423	              <entry>0.3127</entry>
1424	              <entry>0.3290</entry>
1425	            </row>
1426	          </tbody>
1427	        </tgroup>
1428	      </table>
1429	      <variablelist>
1430		<varlistentry>
1431	          <term>The transfer function was never properly defined for this colorspace.
1432	The Rec. 709 transfer function is recommended in the literature:</term>
1433		  <listitem>
1434	            <para>L' = 4.5L&nbsp;for&nbsp;0&nbsp;&le;&nbsp;L&nbsp;&lt;&nbsp;0.018</para>
1435	            <para>L' = 1.099L<superscript>0.45</superscript>&nbsp;-&nbsp;0.099&nbsp;for&nbsp;0.018&nbsp;&le;&nbsp;L&nbsp;&le;&nbsp;1</para>
1436		  </listitem>
1437		</varlistentry>
1438		<varlistentry>
1439	          <term>Inverse Transfer function:</term>
1440		  <listitem>
1441	            <para>L = L'&nbsp;/&nbsp;4.5&nbsp;for&nbsp;L'&nbsp;&lt;&nbsp;0.081</para>
1442	            <para>L = ((L'&nbsp;+&nbsp;0.099)&nbsp;/&nbsp;1.099)<superscript>1/0.45</superscript>&nbsp;for&nbsp;L'&nbsp;&ge;&nbsp;0.081</para>
1443		  </listitem>
1444		</varlistentry>
1445	      </variablelist>
1446	      <variablelist>
1447		<varlistentry>
1448	      	  <term>The luminance (Y') and color difference (Cb and Cr) are obtained with the
1449	following <constant>V4L2_YCBCR_ENC_601</constant> encoding:</term>
1450		  <listitem>
1451	            <para>Y'&nbsp;=&nbsp;0.299R'&nbsp;+&nbsp;0.587G'&nbsp;+&nbsp;0.114B'</para>
1452	            <para>Cb&nbsp;=&nbsp;-0.169R'&nbsp;-&nbsp;0.331G'&nbsp;+&nbsp;0.5B'</para>
1453	            <para>Cr&nbsp;=&nbsp;0.5R'&nbsp;-&nbsp;0.419G'&nbsp;-&nbsp;0.081B'</para>
1454		  </listitem>
1455		</varlistentry>
1456	      </variablelist>
1457	      <para>Y' is clamped to the range [0&hellip;1] and Cb and Cr are
1458	clamped to the range [-0.5&hellip;0.5]. The Y'CbCr quantization is limited range.
1459	This transform is identical to one defined in SMPTE 170M/BT.601.</para>
1460	    </section>
1461	
1462	    <section id="col-jpeg">
1463	      <title>Colorspace JPEG (<constant>V4L2_COLORSPACE_JPEG</constant>)</title>
1464	      <para>This colorspace defines the colorspace used by most (Motion-)JPEG formats. The chromaticities
1465	of the primary colors and the white reference are identical to sRGB. The transfer
1466	function use is <constant>V4L2_XFER_FUNC_SRGB</constant>. The Y'CbCr encoding is
1467	<constant>V4L2_YCBCR_ENC_601</constant> with full range quantization where
1468	Y' is scaled to [0&hellip;255] and Cb/Cr are scaled to [-128&hellip;128] and
1469	then clipped to [-128&hellip;127].</para>
1470	      <para>Note that the JPEG standard does not actually store colorspace information.
1471	So if something other than sRGB is used, then the driver will have to set that information
1472	explicitly. Effectively <constant>V4L2_COLORSPACE_JPEG</constant> can be considered to be
1473	an abbreviation for <constant>V4L2_COLORSPACE_SRGB</constant>, <constant>V4L2_YCBCR_ENC_601</constant>
1474	and <constant>V4L2_QUANTIZATION_FULL_RANGE</constant>.</para>
1475	    </section>
1476	
1477	  </section>
1478	
1479	  <section>
1480	    <title>Detailed Transfer Function Descriptions</title>
1481	    <section id="xf-smpte-2084">
1482	      <title>Transfer Function SMPTE 2084 (<constant>V4L2_XFER_FUNC_SMPTE2084</constant>)</title>
1483	      <para>The <xref linkend="smpte2084" /> standard defines the transfer function used by
1484	High Dynamic Range content.</para>
1485	      <variablelist>
1486		<varlistentry>
1487	          <term>Constants:</term>
1488		  <listitem>
1489	            <para>m1 = (2610 / 4096) / 4</para>
1490	            <para>m2 = (2523 / 4096) * 128</para>
1491	            <para>c1 = 3424 / 4096</para>
1492	            <para>c2 = (2413 / 4096) * 32</para>
1493	            <para>c3 = (2392 / 4096) * 32</para>
1494		  </listitem>
1495		</varlistentry>
1496		<varlistentry>
1497	          <term>Transfer function:</term>
1498		  <listitem>
1499	            <para>L' = ((c1 + c2 * L<superscript>m1</superscript>) / (1 + c3 * L<superscript>m1</superscript>))<superscript>m2</superscript></para>
1500		  </listitem>
1501		</varlistentry>
1502	      </variablelist>
1503	      <variablelist>
1504		<varlistentry>
1505	          <term>Inverse Transfer function:</term>
1506		  <listitem>
1507	            <para>L = (max(L'<superscript>1/m2</superscript> - c1, 0) / (c2 - c3 * L'<superscript>1/m2</superscript>))<superscript>1/m1</superscript></para>
1508		  </listitem>
1509		</varlistentry>
1510	      </variablelist>
1511	    </section>
1512	  </section>
1513	
1514	  <section id="pixfmt-indexed">
1515	    <title>Indexed Format</title>
1516	
1517	    <para>In this format each pixel is represented by an 8 bit index
1518	into a 256 entry ARGB palette. It is intended for <link
1519	linkend="osd">Video Output Overlays</link> only. There are no ioctls to
1520	access the palette, this must be done with ioctls of the Linux framebuffer API.</para>
1521	
1522	    <table pgwide="0" frame="none">
1523	      <title>Indexed Image Format</title>
1524	      <tgroup cols="37" align="center">
1525		<colspec colname="id" align="left" />
1526		<colspec colname="fourcc" />
1527		<colspec colname="bit" />
1528	
1529		<colspec colnum="4" colname="b07" align="center" />
1530		<colspec colnum="5" colname="b06" align="center" />
1531		<colspec colnum="6" colname="b05" align="center" />
1532		<colspec colnum="7" colname="b04" align="center" />
1533		<colspec colnum="8" colname="b03" align="center" />
1534		<colspec colnum="9" colname="b02" align="center" />
1535		<colspec colnum="10" colname="b01" align="center" />
1536		<colspec colnum="11" colname="b00" align="center" />
1537	
1538		<spanspec namest="b07" nameend="b00" spanname="b0" />
1539		<spanspec namest="b17" nameend="b10" spanname="b1" />
1540		<spanspec namest="b27" nameend="b20" spanname="b2" />
1541		<spanspec namest="b37" nameend="b30" spanname="b3" />
1542		<thead>
1543		  <row>
1544		    <entry>Identifier</entry>
1545		    <entry>Code</entry>
1546		    <entry>&nbsp;</entry>
1547		    <entry spanname="b0">Byte&nbsp;0</entry>
1548		  </row>
1549		  <row>
1550		    <entry>&nbsp;</entry>
1551		    <entry>&nbsp;</entry>
1552		    <entry>Bit</entry>
1553		    <entry>7</entry>
1554		    <entry>6</entry>
1555		    <entry>5</entry>
1556		    <entry>4</entry>
1557		    <entry>3</entry>
1558		    <entry>2</entry>
1559		    <entry>1</entry>
1560		    <entry>0</entry>
1561		  </row>
1562		</thead>
1563		<tbody valign="top">
1564		  <row id="V4L2-PIX-FMT-PAL8">
1565		    <entry><constant>V4L2_PIX_FMT_PAL8</constant></entry>
1566		    <entry>'PAL8'</entry>
1567		    <entry></entry>
1568		    <entry>i<subscript>7</subscript></entry>
1569		    <entry>i<subscript>6</subscript></entry>
1570		    <entry>i<subscript>5</subscript></entry>
1571		    <entry>i<subscript>4</subscript></entry>
1572		    <entry>i<subscript>3</subscript></entry>
1573		    <entry>i<subscript>2</subscript></entry>
1574		    <entry>i<subscript>1</subscript></entry>
1575		    <entry>i<subscript>0</subscript></entry>
1576		  </row>
1577		</tbody>
1578	      </tgroup>
1579	    </table>
1580	  </section>
1581	
1582	  <section id="pixfmt-rgb">
1583	    <title>RGB Formats</title>
1584	
1585	    &sub-packed-rgb;
1586	    &sub-sbggr8;
1587	    &sub-sgbrg8;
1588	    &sub-sgrbg8;
1589	    &sub-srggb8;
1590	    &sub-sbggr16;
1591	    &sub-srggb10;
1592	    &sub-srggb10p;
1593	    &sub-srggb10alaw8;
1594	    &sub-srggb10dpcm8;
1595	    &sub-srggb12;
1596	  </section>
1597	
1598	  <section id="yuv-formats">
1599	    <title>YUV Formats</title>
1600	
1601	    <para>YUV is the format native to TV broadcast and composite video
1602	signals. It separates the brightness information (Y) from the color
1603	information (U and V or Cb and Cr). The color information consists of
1604	red and blue <emphasis>color difference</emphasis> signals, this way
1605	the green component can be reconstructed by subtracting from the
1606	brightness component. See <xref linkend="colorspaces" /> for conversion
1607	examples. YUV was chosen because early television would only transmit
1608	brightness information. To add color in a way compatible with existing
1609	receivers a new signal carrier was added to transmit the color
1610	difference signals. Secondary in the YUV format the U and V components
1611	usually have lower resolution than the Y component. This is an analog
1612	video compression technique taking advantage of a property of the
1613	human visual system, being more sensitive to brightness
1614	information.</para>
1615	
1616	    &sub-packed-yuv;
1617	    &sub-grey;
1618	    &sub-y10;
1619	    &sub-y12;
1620	    &sub-y10b;
1621	    &sub-y16;
1622	    &sub-y16-be;
1623	    &sub-y8i;
1624	    &sub-y12i;
1625	    &sub-uv8;
1626	    &sub-yuyv;
1627	    &sub-uyvy;
1628	    &sub-yvyu;
1629	    &sub-vyuy;
1630	    &sub-y41p;
1631	    &sub-yuv420;
1632	    &sub-yuv420m;
1633	    &sub-yuv422m;
1634	    &sub-yuv444m;
1635	    &sub-yuv410;
1636	    &sub-yuv422p;
1637	    &sub-yuv411p;
1638	    &sub-nv12;
1639	    &sub-nv12m;
1640	    &sub-nv12mt;
1641	    &sub-nv16;
1642	    &sub-nv16m;
1643	    &sub-nv24;
1644	    &sub-m420;
1645	  </section>
1646	
1647	  <section id="depth-formats">
1648	    <title>Depth Formats</title>
1649	    <para>Depth data provides distance to points, mapped onto the image plane
1650	    </para>
1651	
1652	    &sub-z16;
1653	  </section>
1654	
1655	  <section>
1656	    <title>Compressed Formats</title>
1657	
1658	    <table pgwide="1" frame="none" id="compressed-formats">
1659	      <title>Compressed Image Formats</title>
1660	      <tgroup cols="3" align="left">
1661		&cs-def;
1662		<thead>
1663		  <row>
1664		    <entry>Identifier</entry>
1665		    <entry>Code</entry>
1666		    <entry>Details</entry>
1667		  </row>
1668		</thead>
1669		<tbody valign="top">
1670		 <row id="V4L2-PIX-FMT-JPEG">
1671		    <entry><constant>V4L2_PIX_FMT_JPEG</constant></entry>
1672		    <entry>'JPEG'</entry>
1673		    <entry>TBD. See also &VIDIOC-G-JPEGCOMP;,
1674		    &VIDIOC-S-JPEGCOMP;.</entry>
1675		  </row>
1676		  <row id="V4L2-PIX-FMT-MPEG">
1677		    <entry><constant>V4L2_PIX_FMT_MPEG</constant></entry>
1678		    <entry>'MPEG'</entry>
1679		    <entry>MPEG multiplexed stream. The actual format is determined by
1680	extended control <constant>V4L2_CID_MPEG_STREAM_TYPE</constant>, see
1681	<xref linkend="mpeg-control-id" />.</entry>
1682		  </row>
1683		  <row id="V4L2-PIX-FMT-H264">
1684			<entry><constant>V4L2_PIX_FMT_H264</constant></entry>
1685			<entry>'H264'</entry>
1686			<entry>H264 video elementary stream with start codes.</entry>
1687		  </row>
1688		  <row id="V4L2-PIX-FMT-H264-NO-SC">
1689			<entry><constant>V4L2_PIX_FMT_H264_NO_SC</constant></entry>
1690			<entry>'AVC1'</entry>
1691			<entry>H264 video elementary stream without start codes.</entry>
1692		  </row>
1693		  <row id="V4L2-PIX-FMT-H264-MVC">
1694			<entry><constant>V4L2_PIX_FMT_H264_MVC</constant></entry>
1695			<entry>'M264'</entry>
1696			<entry>H264 MVC video elementary stream.</entry>
1697		  </row>
1698		  <row id="V4L2-PIX-FMT-H263">
1699			<entry><constant>V4L2_PIX_FMT_H263</constant></entry>
1700			<entry>'H263'</entry>
1701			<entry>H263 video elementary stream.</entry>
1702		  </row>
1703		  <row id="V4L2-PIX-FMT-MPEG1">
1704			<entry><constant>V4L2_PIX_FMT_MPEG1</constant></entry>
1705			<entry>'MPG1'</entry>
1706			<entry>MPEG1 video elementary stream.</entry>
1707		  </row>
1708		  <row id="V4L2-PIX-FMT-MPEG2">
1709			<entry><constant>V4L2_PIX_FMT_MPEG2</constant></entry>
1710			<entry>'MPG2'</entry>
1711			<entry>MPEG2 video elementary stream.</entry>
1712		  </row>
1713		  <row id="V4L2-PIX-FMT-MPEG4">
1714			<entry><constant>V4L2_PIX_FMT_MPEG4</constant></entry>
1715			<entry>'MPG4'</entry>
1716			<entry>MPEG4 video elementary stream.</entry>
1717		  </row>
1718		  <row id="V4L2-PIX-FMT-XVID">
1719			<entry><constant>V4L2_PIX_FMT_XVID</constant></entry>
1720			<entry>'XVID'</entry>
1721			<entry>Xvid video elementary stream.</entry>
1722		  </row>
1723		  <row id="V4L2-PIX-FMT-VC1-ANNEX-G">
1724			<entry><constant>V4L2_PIX_FMT_VC1_ANNEX_G</constant></entry>
1725			<entry>'VC1G'</entry>
1726			<entry>VC1, SMPTE 421M Annex G compliant stream.</entry>
1727		  </row>
1728		  <row id="V4L2-PIX-FMT-VC1-ANNEX-L">
1729			<entry><constant>V4L2_PIX_FMT_VC1_ANNEX_L</constant></entry>
1730			<entry>'VC1L'</entry>
1731			<entry>VC1, SMPTE 421M Annex L compliant stream.</entry>
1732		  </row>
1733		  <row id="V4L2-PIX-FMT-VP8">
1734			<entry><constant>V4L2_PIX_FMT_VP8</constant></entry>
1735			<entry>'VP80'</entry>
1736			<entry>VP8 video elementary stream.</entry>
1737		  </row>
1738		</tbody>
1739	      </tgroup>
1740	    </table>
1741	  </section>
1742	
1743	  <section id="sdr-formats">
1744	    <title>SDR Formats</title>
1745	
1746	    <para>These formats are used for <link linkend="sdr">SDR</link>
1747	interface only.</para>
1748	
1749	    &sub-sdr-cu08;
1750	    &sub-sdr-cu16le;
1751	    &sub-sdr-cs08;
1752	    &sub-sdr-cs14le;
1753	    &sub-sdr-ru12le;
1754	
1755	  </section>
1756	
1757	  <section id="pixfmt-reserved">
1758	    <title>Reserved Format Identifiers</title>
1759	
1760	    <para>These formats are not defined by this specification, they
1761	are just listed for reference and to avoid naming conflicts. If you
1762	want to register your own format, send an e-mail to the linux-media mailing
1763	list &v4l-ml; for inclusion in the <filename>videodev2.h</filename>
1764	file. If you want to share your format with other developers add a
1765	link to your documentation and send a copy to the linux-media mailing list
1766	for inclusion in this section. If you think your format should be listed
1767	in a standard format section please make a proposal on the linux-media mailing
1768	list.</para>
1769	
1770	    <table pgwide="1" frame="none" id="reserved-formats">
1771	      <title>Reserved Image Formats</title>
1772	      <tgroup cols="3" align="left">
1773		&cs-def;
1774		<thead>
1775		  <row>
1776		    <entry>Identifier</entry>
1777		    <entry>Code</entry>
1778		    <entry>Details</entry>
1779		  </row>
1780		</thead>
1781		<tbody valign="top">
1782		  <row id="V4L2-PIX-FMT-DV">
1783		    <entry><constant>V4L2_PIX_FMT_DV</constant></entry>
1784		    <entry>'dvsd'</entry>
1785		    <entry>unknown</entry>
1786		  </row>
1787		  <row id="V4L2-PIX-FMT-ET61X251">
1788		    <entry><constant>V4L2_PIX_FMT_ET61X251</constant></entry>
1789		    <entry>'E625'</entry>
1790		    <entry>Compressed format of the ET61X251 driver.</entry>
1791		  </row>
1792		  <row id="V4L2-PIX-FMT-HI240">
1793		    <entry><constant>V4L2_PIX_FMT_HI240</constant></entry>
1794		    <entry>'HI24'</entry>
1795		    <entry><para>8 bit RGB format used by the BTTV driver.</para></entry>
1796		  </row>
1797		  <row id="V4L2-PIX-FMT-HM12">
1798		    <entry><constant>V4L2_PIX_FMT_HM12</constant></entry>
1799		    <entry>'HM12'</entry>
1800		    <entry><para>YUV 4:2:0 format used by the
1801	IVTV driver, <ulink url="http://www.ivtvdriver.org/">
1802	http://www.ivtvdriver.org/</ulink></para><para>The format is documented in the
1803	kernel sources in the file <filename>Documentation/video4linux/cx2341x/README.hm12</filename>
1804	</para></entry>
1805		  </row>
1806		  <row id="V4L2-PIX-FMT-CPIA1">
1807		    <entry><constant>V4L2_PIX_FMT_CPIA1</constant></entry>
1808		    <entry>'CPIA'</entry>
1809		    <entry>YUV format used by the gspca cpia1 driver.</entry>
1810		  </row>
1811		  <row id="V4L2-PIX-FMT-JPGL">
1812		    <entry><constant>V4L2_PIX_FMT_JPGL</constant></entry>
1813		    <entry>'JPGL'</entry>
1814		    <entry>JPEG-Light format (Pegasus Lossless JPEG)
1815				used in Divio webcams NW 80x.</entry>
1816		  </row>
1817		  <row id="V4L2-PIX-FMT-SPCA501">
1818		    <entry><constant>V4L2_PIX_FMT_SPCA501</constant></entry>
1819		    <entry>'S501'</entry>
1820		    <entry>YUYV per line used by the gspca driver.</entry>
1821		  </row>
1822		  <row id="V4L2-PIX-FMT-SPCA505">
1823		    <entry><constant>V4L2_PIX_FMT_SPCA505</constant></entry>
1824		    <entry>'S505'</entry>
1825		    <entry>YYUV per line used by the gspca driver.</entry>
1826		  </row>
1827		  <row id="V4L2-PIX-FMT-SPCA508">
1828		    <entry><constant>V4L2_PIX_FMT_SPCA508</constant></entry>
1829		    <entry>'S508'</entry>
1830		    <entry>YUVY per line used by the gspca driver.</entry>
1831		  </row>
1832		  <row id="V4L2-PIX-FMT-SPCA561">
1833		    <entry><constant>V4L2_PIX_FMT_SPCA561</constant></entry>
1834		    <entry>'S561'</entry>
1835		    <entry>Compressed GBRG Bayer format used by the gspca driver.</entry>
1836		  </row>
1837		  <row id="V4L2-PIX-FMT-PAC207">
1838		    <entry><constant>V4L2_PIX_FMT_PAC207</constant></entry>
1839		    <entry>'P207'</entry>
1840		    <entry>Compressed BGGR Bayer format used by the gspca driver.</entry>
1841		  </row>
1842		  <row id="V4L2-PIX-FMT-MR97310A">
1843		    <entry><constant>V4L2_PIX_FMT_MR97310A</constant></entry>
1844		    <entry>'M310'</entry>
1845		    <entry>Compressed BGGR Bayer format used by the gspca driver.</entry>
1846		  </row>
1847		  <row id="V4L2-PIX-FMT-JL2005BCD">
1848		    <entry><constant>V4L2_PIX_FMT_JL2005BCD</constant></entry>
1849		    <entry>'JL20'</entry>
1850		    <entry>JPEG compressed RGGB Bayer format used by the gspca driver.</entry>
1851		  </row>
1852		  <row id="V4L2-PIX-FMT-OV511">
1853		    <entry><constant>V4L2_PIX_FMT_OV511</constant></entry>
1854		    <entry>'O511'</entry>
1855		    <entry>OV511 JPEG format used by the gspca driver.</entry>
1856		  </row>
1857		  <row id="V4L2-PIX-FMT-OV518">
1858		    <entry><constant>V4L2_PIX_FMT_OV518</constant></entry>
1859		    <entry>'O518'</entry>
1860		    <entry>OV518 JPEG format used by the gspca driver.</entry>
1861		  </row>
1862		  <row id="V4L2-PIX-FMT-PJPG">
1863		    <entry><constant>V4L2_PIX_FMT_PJPG</constant></entry>
1864		    <entry>'PJPG'</entry>
1865		    <entry>Pixart 73xx JPEG format used by the gspca driver.</entry>
1866		  </row>
1867		  <row id="V4L2-PIX-FMT-SE401">
1868		    <entry><constant>V4L2_PIX_FMT_SE401</constant></entry>
1869		    <entry>'S401'</entry>
1870		    <entry>Compressed RGB format used by the gspca se401 driver</entry>
1871		  </row>
1872		  <row id="V4L2-PIX-FMT-SQ905C">
1873		    <entry><constant>V4L2_PIX_FMT_SQ905C</constant></entry>
1874		    <entry>'905C'</entry>
1875		    <entry>Compressed RGGB bayer format used by the gspca driver.</entry>
1876		  </row>
1877		  <row id="V4L2-PIX-FMT-MJPEG">
1878		    <entry><constant>V4L2_PIX_FMT_MJPEG</constant></entry>
1879		    <entry>'MJPG'</entry>
1880		    <entry>Compressed format used by the Zoran driver</entry>
1881		  </row>
1882		  <row id="V4L2-PIX-FMT-PWC1">
1883		    <entry><constant>V4L2_PIX_FMT_PWC1</constant></entry>
1884		    <entry>'PWC1'</entry>
1885		    <entry>Compressed format of the PWC driver.</entry>
1886		  </row>
1887		  <row id="V4L2-PIX-FMT-PWC2">
1888		    <entry><constant>V4L2_PIX_FMT_PWC2</constant></entry>
1889		    <entry>'PWC2'</entry>
1890		    <entry>Compressed format of the PWC driver.</entry>
1891		  </row>
1892		  <row id="V4L2-PIX-FMT-SN9C10X">
1893		    <entry><constant>V4L2_PIX_FMT_SN9C10X</constant></entry>
1894		    <entry>'S910'</entry>
1895		    <entry>Compressed format of the SN9C102 driver.</entry>
1896		  </row>
1897		  <row id="V4L2-PIX-FMT-SN9C20X-I420">
1898		    <entry><constant>V4L2_PIX_FMT_SN9C20X_I420</constant></entry>
1899		    <entry>'S920'</entry>
1900		    <entry>YUV 4:2:0 format of the gspca sn9c20x driver.</entry>
1901		  </row>
1902		  <row id="V4L2-PIX-FMT-SN9C2028">
1903		    <entry><constant>V4L2_PIX_FMT_SN9C2028</constant></entry>
1904		    <entry>'SONX'</entry>
1905		    <entry>Compressed GBRG bayer format of the gspca sn9c2028 driver.</entry>
1906		  </row>
1907		  <row id="V4L2-PIX-FMT-STV0680">
1908		    <entry><constant>V4L2_PIX_FMT_STV0680</constant></entry>
1909		    <entry>'S680'</entry>
1910		    <entry>Bayer format of the gspca stv0680 driver.</entry>
1911		  </row>
1912		  <row id="V4L2-PIX-FMT-WNVA">
1913		    <entry><constant>V4L2_PIX_FMT_WNVA</constant></entry>
1914		    <entry>'WNVA'</entry>
1915		    <entry><para>Used by the Winnov Videum driver, <ulink
1916	url="http://www.thedirks.org/winnov/">
1917	http://www.thedirks.org/winnov/</ulink></para></entry>
1918		  </row>
1919		  <row id="V4L2-PIX-FMT-TM6000">
1920		    <entry><constant>V4L2_PIX_FMT_TM6000</constant></entry>
1921		    <entry>'TM60'</entry>
1922		    <entry><para>Used by Trident tm6000</para></entry>
1923		  </row>
1924		  <row id="V4L2-PIX-FMT-CIT-YYVYUY">
1925		    <entry><constant>V4L2_PIX_FMT_CIT_YYVYUY</constant></entry>
1926		    <entry>'CITV'</entry>
1927		    <entry><para>Used by xirlink CIT, found at IBM webcams.</para>
1928		           <para>Uses one line of Y then 1 line of VYUY</para>
1929		    </entry>
1930		  </row>
1931		  <row id="V4L2-PIX-FMT-KONICA420">
1932		    <entry><constant>V4L2_PIX_FMT_KONICA420</constant></entry>
1933		    <entry>'KONI'</entry>
1934		    <entry><para>Used by Konica webcams.</para>
1935		           <para>YUV420 planar in blocks of 256 pixels.</para>
1936		    </entry>
1937		  </row>
1938		  <row id="V4L2-PIX-FMT-YYUV">
1939		    <entry><constant>V4L2_PIX_FMT_YYUV</constant></entry>
1940		    <entry>'YYUV'</entry>
1941		    <entry>unknown</entry>
1942		  </row>
1943		  <row id="V4L2-PIX-FMT-Y4">
1944		    <entry><constant>V4L2_PIX_FMT_Y4</constant></entry>
1945		    <entry>'Y04 '</entry>
1946		    <entry>Old 4-bit greyscale format. Only the most significant 4 bits of each byte are used,
1947	the other bits are set to 0.</entry>
1948		  </row>
1949		  <row id="V4L2-PIX-FMT-Y6">
1950		    <entry><constant>V4L2_PIX_FMT_Y6</constant></entry>
1951		    <entry>'Y06 '</entry>
1952		    <entry>Old 6-bit greyscale format. Only the most significant 6 bits of each byte are used,
1953	the other bits are set to 0.</entry>
1954		  </row>
1955		  <row id="V4L2-PIX-FMT-S5C-UYVY-JPG">
1956		    <entry><constant>V4L2_PIX_FMT_S5C_UYVY_JPG</constant></entry>
1957		    <entry>'S5CI'</entry>
1958		    <entry>Two-planar format used by Samsung S5C73MX cameras. The
1959	first plane contains interleaved JPEG and UYVY image data, followed by meta data
1960	in form of an array of offsets to the UYVY data blocks. The actual pointer array
1961	follows immediately the interleaved JPEG/UYVY data, the number of entries in
1962	this array equals the height of the UYVY image. Each entry is a 4-byte unsigned
1963	integer in big endian order and it's an offset to a single pixel line of the
1964	UYVY image. The first plane can start either with JPEG or UYVY data chunk. The
1965	size of a single UYVY block equals the UYVY image's width multiplied by 2. The
1966	size of a JPEG chunk depends on the image and can vary with each line.
1967	<para>The second plane, at an offset of 4084 bytes, contains a 4-byte offset to
1968	the pointer array in the first plane. This offset is followed by a 4-byte value
1969	indicating size of the pointer array. All numbers in the second plane are also
1970	in big endian order. Remaining data in the second plane is undefined. The
1971	information in the second plane allows to easily find location of the pointer
1972	array, which can be different for each frame. The size of the pointer array is
1973	constant for given UYVY image height.</para>
1974	<para>In order to extract UYVY and JPEG frames an application can initially set
1975	a data pointer to the start of first plane and then add an offset from the first
1976	entry of the pointers table. Such a pointer indicates start of an UYVY image
1977	pixel line. Whole UYVY line can be copied to a separate buffer. These steps
1978	should be repeated for each line, i.e. the number of entries in the pointer
1979	array. Anything what's in between the UYVY lines is JPEG data and should be
1980	concatenated to form the JPEG stream. </para>
1981	</entry>
1982		  </row>
1983		</tbody>
1984	      </tgroup>
1985	    </table>
1986	
1987	    <table frame="none" pgwide="1" id="format-flags">
1988	      <title>Format Flags</title>
1989	      <tgroup cols="3">
1990		&cs-def;
1991		<tbody valign="top">
1992		  <row>
1993		    <entry><constant>V4L2_PIX_FMT_FLAG_PREMUL_ALPHA</constant></entry>
1994		    <entry>0x00000001</entry>
1995		    <entry>The color values are premultiplied by the alpha channel
1996	value. For example, if a light blue pixel with 50% transparency was described by
1997	RGBA values (128, 192, 255, 128), the same pixel described with premultiplied
1998	colors would be described by RGBA values (64, 96, 128, 128) </entry>
1999		  </row>
2000		</tbody>
2001	      </tgroup>
2002	    </table>
2003	  </section>
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