aboutsummaryrefslogtreecommitdiffstats
path: root/Documentation/media/uapi/v4l/colorspaces-details.rst
diff options
context:
space:
mode:
Diffstat (limited to 'Documentation/media/uapi/v4l/colorspaces-details.rst')
-rw-r--r--Documentation/media/uapi/v4l/colorspaces-details.rst813
1 files changed, 0 insertions, 813 deletions
diff --git a/Documentation/media/uapi/v4l/colorspaces-details.rst b/Documentation/media/uapi/v4l/colorspaces-details.rst
deleted file mode 100644
index 8b0ba3668101..000000000000
--- a/Documentation/media/uapi/v4l/colorspaces-details.rst
+++ /dev/null
@@ -1,813 +0,0 @@
-.. Permission is granted to copy, distribute and/or modify this
-.. document under the terms of the GNU Free Documentation License,
-.. Version 1.1 or any later version published by the Free Software
-.. Foundation, with no Invariant Sections, no Front-Cover Texts
-.. and no Back-Cover Texts. A copy of the license is included at
-.. Documentation/media/uapi/fdl-appendix.rst.
-..
-.. TODO: replace it to GFDL-1.1-or-later WITH no-invariant-sections
-
-********************************
-Detailed Colorspace Descriptions
-********************************
-
-
-.. _col-smpte-170m:
-
-Colorspace SMPTE 170M (V4L2_COLORSPACE_SMPTE170M)
-=================================================
-
-The :ref:`smpte170m` standard defines the colorspace used by NTSC and
-PAL and by SDTV in general. The default transfer function is
-``V4L2_XFER_FUNC_709``. The default Y'CbCr encoding is
-``V4L2_YCBCR_ENC_601``. The default Y'CbCr quantization is limited
-range. The chromaticities of the primary colors and the white reference
-are:
-
-
-
-.. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.7cm}|
-
-.. flat-table:: SMPTE 170M Chromaticities
- :header-rows: 1
- :stub-columns: 0
- :widths: 1 1 2
-
- * - Color
- - x
- - y
- * - Red
- - 0.630
- - 0.340
- * - Green
- - 0.310
- - 0.595
- * - Blue
- - 0.155
- - 0.070
- * - White Reference (D65)
- - 0.3127
- - 0.3290
-
-
-The red, green and blue chromaticities are also often referred to as the
-SMPTE C set, so this colorspace is sometimes called SMPTE C as well.
-
-The transfer function defined for SMPTE 170M is the same as the one
-defined in Rec. 709.
-
-.. math::
-
- L' = -1.099(-L)^{0.45} + 0.099 \text{, for } L \le-0.018
-
- L' = 4.5L \text{, for } -0.018 < L < 0.018
-
- L' = 1.099L^{0.45} - 0.099 \text{, for } L \ge 0.018
-
-Inverse Transfer function:
-
-.. math::
-
- L = -\left( \frac{L' - 0.099}{-1.099} \right) ^{\frac{1}{0.45}} \text{, for } L' \le -0.081
-
- L = \frac{L'}{4.5} \text{, for } -0.081 < L' < 0.081
-
- L = \left(\frac{L' + 0.099}{1.099}\right)^{\frac{1}{0.45} } \text{, for } L' \ge 0.081
-
-The luminance (Y') and color difference (Cb and Cr) are obtained with
-the following ``V4L2_YCBCR_ENC_601`` encoding:
-
-.. math::
-
- Y' = 0.2990R' + 0.5870G' + 0.1140B'
-
- Cb = -0.1687R' - 0.3313G' + 0.5B'
-
- Cr = 0.5R' - 0.4187G' - 0.0813B'
-
-Y' is clamped to the range [0…1] and Cb and Cr are clamped to the range
-[-0.5…0.5]. This conversion to Y'CbCr is identical to the one defined in
-the :ref:`itu601` standard and this colorspace is sometimes called
-BT.601 as well, even though BT.601 does not mention any color primaries.
-
-The default quantization is limited range, but full range is possible
-although rarely seen.
-
-
-.. _col-rec709:
-
-Colorspace Rec. 709 (V4L2_COLORSPACE_REC709)
-============================================
-
-The :ref:`itu709` standard defines the colorspace used by HDTV in
-general. The default transfer function is ``V4L2_XFER_FUNC_709``. The
-default Y'CbCr encoding is ``V4L2_YCBCR_ENC_709``. The default Y'CbCr
-quantization is limited range. The chromaticities of the primary colors
-and the white reference are:
-
-
-
-.. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.7cm}|
-
-.. flat-table:: Rec. 709 Chromaticities
- :header-rows: 1
- :stub-columns: 0
- :widths: 1 1 2
-
- * - Color
- - x
- - y
- * - Red
- - 0.640
- - 0.330
- * - Green
- - 0.300
- - 0.600
- * - Blue
- - 0.150
- - 0.060
- * - White Reference (D65)
- - 0.3127
- - 0.3290
-
-
-The full name of this standard is Rec. ITU-R BT.709-5.
-
-Transfer function. Normally L is in the range [0…1], but for the
-extended gamut xvYCC encoding values outside that range are allowed.
-
-.. math::
-
- L' = -1.099(-L)^{0.45} + 0.099 \text{, for } L \le -0.018
-
- L' = 4.5L \text{, for } -0.018 < L < 0.018
-
- L' = 1.099L^{0.45} - 0.099 \text{, for } L \ge 0.018
-
-Inverse Transfer function:
-
-.. math::
-
- L = -\left( \frac{L' - 0.099}{-1.099} \right)^\frac{1}{0.45} \text{, for } L' \le -0.081
-
- L = \frac{L'}{4.5}\text{, for } -0.081 < L' < 0.081
-
- L = \left(\frac{L' + 0.099}{1.099}\right)^{\frac{1}{0.45} } \text{, for } L' \ge 0.081
-
-The luminance (Y') and color difference (Cb and Cr) are obtained with
-the following ``V4L2_YCBCR_ENC_709`` encoding:
-
-.. math::
-
- Y' = 0.2126R' + 0.7152G' + 0.0722B'
-
- Cb = -0.1146R' - 0.3854G' + 0.5B'
-
- Cr = 0.5R' - 0.4542G' - 0.0458B'
-
-Y' is clamped to the range [0…1] and Cb and Cr are clamped to the range
-[-0.5…0.5].
-
-The default quantization is limited range, but full range is possible
-although rarely seen.
-
-The ``V4L2_YCBCR_ENC_709`` encoding described above is the default for
-this colorspace, but it can be overridden with ``V4L2_YCBCR_ENC_601``,
-in which case the BT.601 Y'CbCr encoding is used.
-
-Two additional extended gamut Y'CbCr encodings are also possible with
-this colorspace:
-
-The xvYCC 709 encoding (``V4L2_YCBCR_ENC_XV709``, :ref:`xvycc`) is
-similar to the Rec. 709 encoding, but it allows for R', G' and B' values
-that are outside the range [0…1]. The resulting Y', Cb and Cr values are
-scaled and offset according to the limited range formula:
-
-.. math::
-
- Y' = \frac{219}{256} * (0.2126R' + 0.7152G' + 0.0722B') + \frac{16}{256}
-
- Cb = \frac{224}{256} * (-0.1146R' - 0.3854G' + 0.5B')
-
- Cr = \frac{224}{256} * (0.5R' - 0.4542G' - 0.0458B')
-
-The xvYCC 601 encoding (``V4L2_YCBCR_ENC_XV601``, :ref:`xvycc`) is
-similar to the BT.601 encoding, but it allows for R', G' and B' values
-that are outside the range [0…1]. The resulting Y', Cb and Cr values are
-scaled and offset according to the limited range formula:
-
-.. math::
-
- Y' = \frac{219}{256} * (0.2990R' + 0.5870G' + 0.1140B') + \frac{16}{256}
-
- Cb = \frac{224}{256} * (-0.1687R' - 0.3313G' + 0.5B')
-
- Cr = \frac{224}{256} * (0.5R' - 0.4187G' - 0.0813B')
-
-Y' is clamped to the range [0…1] and Cb and Cr are clamped to the range
-[-0.5…0.5] and quantized without further scaling or offsets.
-The non-standard xvYCC 709 or xvYCC 601 encodings can be
-used by selecting ``V4L2_YCBCR_ENC_XV709`` or ``V4L2_YCBCR_ENC_XV601``.
-As seen by the xvYCC formulas these encodings always use limited range quantization,
-there is no full range variant. The whole point of these extended gamut encodings
-is that values outside the limited range are still valid, although they
-map to R', G' and B' values outside the [0…1] range and are therefore outside
-the Rec. 709 colorspace gamut.
-
-
-.. _col-srgb:
-
-Colorspace sRGB (V4L2_COLORSPACE_SRGB)
-======================================
-
-The :ref:`srgb` standard defines the colorspace used by most webcams
-and computer graphics. The default transfer function is
-``V4L2_XFER_FUNC_SRGB``. The default Y'CbCr encoding is
-``V4L2_YCBCR_ENC_601``. The default Y'CbCr quantization is limited range.
-
-Note that the :ref:`sycc` standard specifies full range quantization,
-however all current capture hardware supported by the kernel convert
-R'G'B' to limited range Y'CbCr. So choosing full range as the default
-would break how applications interpret the quantization range.
-
-The chromaticities of the primary colors and the white reference are:
-
-
-
-.. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.7cm}|
-
-.. flat-table:: sRGB Chromaticities
- :header-rows: 1
- :stub-columns: 0
- :widths: 1 1 2
-
- * - Color
- - x
- - y
- * - Red
- - 0.640
- - 0.330
- * - Green
- - 0.300
- - 0.600
- * - Blue
- - 0.150
- - 0.060
- * - White Reference (D65)
- - 0.3127
- - 0.3290
-
-
-These chromaticities are identical to the Rec. 709 colorspace.
-
-Transfer function. Note that negative values for L are only used by the
-Y'CbCr conversion.
-
-.. math::
-
- L' = -1.055(-L)^{\frac{1}{2.4} } + 0.055\text{, for }L < -0.0031308
-
- L' = 12.92L\text{, for }-0.0031308 \le L \le 0.0031308
-
- L' = 1.055L ^{\frac{1}{2.4} } - 0.055\text{, for }0.0031308 < L \le 1
-
-Inverse Transfer function:
-
-.. math::
-
- L = -((-L' + 0.055) / 1.055) ^{2.4}\text{, for }L' < -0.04045
-
- L = L' / 12.92\text{, for }-0.04045 \le L' \le 0.04045
-
- L = ((L' + 0.055) / 1.055) ^{2.4}\text{, for }L' > 0.04045
-
-The luminance (Y') and color difference (Cb and Cr) are obtained with
-the following ``V4L2_YCBCR_ENC_601`` encoding as defined by :ref:`sycc`:
-
-.. math::
-
- Y' = 0.2990R' + 0.5870G' + 0.1140B'
-
- Cb = -0.1687R' - 0.3313G' + 0.5B'
-
- Cr = 0.5R' - 0.4187G' - 0.0813B'
-
-Y' is clamped to the range [0…1] and Cb and Cr are clamped to the range
-[-0.5…0.5]. This transform is identical to one defined in SMPTE
-170M/BT.601. The Y'CbCr quantization is limited range.
-
-
-.. _col-oprgb:
-
-Colorspace opRGB (V4L2_COLORSPACE_OPRGB)
-===============================================
-
-The :ref:`oprgb` standard defines the colorspace used by computer
-graphics that use the opRGB colorspace. The default transfer function is
-``V4L2_XFER_FUNC_OPRGB``. The default Y'CbCr encoding is
-``V4L2_YCBCR_ENC_601``. The default Y'CbCr quantization is limited
-range.
-
-Note that the :ref:`oprgb` standard specifies full range quantization,
-however all current capture hardware supported by the kernel convert
-R'G'B' to limited range Y'CbCr. So choosing full range as the default
-would break how applications interpret the quantization range.
-
-The chromaticities of the primary colors and the white reference are:
-
-
-.. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.7cm}|
-
-.. flat-table:: opRGB Chromaticities
- :header-rows: 1
- :stub-columns: 0
- :widths: 1 1 2
-
- * - Color
- - x
- - y
- * - Red
- - 0.6400
- - 0.3300
- * - Green
- - 0.2100
- - 0.7100
- * - Blue
- - 0.1500
- - 0.0600
- * - White Reference (D65)
- - 0.3127
- - 0.3290
-
-
-
-Transfer function:
-
-.. math::
-
- L' = L ^{\frac{1}{2.19921875}}
-
-Inverse Transfer function:
-
-.. math::
-
- L = L'^{(2.19921875)}
-
-The luminance (Y') and color difference (Cb and Cr) are obtained with
-the following ``V4L2_YCBCR_ENC_601`` encoding:
-
-.. math::
-
- Y' = 0.2990R' + 0.5870G' + 0.1140B'
-
- Cb = -0.1687R' - 0.3313G' + 0.5B'
-
- Cr = 0.5R' - 0.4187G' - 0.0813B'
-
-Y' is clamped to the range [0…1] and Cb and Cr are clamped to the range
-[-0.5…0.5]. This transform is identical to one defined in SMPTE
-170M/BT.601. The Y'CbCr quantization is limited range.
-
-
-.. _col-bt2020:
-
-Colorspace BT.2020 (V4L2_COLORSPACE_BT2020)
-===========================================
-
-The :ref:`itu2020` standard defines the colorspace used by Ultra-high
-definition television (UHDTV). The default transfer function is
-``V4L2_XFER_FUNC_709``. The default Y'CbCr encoding is
-``V4L2_YCBCR_ENC_BT2020``. The default R'G'B' quantization is limited
-range (!), and so is the default Y'CbCr quantization. The chromaticities
-of the primary colors and the white reference are:
-
-
-
-.. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.7cm}|
-
-.. flat-table:: BT.2020 Chromaticities
- :header-rows: 1
- :stub-columns: 0
- :widths: 1 1 2
-
- * - Color
- - x
- - y
- * - Red
- - 0.708
- - 0.292
- * - Green
- - 0.170
- - 0.797
- * - Blue
- - 0.131
- - 0.046
- * - White Reference (D65)
- - 0.3127
- - 0.3290
-
-
-
-Transfer function (same as Rec. 709):
-
-.. math::
-
- L' = 4.5L\text{, for }0 \le L < 0.018
-
- L' = 1.099L ^{0.45} - 0.099\text{, for } 0.018 \le L \le 1
-
-Inverse Transfer function:
-
-.. math::
-
- L = L' / 4.5\text{, for } L' < 0.081
-
- L = \left( \frac{L' + 0.099}{1.099}\right) ^{\frac{1}{0.45} }\text{, for } L' \ge 0.081
-
-Please note that while Rec. 709 is defined as the default transfer function
-by the :ref:`itu2020` standard, in practice this colorspace is often used
-with the :ref:`xf-smpte-2084`. In particular Ultra HD Blu-ray discs use
-this combination.
-
-The luminance (Y') and color difference (Cb and Cr) are obtained with
-the following ``V4L2_YCBCR_ENC_BT2020`` encoding:
-
-.. math::
-
- Y' = 0.2627R' + 0.6780G' + 0.0593B'
-
- Cb = -0.1396R' - 0.3604G' + 0.5B'
-
- Cr = 0.5R' - 0.4598G' - 0.0402B'
-
-Y' is clamped to the range [0…1] and Cb and Cr are clamped to the range
-[-0.5…0.5]. The Y'CbCr quantization is limited range.
-
-There is also an alternate constant luminance R'G'B' to Yc'CbcCrc
-(``V4L2_YCBCR_ENC_BT2020_CONST_LUM``) encoding:
-
-Luma:
-
-.. math::
- :nowrap:
-
- \begin{align*}
- Yc' = (0.2627R + 0.6780G + 0.0593B)'& \\
- B' - Yc' \le 0:& \\
- &Cbc = (B' - Yc') / 1.9404 \\
- B' - Yc' > 0: & \\
- &Cbc = (B' - Yc') / 1.5816 \\
- R' - Yc' \le 0:& \\
- &Crc = (R' - Y') / 1.7184 \\
- R' - Yc' > 0:& \\
- &Crc = (R' - Y') / 0.9936
- \end{align*}
-
-Yc' is clamped to the range [0…1] and Cbc and Crc are clamped to the
-range [-0.5…0.5]. The Yc'CbcCrc quantization is limited range.
-
-
-.. _col-dcip3:
-
-Colorspace DCI-P3 (V4L2_COLORSPACE_DCI_P3)
-==========================================
-
-The :ref:`smpte431` standard defines the colorspace used by cinema
-projectors that use the DCI-P3 colorspace. The default transfer function
-is ``V4L2_XFER_FUNC_DCI_P3``. The default Y'CbCr encoding is
-``V4L2_YCBCR_ENC_709``. The default Y'CbCr quantization is limited range.
-
-.. note::
-
- Note that this colorspace standard does not specify a
- Y'CbCr encoding since it is not meant to be encoded to Y'CbCr. So this
- default Y'CbCr encoding was picked because it is the HDTV encoding.
-
-The chromaticities of the primary colors and the white reference are:
-
-
-
-.. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.7cm}|
-
-.. flat-table:: DCI-P3 Chromaticities
- :header-rows: 1
- :stub-columns: 0
- :widths: 1 1 2
-
- * - Color
- - x
- - y
- * - Red
- - 0.6800
- - 0.3200
- * - Green
- - 0.2650
- - 0.6900
- * - Blue
- - 0.1500
- - 0.0600
- * - White Reference
- - 0.3140
- - 0.3510
-
-
-
-Transfer function:
-
-.. math::
-
- L' = L^{\frac{1}{2.6}}
-
-Inverse Transfer function:
-
-.. math::
-
- L = L'^{(2.6)}
-
-Y'CbCr encoding is not specified. V4L2 defaults to Rec. 709.
-
-
-.. _col-smpte-240m:
-
-Colorspace SMPTE 240M (V4L2_COLORSPACE_SMPTE240M)
-=================================================
-
-The :ref:`smpte240m` standard was an interim standard used during the
-early days of HDTV (1988-1998). It has been superseded by Rec. 709. The
-default transfer function is ``V4L2_XFER_FUNC_SMPTE240M``. The default
-Y'CbCr encoding is ``V4L2_YCBCR_ENC_SMPTE240M``. The default Y'CbCr
-quantization is limited range. The chromaticities of the primary colors
-and the white reference are:
-
-
-
-.. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.7cm}|
-
-.. flat-table:: SMPTE 240M Chromaticities
- :header-rows: 1
- :stub-columns: 0
- :widths: 1 1 2
-
- * - Color
- - x
- - y
- * - Red
- - 0.630
- - 0.340
- * - Green
- - 0.310
- - 0.595
- * - Blue
- - 0.155
- - 0.070
- * - White Reference (D65)
- - 0.3127
- - 0.3290
-
-
-These chromaticities are identical to the SMPTE 170M colorspace.
-
-Transfer function:
-
-.. math::
-
- L' = 4L\text{, for } 0 \le L < 0.0228
-
- L' = 1.1115L ^{0.45} - 0.1115\text{, for } 0.0228 \le L \le 1
-
-Inverse Transfer function:
-
-.. math::
-
- L = \frac{L'}{4}\text{, for } 0 \le L' < 0.0913
-
- L = \left( \frac{L' + 0.1115}{1.1115}\right) ^{\frac{1}{0.45} }\text{, for } L' \ge 0.0913
-
-The luminance (Y') and color difference (Cb and Cr) are obtained with
-the following ``V4L2_YCBCR_ENC_SMPTE240M`` encoding:
-
-.. math::
-
- Y' = 0.2122R' + 0.7013G' + 0.0865B'
-
- Cb = -0.1161R' - 0.3839G' + 0.5B'
-
- Cr = 0.5R' - 0.4451G' - 0.0549B'
-
-Y' is clamped to the range [0…1] and Cb and Cr are clamped to the
-range [-0.5…0.5]. The Y'CbCr quantization is limited range.
-
-
-.. _col-sysm:
-
-Colorspace NTSC 1953 (V4L2_COLORSPACE_470_SYSTEM_M)
-===================================================
-
-This standard defines the colorspace used by NTSC in 1953. In practice
-this colorspace is obsolete and SMPTE 170M should be used instead. The
-default transfer function is ``V4L2_XFER_FUNC_709``. The default Y'CbCr
-encoding is ``V4L2_YCBCR_ENC_601``. The default Y'CbCr quantization is
-limited range. The chromaticities of the primary colors and the white
-reference are:
-
-
-
-.. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.7cm}|
-
-.. flat-table:: NTSC 1953 Chromaticities
- :header-rows: 1
- :stub-columns: 0
- :widths: 1 1 2
-
- * - Color
- - x
- - y
- * - Red
- - 0.67
- - 0.33
- * - Green
- - 0.21
- - 0.71
- * - Blue
- - 0.14
- - 0.08
- * - White Reference (C)
- - 0.310
- - 0.316
-
-
-.. note::
-
- This colorspace uses Illuminant C instead of D65 as the white
- reference. To correctly convert an image in this colorspace to another
- that uses D65 you need to apply a chromatic adaptation algorithm such as
- the Bradford method.
-
-The transfer function was never properly defined for NTSC 1953. The Rec.
-709 transfer function is recommended in the literature:
-
-.. math::
-
- L' = 4.5L\text{, for } 0 \le L < 0.018
-
- L' = 1.099L ^{0.45} - 0.099\text{, for } 0.018 \le L \le 1
-
-Inverse Transfer function:
-
-.. math::
-
- L = \frac{L'}{4.5} \text{, for } L' < 0.081
-
- L = \left( \frac{L' + 0.099}{1.099}\right) ^{\frac{1}{0.45} }\text{, for } L' \ge 0.081
-
-The luminance (Y') and color difference (Cb and Cr) are obtained with
-the following ``V4L2_YCBCR_ENC_601`` encoding:
-
-.. math::
-
- Y' = 0.2990R' + 0.5870G' + 0.1140B'
-
- Cb = -0.1687R' - 0.3313G' + 0.5B'
-
- Cr = 0.5R' - 0.4187G' - 0.0813B'
-
-Y' is clamped to the range [0…1] and Cb and Cr are clamped to the range
-[-0.5…0.5]. The Y'CbCr quantization is limited range. This transform is
-identical to one defined in SMPTE 170M/BT.601.
-
-
-.. _col-sysbg:
-
-Colorspace EBU Tech. 3213 (V4L2_COLORSPACE_470_SYSTEM_BG)
-=========================================================
-
-The :ref:`tech3213` standard defines the colorspace used by PAL/SECAM
-in 1975. In practice this colorspace is obsolete and SMPTE 170M should
-be used instead. The default transfer function is
-``V4L2_XFER_FUNC_709``. The default Y'CbCr encoding is
-``V4L2_YCBCR_ENC_601``. The default Y'CbCr quantization is limited
-range. The chromaticities of the primary colors and the white reference
-are:
-
-
-
-.. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.7cm}|
-
-.. flat-table:: EBU Tech. 3213 Chromaticities
- :header-rows: 1
- :stub-columns: 0
- :widths: 1 1 2
-
- * - Color
- - x
- - y
- * - Red
- - 0.64
- - 0.33
- * - Green
- - 0.29
- - 0.60
- * - Blue
- - 0.15
- - 0.06
- * - White Reference (D65)
- - 0.3127
- - 0.3290
-
-
-
-The transfer function was never properly defined for this colorspace.
-The Rec. 709 transfer function is recommended in the literature:
-
-.. math::
-
- L' = 4.5L\text{, for } 0 \le L < 0.018
-
- L' = 1.099L ^{0.45} - 0.099\text{, for } 0.018 \le L \le 1
-
-Inverse Transfer function:
-
-.. math::
-
- L = \frac{L'}{4.5} \text{, for } L' < 0.081
-
- L = \left(\frac{L' + 0.099}{1.099} \right) ^{\frac{1}{0.45} }\text{, for } L' \ge 0.081
-
-The luminance (Y') and color difference (Cb and Cr) are obtained with
-the following ``V4L2_YCBCR_ENC_601`` encoding:
-
-.. math::
-
- Y' = 0.2990R' + 0.5870G' + 0.1140B'
-
- Cb = -0.1687R' - 0.3313G' + 0.5B'
-
- Cr = 0.5R' - 0.4187G' - 0.0813B'
-
-Y' is clamped to the range [0…1] and Cb and Cr are clamped to the range
-[-0.5…0.5]. The Y'CbCr quantization is limited range. This transform is
-identical to one defined in SMPTE 170M/BT.601.
-
-
-.. _col-jpeg:
-
-Colorspace JPEG (V4L2_COLORSPACE_JPEG)
-======================================
-
-This colorspace defines the colorspace used by most (Motion-)JPEG
-formats. The chromaticities of the primary colors and the white
-reference are identical to sRGB. The transfer function use is
-``V4L2_XFER_FUNC_SRGB``. The Y'CbCr encoding is ``V4L2_YCBCR_ENC_601``
-with full range quantization where Y' is scaled to [0…255] and Cb/Cr are
-scaled to [-128…128] and then clipped to [-128…127].
-
-.. note::
-
- The JPEG standard does not actually store colorspace
- information. So if something other than sRGB is used, then the driver
- will have to set that information explicitly. Effectively
- ``V4L2_COLORSPACE_JPEG`` can be considered to be an abbreviation for
- ``V4L2_COLORSPACE_SRGB``, ``V4L2_YCBCR_ENC_601`` and
- ``V4L2_QUANTIZATION_FULL_RANGE``.
-
-***************************************
-Detailed Transfer Function Descriptions
-***************************************
-
-.. _xf-smpte-2084:
-
-Transfer Function SMPTE 2084 (V4L2_XFER_FUNC_SMPTE2084)
-=======================================================
-
-The :ref:`smpte2084` standard defines the transfer function used by
-High Dynamic Range content.
-
-Constants:
- m1 = (2610 / 4096) / 4
-
- m2 = (2523 / 4096) * 128
-
- c1 = 3424 / 4096
-
- c2 = (2413 / 4096) * 32
-
- c3 = (2392 / 4096) * 32
-
-Transfer function:
- L' = ((c1 + c2 * L\ :sup:`m1`) / (1 + c3 * L\ :sup:`m1`))\ :sup:`m2`
-
-Inverse Transfer function:
- L = (max(L':sup:`1/m2` - c1, 0) / (c2 - c3 *
- L'\ :sup:`1/m2`))\ :sup:`1/m1`
-
-Take care when converting between this transfer function and non-HDR transfer
-functions: the linear RGB values [0…1] of HDR content map to a luminance range
-of 0 to 10000 cd/m\ :sup:`2` whereas the linear RGB values of non-HDR (aka
-Standard Dynamic Range or SDR) map to a luminance range of 0 to 100 cd/m\ :sup:`2`.
-
-To go from SDR to HDR you will have to divide L by 100 first. To go in the other
-direction you will have to multiply L by 100. Of course, this clamps all
-luminance values over 100 cd/m\ :sup:`2` to 100 cd/m\ :sup:`2`.
-
-There are better methods, see e.g. :ref:`colimg` for more in-depth information
-about this.