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+.. -*- coding: utf-8; mode: rst -*-
+
+****************************
+Defining Colorspaces in V4L2
+****************************
+
+In V4L2 colorspaces are defined by four values. The first is the
+colorspace identifier (enum :ref:`v4l2_colorspace <v4l2-colorspace>`)
+which defines the chromaticities, the default transfer function, the
+default Y'CbCr encoding and the default quantization method. The second
+is the transfer function identifier (enum
+:ref:`v4l2_xfer_func <v4l2-xfer-func>`) to specify non-standard
+transfer functions. The third is the Y'CbCr encoding identifier (enum
+:ref:`v4l2_ycbcr_encoding <v4l2-ycbcr-encoding>`) to specify
+non-standard Y'CbCr encodings and the fourth is the quantization
+identifier (enum :ref:`v4l2_quantization <v4l2-quantization>`) to
+specify non-standard quantization methods. Most of the time only the
+colorspace field of struct :ref:`v4l2_pix_format <v4l2-pix-format>`
+or struct :ref:`v4l2_pix_format_mplane <v4l2-pix-format-mplane>`
+needs to be filled in.
+
+.. note:: The default R'G'B' quantization is full range for all
+ colorspaces except for BT.2020 which uses limited range R'G'B'
+ quantization.
+
+
+.. _v4l2-colorspace:
+
+.. flat-table:: V4L2 Colorspaces
+ :header-rows: 1
+ :stub-columns: 0
+
+
+ - .. row 1
+
+ - Identifier
+
+ - Details
+
+ - .. row 2
+
+ - ``V4L2_COLORSPACE_DEFAULT``
+
+ - The default colorspace. This can be used by applications to let
+ the driver fill in the colorspace.
+
+ - .. row 3
+
+ - ``V4L2_COLORSPACE_SMPTE170M``
+
+ - See :ref:`col-smpte-170m`.
+
+ - .. row 4
+
+ - ``V4L2_COLORSPACE_REC709``
+
+ - See :ref:`col-rec709`.
+
+ - .. row 5
+
+ - ``V4L2_COLORSPACE_SRGB``
+
+ - See :ref:`col-srgb`.
+
+ - .. row 6
+
+ - ``V4L2_COLORSPACE_ADOBERGB``
+
+ - See :ref:`col-adobergb`.
+
+ - .. row 7
+
+ - ``V4L2_COLORSPACE_BT2020``
+
+ - See :ref:`col-bt2020`.
+
+ - .. row 8
+
+ - ``V4L2_COLORSPACE_DCI_P3``
+
+ - See :ref:`col-dcip3`.
+
+ - .. row 9
+
+ - ``V4L2_COLORSPACE_SMPTE240M``
+
+ - See :ref:`col-smpte-240m`.
+
+ - .. row 10
+
+ - ``V4L2_COLORSPACE_470_SYSTEM_M``
+
+ - See :ref:`col-sysm`.
+
+ - .. row 11
+
+ - ``V4L2_COLORSPACE_470_SYSTEM_BG``
+
+ - See :ref:`col-sysbg`.
+
+ - .. row 12
+
+ - ``V4L2_COLORSPACE_JPEG``
+
+ - See :ref:`col-jpeg`.
+
+ - .. row 13
+
+ - ``V4L2_COLORSPACE_RAW``
+
+ - The raw colorspace. This is used for raw image capture where the
+ image is minimally processed and is using the internal colorspace
+ of the device. The software that processes an image using this
+ 'colorspace' will have to know the internals of the capture
+ device.
+
+
+
+.. _v4l2-xfer-func:
+
+.. flat-table:: V4L2 Transfer Function
+ :header-rows: 1
+ :stub-columns: 0
+
+
+ - .. row 1
+
+ - Identifier
+
+ - Details
+
+ - .. row 2
+
+ - ``V4L2_XFER_FUNC_DEFAULT``
+
+ - Use the default transfer function as defined by the colorspace.
+
+ - .. row 3
+
+ - ``V4L2_XFER_FUNC_709``
+
+ - Use the Rec. 709 transfer function.
+
+ - .. row 4
+
+ - ``V4L2_XFER_FUNC_SRGB``
+
+ - Use the sRGB transfer function.
+
+ - .. row 5
+
+ - ``V4L2_XFER_FUNC_ADOBERGB``
+
+ - Use the AdobeRGB transfer function.
+
+ - .. row 6
+
+ - ``V4L2_XFER_FUNC_SMPTE240M``
+
+ - Use the SMPTE 240M transfer function.
+
+ - .. row 7
+
+ - ``V4L2_XFER_FUNC_NONE``
+
+ - Do not use a transfer function (i.e. use linear RGB values).
+
+ - .. row 8
+
+ - ``V4L2_XFER_FUNC_DCI_P3``
+
+ - Use the DCI-P3 transfer function.
+
+ - .. row 9
+
+ - ``V4L2_XFER_FUNC_SMPTE2084``
+
+ - Use the SMPTE 2084 transfer function.
+
+
+
+.. _v4l2-ycbcr-encoding:
+
+.. flat-table:: V4L2 Y'CbCr Encodings
+ :header-rows: 1
+ :stub-columns: 0
+
+
+ - .. row 1
+
+ - Identifier
+
+ - Details
+
+ - .. row 2
+
+ - ``V4L2_YCBCR_ENC_DEFAULT``
+
+ - Use the default Y'CbCr encoding as defined by the colorspace.
+
+ - .. row 3
+
+ - ``V4L2_YCBCR_ENC_601``
+
+ - Use the BT.601 Y'CbCr encoding.
+
+ - .. row 4
+
+ - ``V4L2_YCBCR_ENC_709``
+
+ - Use the Rec. 709 Y'CbCr encoding.
+
+ - .. row 5
+
+ - ``V4L2_YCBCR_ENC_XV601``
+
+ - Use the extended gamut xvYCC BT.601 encoding.
+
+ - .. row 6
+
+ - ``V4L2_YCBCR_ENC_XV709``
+
+ - Use the extended gamut xvYCC Rec. 709 encoding.
+
+ - .. row 7
+
+ - ``V4L2_YCBCR_ENC_SYCC``
+
+ - Use the extended gamut sYCC encoding.
+
+ - .. row 8
+
+ - ``V4L2_YCBCR_ENC_BT2020``
+
+ - Use the default non-constant luminance BT.2020 Y'CbCr encoding.
+
+ - .. row 9
+
+ - ``V4L2_YCBCR_ENC_BT2020_CONST_LUM``
+
+ - Use the constant luminance BT.2020 Yc'CbcCrc encoding.
+
+ - .. row 10
+
+ - ``V4L2_YCBCR_ENC_SMPTE_240M``
+
+ - Use the SMPTE 240M Y'CbCr encoding.
+
+
+
+.. _v4l2-quantization:
+
+.. flat-table:: V4L2 Quantization Methods
+ :header-rows: 1
+ :stub-columns: 0
+
+
+ - .. row 1
+
+ - Identifier
+
+ - Details
+
+ - .. row 2
+
+ - ``V4L2_QUANTIZATION_DEFAULT``
+
+ - Use the default quantization encoding as defined by the
+ colorspace. This is always full range for R'G'B' (except for the
+ BT.2020 colorspace) and usually limited range for Y'CbCr.
+
+ - .. row 3
+
+ - ``V4L2_QUANTIZATION_FULL_RANGE``
+
+ - Use the full range quantization encoding. I.e. the range [0…1] is
+ mapped to [0…255] (with possible clipping to [1…254] to avoid the
+ 0x00 and 0xff values). Cb and Cr are mapped from [-0.5…0.5] to
+ [0…255] (with possible clipping to [1…254] to avoid the 0x00 and
+ 0xff values).
+
+ - .. row 4
+
+ - ``V4L2_QUANTIZATION_LIM_RANGE``
+
+ - Use the limited range quantization encoding. I.e. the range [0…1]
+ is mapped to [16…235]. Cb and Cr are mapped from [-0.5…0.5] to
+ [16…240].
generated by cgit v1.2.3 (git 2.0.4) at 2024-11-10 03:27:12 +0000