libcamera: colorspace: Rectify the ColorSpace::Srgb preset
Rectify the ColorSpace::Srgb to denote that it does not use any Y'Cbcr encoding and uses full range. The kernel on the other hand, recommends to use Rec601 as the encoding for V4L2_COLORSPACE_SRGB. It is not very explicit but it can be inferred that the kernel assumes V4L2_COLORSPACE_SRGB is a YUV-encoded one. However, when the data is in RGB, no encoding is required (and this is denoted by YcbcrEncoding::None in libcamera). Hence, to be clear on the libcamera colorspace API, rectify the ColorSpace::Srgb preset to use YcbcrEncoding::None and full range. Signed-off-by: Umang Jain <umang.jain@ideasonboard.com> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Reviewed-by: Paul Elder <paul.elder@ideasonboard.com>
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2 changed files with 15 additions and 10 deletions
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@ -49,8 +49,13 @@ namespace libcamera {
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* - <a href="https://www.kernel.org/doc/html/latest/userspace-api/media/v4l/colorspaces-details.html#col-bt2020">Rec.2020</a>
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* - <a href="https://www.kernel.org/doc/html/latest/userspace-api/media/v4l/colorspaces-details.html#col-bt2020">Rec.2020</a>
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*
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*
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* Note that there is no guarantee of a 1:1 mapping between color space names
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* Note that there is no guarantee of a 1:1 mapping between color space names
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* and definitions in libcamera and V4L2. A notable difference is that the sYCC
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* and definitions in libcamera and V4L2. Two notable differences are
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* libcamera color space is called JPEG in V4L2 due to historical reasons.
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*
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* - The sRGB libcamera color space is defined for RGB formats only with no
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* Y'CbCr encoding and a full quantization range, while the V4L2 SRGB color
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* space has a Y'CbCr encoding and a limited quantization range.
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* - The sYCC libcamera color space is called JPEG in V4L2 due to historical
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* reasons.
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*
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*
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* \todo Define the color space fully in the libcamera API to avoid referencing
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* \todo Define the color space fully in the libcamera API to avoid referencing
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* V4L2
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* V4L2
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@ -138,16 +143,13 @@ const ColorSpace ColorSpace::Raw = {
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};
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};
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/**
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/**
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* \brief A constant representing the sRGB color space
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* \brief A constant representing the sRGB color space (RGB formats only)
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*
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* This is identical to the sYCC color space except that the Y'CbCr
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* range is limited rather than full.
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*/
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*/
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const ColorSpace ColorSpace::Srgb = {
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const ColorSpace ColorSpace::Srgb = {
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Primaries::Rec709,
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Primaries::Rec709,
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TransferFunction::Srgb,
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TransferFunction::Srgb,
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YcbcrEncoding::Rec601,
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YcbcrEncoding::None,
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Range::Limited
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Range::Full
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};
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};
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/**
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/**
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@ -746,7 +746,11 @@ void V4L2Device::eventAvailable()
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static const std::map<uint32_t, ColorSpace> v4l2ToColorSpace = {
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static const std::map<uint32_t, ColorSpace> v4l2ToColorSpace = {
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{ V4L2_COLORSPACE_RAW, ColorSpace::Raw },
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{ V4L2_COLORSPACE_RAW, ColorSpace::Raw },
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{ V4L2_COLORSPACE_SRGB, ColorSpace::Srgb },
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{ V4L2_COLORSPACE_SRGB, {
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ColorSpace::Primaries::Rec709,
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ColorSpace::TransferFunction::Srgb,
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ColorSpace::YcbcrEncoding::Rec601,
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ColorSpace::Range::Limited } },
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{ V4L2_COLORSPACE_JPEG, ColorSpace::Sycc },
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{ V4L2_COLORSPACE_JPEG, ColorSpace::Sycc },
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{ V4L2_COLORSPACE_SMPTE170M, ColorSpace::Smpte170m },
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{ V4L2_COLORSPACE_SMPTE170M, ColorSpace::Smpte170m },
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{ V4L2_COLORSPACE_REC709, ColorSpace::Rec709 },
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{ V4L2_COLORSPACE_REC709, ColorSpace::Rec709 },
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@ -772,7 +776,6 @@ static const std::map<uint32_t, ColorSpace::Range> v4l2ToRange = {
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static const std::vector<std::pair<ColorSpace, v4l2_colorspace>> colorSpaceToV4l2 = {
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static const std::vector<std::pair<ColorSpace, v4l2_colorspace>> colorSpaceToV4l2 = {
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{ ColorSpace::Raw, V4L2_COLORSPACE_RAW },
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{ ColorSpace::Raw, V4L2_COLORSPACE_RAW },
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{ ColorSpace::Srgb, V4L2_COLORSPACE_SRGB },
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{ ColorSpace::Sycc, V4L2_COLORSPACE_JPEG },
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{ ColorSpace::Sycc, V4L2_COLORSPACE_JPEG },
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{ ColorSpace::Smpte170m, V4L2_COLORSPACE_SMPTE170M },
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{ ColorSpace::Smpte170m, V4L2_COLORSPACE_SMPTE170M },
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{ ColorSpace::Rec709, V4L2_COLORSPACE_REC709 },
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{ ColorSpace::Rec709, V4L2_COLORSPACE_REC709 },
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