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authorUmang Jain <umang.jain@ideasonboard.com>2022-08-30 13:17:22 +0530
committerUmang Jain <umang.jain@ideasonboard.com>2022-09-01 16:49:59 +0530
commitd09c2bb127d5f96f4f397bd3ca11839840888b46 (patch)
tree489e3cb376e280a6d76dfe7ed5a658a258590495 /src/libcamera
parente52729e7ec3f735b0078b70e25e5daf2e051c429 (diff)
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>
Diffstat (limited to 'src/libcamera')
-rw-r--r--src/libcamera/color_space.cpp18
-rw-r--r--src/libcamera/v4l2_device.cpp7
2 files changed, 15 insertions, 10 deletions
diff --git a/src/libcamera/color_space.cpp b/src/libcamera/color_space.cpp
index 944d0e98..ec34620a 100644
--- a/src/libcamera/color_space.cpp
+++ b/src/libcamera/color_space.cpp
@@ -49,8 +49,13 @@ namespace libcamera {
* - <a href="https://www.kernel.org/doc/html/latest/userspace-api/media/v4l/colorspaces-details.html#col-bt2020">Rec.2020</a>
*
* Note that there is no guarantee of a 1:1 mapping between color space names
- * and definitions in libcamera and V4L2. A notable difference is that the sYCC
- * libcamera color space is called JPEG in V4L2 due to historical reasons.
+ * and definitions in libcamera and V4L2. Two notable differences are
+ *
+ * - The sRGB libcamera color space is defined for RGB formats only with no
+ * Y'CbCr encoding and a full quantization range, while the V4L2 SRGB color
+ * space has a Y'CbCr encoding and a limited quantization range.
+ * - The sYCC libcamera color space is called JPEG in V4L2 due to historical
+ * reasons.
*
* \todo Define the color space fully in the libcamera API to avoid referencing
* V4L2
@@ -138,16 +143,13 @@ const ColorSpace ColorSpace::Raw = {
};
/**
- * \brief A constant representing the sRGB color space
- *
- * This is identical to the sYCC color space except that the Y'CbCr
- * range is limited rather than full.
+ * \brief A constant representing the sRGB color space (RGB formats only)
*/
const ColorSpace ColorSpace::Srgb = {
Primaries::Rec709,
TransferFunction::Srgb,
- YcbcrEncoding::Rec601,
- Range::Limited
+ YcbcrEncoding::None,
+ Range::Full
};
/**
diff --git a/src/libcamera/v4l2_device.cpp b/src/libcamera/v4l2_device.cpp
index 301620f8..1d899657 100644
--- a/src/libcamera/v4l2_device.cpp
+++ b/src/libcamera/v4l2_device.cpp
@@ -746,7 +746,11 @@ void V4L2Device::eventAvailable()
static const std::map<uint32_t, ColorSpace> v4l2ToColorSpace = {
{ V4L2_COLORSPACE_RAW, ColorSpace::Raw },
- { V4L2_COLORSPACE_SRGB, ColorSpace::Srgb },
+ { V4L2_COLORSPACE_SRGB, {
+ ColorSpace::Primaries::Rec709,
+ ColorSpace::TransferFunction::Srgb,
+ ColorSpace::YcbcrEncoding::Rec601,
+ ColorSpace::Range::Limited } },
{ V4L2_COLORSPACE_JPEG, ColorSpace::Sycc },
{ V4L2_COLORSPACE_SMPTE170M, ColorSpace::Smpte170m },
{ V4L2_COLORSPACE_REC709, ColorSpace::Rec709 },
@@ -772,7 +776,6 @@ static const std::map<uint32_t, ColorSpace::Range> v4l2ToRange = {
static const std::vector<std::pair<ColorSpace, v4l2_colorspace>> colorSpaceToV4l2 = {
{ ColorSpace::Raw, V4L2_COLORSPACE_RAW },
- { ColorSpace::Srgb, V4L2_COLORSPACE_SRGB },
{ ColorSpace::Sycc, V4L2_COLORSPACE_JPEG },
{ ColorSpace::Smpte170m, V4L2_COLORSPACE_SMPTE170M },
{ ColorSpace::Rec709, V4L2_COLORSPACE_REC709 },

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