diff options
Diffstat (limited to 'src/libcamera/color_space.cpp')
| -rw-r--r-- | src/libcamera/color_space.cpp | 101 |
1 files changed, 101 insertions, 0 deletions
diff --git a/src/libcamera/color_space.cpp b/src/libcamera/color_space.cpp index ec34620a..7356bf7d 100644 --- a/src/libcamera/color_space.cpp +++ b/src/libcamera/color_space.cpp @@ -16,6 +16,8 @@ #include <libcamera/base/utils.h> +#include "libcamera/internal/formats.h" + /** * \file color_space.h * \brief Class and enums to represent color spaces @@ -399,6 +401,105 @@ std::optional<ColorSpace> ColorSpace::fromString(const std::string &str) } /** + * \brief Adjust the color space to match a pixel format + * \param[in] format The pixel format + * + * Not all combinations of pixel formats and color spaces make sense. For + * instance, nobody uses a limited quantization range with raw Bayer formats, + * and the YcbcrEncoding::None encoding isn't valid for YUV formats. This + * function adjusts the ColorSpace to make it compatible with the given \a + * format, by applying the following rules: + * + * - The color space for RAW formats must be Raw. + * - The Y'CbCr encoding and quantization range for RGB formats must be + * YcbcrEncoding::None and Range::Full respectively. + * - The Y'CbCr encoding for YUV formats must not be YcbcrEncoding::None. The + * best encoding is in that case guessed based on the primaries and transfer + * function. + * + * \return True if the color space has been adjusted, or false if it was + * already compatible with the format and hasn't been changed + */ +bool ColorSpace::adjust(PixelFormat format) +{ + const PixelFormatInfo &info = PixelFormatInfo::info(format); + bool adjusted = false; + + switch (info.colourEncoding) { + case PixelFormatInfo::ColourEncodingRAW: + /* Raw formats must use the raw color space. */ + if (*this != ColorSpace::Raw) { + *this = ColorSpace::Raw; + adjusted = true; + } + break; + + case PixelFormatInfo::ColourEncodingRGB: + /* + * RGB formats can't have a Y'CbCr encoding, and must use full + * range quantization. + */ + if (ycbcrEncoding != YcbcrEncoding::None) { + ycbcrEncoding = YcbcrEncoding::None; + adjusted = true; + } + + if (range != Range::Full) { + range = Range::Full; + adjusted = true; + } + break; + + case PixelFormatInfo::ColourEncodingYUV: + if (ycbcrEncoding != YcbcrEncoding::None) + break; + + /* + * YUV formats must have a Y'CbCr encoding. Infer the most + * probable option from the transfer function and primaries. + */ + switch (transferFunction) { + case TransferFunction::Linear: + /* + * Linear YUV is not used in any standard color space, + * pick the widely supported and used Rec601 as default. + */ + ycbcrEncoding = YcbcrEncoding::Rec601; + break; + + case TransferFunction::Rec709: + switch (primaries) { + /* Raw should never happen. */ + case Primaries::Raw: + case Primaries::Smpte170m: + ycbcrEncoding = YcbcrEncoding::Rec601; + break; + case Primaries::Rec709: + ycbcrEncoding = YcbcrEncoding::Rec709; + break; + case Primaries::Rec2020: + ycbcrEncoding = YcbcrEncoding::Rec2020; + break; + } + break; + + case TransferFunction::Srgb: + /* + * Only the sYCC color space uses the sRGB transfer + * function, the corresponding encoding is Rec601. + */ + ycbcrEncoding = YcbcrEncoding::Rec601; + break; + } + + adjusted = true; + break; + } + + return adjusted; +} + +/** * \brief Compare color spaces for equality * \return True if the two color spaces are identical, false otherwise */ |