diff options
Diffstat (limited to 'src/libcamera/color_space.cpp')
| -rw-r--r-- | src/libcamera/color_space.cpp | 429 |
1 files changed, 316 insertions, 113 deletions
diff --git a/src/libcamera/color_space.cpp b/src/libcamera/color_space.cpp index 895e5c8e..7356bf7d 100644 --- a/src/libcamera/color_space.cpp +++ b/src/libcamera/color_space.cpp @@ -1,6 +1,6 @@ /* SPDX-License-Identifier: LGPL-2.1-or-later */ /* - * Copyright (C) 2021, Raspberry Pi (Trading) Limited + * Copyright (C) 2021, Raspberry Pi Ltd * * color_space.cpp - color spaces. */ @@ -12,6 +12,11 @@ #include <map> #include <sstream> #include <utility> +#include <vector> + +#include <libcamera/base/utils.h> + +#include "libcamera/internal/formats.h" /** * \file color_space.h @@ -29,21 +34,33 @@ namespace libcamera { * (sometimes also referred to as the quantisation) of the color space. * * Certain combinations of these fields form well-known standard color - * spaces such as "JPEG" or "REC709". + * spaces such as "sRGB" or "Rec709". * * In the strictest sense a "color space" formally only refers to the * color primaries and white point. Here, however, the ColorSpace class * adopts the common broader usage that includes the transfer function, * Y'CbCr encoding method and quantisation. * - * For more information on the specific color spaces described here, please - * see: + * More information on color spaces is available in the V4L2 documentation, see + * in particular * * - <a href="https://www.kernel.org/doc/html/latest/userspace-api/media/v4l/colorspaces-details.html#col-srgb">sRGB</a> * - <a href="https://www.kernel.org/doc/html/latest/userspace-api/media/v4l/colorspaces-details.html#col-jpeg">JPEG</a> * - <a href="https://www.kernel.org/doc/html/latest/userspace-api/media/v4l/colorspaces-details.html#col-smpte-170m">SMPTE 170M</a> * - <a href="https://www.kernel.org/doc/html/latest/userspace-api/media/v4l/colorspaces-details.html#col-rec709">Rec.709</a> * - <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. 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 */ /** @@ -118,11 +135,130 @@ namespace libcamera { */ /** + * \brief A constant representing a raw color space (from a sensor) + */ +const ColorSpace ColorSpace::Raw = { + Primaries::Raw, + TransferFunction::Linear, + YcbcrEncoding::None, + Range::Full +}; + +/** + * \brief A constant representing the sRGB color space (RGB formats only) + */ +const ColorSpace ColorSpace::Srgb = { + Primaries::Rec709, + TransferFunction::Srgb, + YcbcrEncoding::None, + Range::Full +}; + +/** + * \brief A constant representing the sYCC color space, typically used for + * encoding JPEG images + */ +const ColorSpace ColorSpace::Sycc = { + Primaries::Rec709, + TransferFunction::Srgb, + YcbcrEncoding::Rec601, + Range::Full +}; + +/** + * \brief A constant representing the SMPTE170M color space + */ +const ColorSpace ColorSpace::Smpte170m = { + Primaries::Smpte170m, + TransferFunction::Rec709, + YcbcrEncoding::Rec601, + Range::Limited +}; + +/** + * \brief A constant representing the Rec.709 color space + */ +const ColorSpace ColorSpace::Rec709 = { + Primaries::Rec709, + TransferFunction::Rec709, + YcbcrEncoding::Rec709, + Range::Limited +}; + +/** + * \brief A constant representing the Rec.2020 color space + */ +const ColorSpace ColorSpace::Rec2020 = { + Primaries::Rec2020, + TransferFunction::Rec709, + YcbcrEncoding::Rec2020, + Range::Limited +}; + +/** + * \var ColorSpace::primaries + * \brief The color primaries of this color space + */ + +/** + * \var ColorSpace::transferFunction + * \brief The transfer function used by this color space + */ + +/** + * \var ColorSpace::ycbcrEncoding + * \brief The Y'CbCr encoding used by this color space + */ + +/** + * \var ColorSpace::range + * \brief The pixel range used with by color space + */ + +namespace { + +const std::array<std::pair<ColorSpace, const char *>, 6> colorSpaceNames = { { + { ColorSpace::Raw, "RAW" }, + { ColorSpace::Srgb, "sRGB" }, + { ColorSpace::Sycc, "sYCC" }, + { ColorSpace::Smpte170m, "SMPTE170M" }, + { ColorSpace::Rec709, "Rec709" }, + { ColorSpace::Rec2020, "Rec2020" }, +} }; + +const std::map<ColorSpace::Primaries, std::string> primariesNames = { + { ColorSpace::Primaries::Raw, "RAW" }, + { ColorSpace::Primaries::Smpte170m, "SMPTE170M" }, + { ColorSpace::Primaries::Rec709, "Rec709" }, + { ColorSpace::Primaries::Rec2020, "Rec2020" }, +}; + +const std::map<ColorSpace::TransferFunction, std::string> transferNames = { + { ColorSpace::TransferFunction::Linear, "Linear" }, + { ColorSpace::TransferFunction::Srgb, "sRGB" }, + { ColorSpace::TransferFunction::Rec709, "Rec709" }, +}; + +const std::map<ColorSpace::YcbcrEncoding, std::string> encodingNames = { + { ColorSpace::YcbcrEncoding::None, "None" }, + { ColorSpace::YcbcrEncoding::Rec601, "Rec601" }, + { ColorSpace::YcbcrEncoding::Rec709, "Rec709" }, + { ColorSpace::YcbcrEncoding::Rec2020, "Rec2020" }, +}; + +const std::map<ColorSpace::Range, std::string> rangeNames = { + { ColorSpace::Range::Full, "Full" }, + { ColorSpace::Range::Limited, "Limited" }, +}; + +} /* namespace */ + +/** * \brief Assemble and return a readable string representation of the * ColorSpace * - * If the color space matches a standard ColorSpace (such as ColorSpace::Jpeg) - * then the short name of the color space ("JPEG") is returned. Otherwise + * If the color space matches a standard ColorSpace (such as ColorSpace::Sycc) + * then the short name of the color space ("sYCC") is returned. Otherwise * the four constituent parts of the ColorSpace are assembled into a longer * string. * @@ -132,14 +268,6 @@ std::string ColorSpace::toString() const { /* Print out a brief name only for standard color spaces. */ - static const std::array<std::pair<ColorSpace, const char *>, 6> colorSpaceNames = { { - { ColorSpace::Raw, "RAW" }, - { ColorSpace::Jpeg, "JPEG" }, - { ColorSpace::Srgb, "sRGB" }, - { ColorSpace::Smpte170m, "SMPTE170M" }, - { ColorSpace::Rec709, "Rec709" }, - { ColorSpace::Rec2020, "Rec2020" }, - } }; auto it = std::find_if(colorSpaceNames.begin(), colorSpaceNames.end(), [this](const auto &item) { return *this == item.first; @@ -149,28 +277,6 @@ std::string ColorSpace::toString() const /* Assemble a name made of the constituent fields. */ - static const std::map<Primaries, std::string> primariesNames = { - { Primaries::Raw, "RAW" }, - { Primaries::Smpte170m, "SMPTE170M" }, - { Primaries::Rec709, "Rec709" }, - { Primaries::Rec2020, "Rec2020" }, - }; - static const std::map<TransferFunction, std::string> transferNames = { - { TransferFunction::Linear, "Linear" }, - { TransferFunction::Srgb, "sRGB" }, - { TransferFunction::Rec709, "Rec709" }, - }; - static const std::map<YcbcrEncoding, std::string> encodingNames = { - { YcbcrEncoding::None, "None" }, - { YcbcrEncoding::Rec601, "Rec601" }, - { YcbcrEncoding::Rec709, "Rec709" }, - { YcbcrEncoding::Rec2020, "Rec2020" }, - }; - static const std::map<Range, std::string> rangeNames = { - { Range::Full, "Full" }, - { Range::Limited, "Limited" }, - }; - auto itPrimaries = primariesNames.find(primaries); std::string primariesName = itPrimaries == primariesNames.end() ? "Invalid" : itPrimaries->second; @@ -213,88 +319,185 @@ std::string ColorSpace::toString(const std::optional<ColorSpace> &colorSpace) } /** - * \var ColorSpace::primaries - * \brief The color primaries of this color space - */ - -/** - * \var ColorSpace::transferFunction - * \brief The transfer function used by this color space - */ - -/** - * \var ColorSpace::ycbcrEncoding - * \brief The Y'CbCr encoding used by this color space - */ - -/** - * \var ColorSpace::range - * \brief The pixel range used with by color space - */ - -/** - * \brief A constant representing a raw color space (from a sensor) - */ -const ColorSpace ColorSpace::Raw = { - Primaries::Raw, - TransferFunction::Linear, - YcbcrEncoding::None, - Range::Full -}; - -/** - * \brief A constant representing the JPEG color space used for - * encoding JPEG images - */ -const ColorSpace ColorSpace::Jpeg = { - Primaries::Rec709, - TransferFunction::Srgb, - YcbcrEncoding::Rec601, - Range::Full -}; - -/** - * \brief A constant representing the sRGB color space + * \brief Construct a color space from a string + * \param[in] str The string * - * This is identical to the JPEG color space except that the Y'CbCr - * range is limited rather than full. - */ -const ColorSpace ColorSpace::Srgb = { - Primaries::Rec709, - TransferFunction::Srgb, - YcbcrEncoding::Rec601, - Range::Limited -}; - -/** - * \brief A constant representing the SMPTE170M color space - */ -const ColorSpace ColorSpace::Smpte170m = { - Primaries::Smpte170m, - TransferFunction::Rec709, - YcbcrEncoding::Rec601, - Range::Limited -}; - -/** - * \brief A constant representing the Rec.709 color space + * The string \a str can contain the name of a well-known color space, or be + * made of the four color space components separated by a '/' character, ordered + * as + * + * \verbatim primaries '/' transferFunction '/' ycbcrEncoding '/' range \endverbatim + * + * Any failure to parse the string, either because it doesn't match the expected + * format, or because the one of the names isn't recognized, will cause this + * function to return std::nullopt. + * + * \return The ColorSpace corresponding to the string, or std::nullopt if the + * string doesn't describe a known color space */ -const ColorSpace ColorSpace::Rec709 = { - Primaries::Rec709, - TransferFunction::Rec709, - YcbcrEncoding::Rec709, - Range::Limited -}; +std::optional<ColorSpace> ColorSpace::fromString(const std::string &str) +{ + /* First search for a standard color space name match. */ + auto itColorSpace = std::find_if(colorSpaceNames.begin(), colorSpaceNames.end(), + [&str](const auto &item) { + return str == item.second; + }); + if (itColorSpace != colorSpaceNames.end()) + return itColorSpace->first; + + /* + * If not found, the string must contain the four color space + * components separated by a '/' character. + */ + const auto &split = utils::split(str, "/"); + std::vector<std::string> components{ split.begin(), split.end() }; + + if (components.size() != 4) + return std::nullopt; + + ColorSpace colorSpace = ColorSpace::Raw; + + /* Color primaries */ + auto itPrimaries = std::find_if(primariesNames.begin(), primariesNames.end(), + [&components](const auto &item) { + return components[0] == item.second; + }); + if (itPrimaries == primariesNames.end()) + return std::nullopt; + + colorSpace.primaries = itPrimaries->first; + + /* Transfer function */ + auto itTransfer = std::find_if(transferNames.begin(), transferNames.end(), + [&components](const auto &item) { + return components[1] == item.second; + }); + if (itTransfer == transferNames.end()) + return std::nullopt; + + colorSpace.transferFunction = itTransfer->first; + + /* YCbCr encoding */ + auto itEncoding = std::find_if(encodingNames.begin(), encodingNames.end(), + [&components](const auto &item) { + return components[2] == item.second; + }); + if (itEncoding == encodingNames.end()) + return std::nullopt; + + colorSpace.ycbcrEncoding = itEncoding->first; + + /* Quantization range */ + auto itRange = std::find_if(rangeNames.begin(), rangeNames.end(), + [&components](const auto &item) { + return components[3] == item.second; + }); + if (itRange == rangeNames.end()) + return std::nullopt; + + colorSpace.range = itRange->first; + + return colorSpace; +} /** - * \brief A constant representing the Rec.2020 color space + * \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 */ -const ColorSpace ColorSpace::Rec2020 = { - Primaries::Rec2020, - TransferFunction::Rec709, - YcbcrEncoding::Rec2020, - Range::Limited -}; +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 |