From ddb5e9d37e05ec85da26aaf8be0442a5ca34280b Mon Sep 17 00:00:00 2001 From: David Plowman Date: Fri, 10 Dec 2021 14:44:17 +0000 Subject: libcamera: Add ColorSpace class This class represents a color space by defining its color primaries, the transfer (gamma) function it uses, the YCbCr encoding and whether the output is full or limited range. Signed-off-by: David Plowman Reviewed-by: Naushir Patuck Reviewed-by: Umang Jain Reviewed-by: Jacopo Mondi Reviewed-by: Laurent Pinchart Signed-off-by: Laurent Pinchart --- include/libcamera/color_space.h | 70 +++++++++ include/libcamera/meson.build | 1 + src/libcamera/color_space.cpp | 317 ++++++++++++++++++++++++++++++++++++++++ src/libcamera/meson.build | 1 + 4 files changed, 389 insertions(+) create mode 100644 include/libcamera/color_space.h create mode 100644 src/libcamera/color_space.cpp diff --git a/include/libcamera/color_space.h b/include/libcamera/color_space.h new file mode 100644 index 00000000..086c56c1 --- /dev/null +++ b/include/libcamera/color_space.h @@ -0,0 +1,70 @@ +/* SPDX-License-Identifier: LGPL-2.1-or-later */ +/* + * Copyright (C) 2021, Raspberry Pi (Trading) Limited + * + * color_space.h - color space definitions + */ + +#pragma once + +#include +#include + +namespace libcamera { + +class ColorSpace +{ +public: + enum class Primaries { + Raw, + Smpte170m, + Rec709, + Rec2020, + }; + + enum class TransferFunction { + Linear, + Srgb, + Rec709, + }; + + enum class YcbcrEncoding { + None, + Rec601, + Rec709, + Rec2020, + }; + + enum class Range { + Full, + Limited, + }; + + constexpr ColorSpace(Primaries p, TransferFunction t, YcbcrEncoding e, Range r) + : primaries(p), transferFunction(t), ycbcrEncoding(e), range(r) + { + } + + static const ColorSpace Raw; + static const ColorSpace Jpeg; + static const ColorSpace Srgb; + static const ColorSpace Smpte170m; + static const ColorSpace Rec709; + static const ColorSpace Rec2020; + + Primaries primaries; + TransferFunction transferFunction; + YcbcrEncoding ycbcrEncoding; + Range range; + + std::string toString() const; + static std::string toString(const std::optional &colorSpace); +}; + +bool operator==(const ColorSpace &lhs, const ColorSpace &rhs); +static inline bool operator!=(const ColorSpace &lhs, const ColorSpace &rhs) +{ + return !(lhs == rhs); +} + +} /* namespace libcamera */ diff --git a/include/libcamera/meson.build b/include/libcamera/meson.build index 8c2cae00..408b7acf 100644 --- a/include/libcamera/meson.build +++ b/include/libcamera/meson.build @@ -5,6 +5,7 @@ libcamera_include_dir = 'libcamera' / 'libcamera' libcamera_public_headers = files([ 'camera.h', 'camera_manager.h', + 'color_space.h', 'controls.h', 'fence.h', 'framebuffer.h', diff --git a/src/libcamera/color_space.cpp b/src/libcamera/color_space.cpp new file mode 100644 index 00000000..895e5c8e --- /dev/null +++ b/src/libcamera/color_space.cpp @@ -0,0 +1,317 @@ +/* SPDX-License-Identifier: LGPL-2.1-or-later */ +/* + * Copyright (C) 2021, Raspberry Pi (Trading) Limited + * + * color_space.cpp - color spaces. + */ + +#include + +#include +#include +#include +#include +#include + +/** + * \file color_space.h + * \brief Class and enums to represent color spaces + */ + +namespace libcamera { + +/** + * \class ColorSpace + * \brief Class to describe a color space + * + * The ColorSpace class defines the color primaries, the transfer function, + * the Y'CbCr encoding associated with the color space, and the range + * (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". + * + * 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: + * + * - sRGB + * - JPEG + * - SMPTE 170M + * - Rec.709 + * - Rec.2020 + */ + +/** + * \enum ColorSpace::Primaries + * \brief The color primaries for this color space + * + * \var ColorSpace::Primaries::Raw + * \brief These are raw colors directly from a sensor, the primaries are + * unspecified + * + * \var ColorSpace::Primaries::Smpte170m + * \brief SMPTE 170M color primaries + * + * \var ColorSpace::Primaries::Rec709 + * \brief Rec.709 color primaries + * + * \var ColorSpace::Primaries::Rec2020 + * \brief Rec.2020 color primaries + */ + +/** + * \enum ColorSpace::TransferFunction + * \brief The transfer function used for this color space + * + * \var ColorSpace::TransferFunction::Linear + * \brief This color space uses a linear (identity) transfer function + * + * \var ColorSpace::TransferFunction::Srgb + * \brief sRGB transfer function + * + * \var ColorSpace::TransferFunction::Rec709 + * \brief Rec.709 transfer function + */ + +/** + * \enum ColorSpace::YcbcrEncoding + * \brief The Y'CbCr encoding + * + * \var ColorSpace::YcbcrEncoding::None + * \brief There is no defined Y'CbCr encoding (used for non-YUV formats) + * + * \var ColorSpace::YcbcrEncoding::Rec601 + * \brief Rec.601 Y'CbCr encoding + * + * \var ColorSpace::YcbcrEncoding::Rec709 + * \brief Rec.709 Y'CbCr encoding + * + * \var ColorSpace::YcbcrEncoding::Rec2020 + * \brief Rec.2020 Y'CbCr encoding + */ + +/** + * \enum ColorSpace::Range + * \brief The range (sometimes "quantisation") for this color space + * + * \var ColorSpace::Range::Full + * \brief This color space uses full range pixel values + * + * \var ColorSpace::Range::Limited + * \brief This color space uses limited range pixel values, being + * 16 to 235 for Y' and 16 to 240 for Cb and Cr (8 bits per sample) + * or 64 to 940 for Y' and 16 to 960 for Cb and Cr (10 bits) + */ + +/** + * \fn ColorSpace::ColorSpace(Primaries p, TransferFunction t, Encoding e, Range r) + * \brief Construct a ColorSpace from explicit values + * \param[in] p The color primaries + * \param[in] t The transfer function for the color space + * \param[in] e The Y'CbCr encoding + * \param[in] r The range of the pixel values in this color space + */ + +/** + * \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 + * the four constituent parts of the ColorSpace are assembled into a longer + * string. + * + * \return A string describing the ColorSpace + */ +std::string ColorSpace::toString() const +{ + /* Print out a brief name only for standard color spaces. */ + + static const std::array, 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; + }); + if (it != colorSpaceNames.end()) + return std::string(it->second); + + /* Assemble a name made of the constituent fields. */ + + static const std::map primariesNames = { + { Primaries::Raw, "RAW" }, + { Primaries::Smpte170m, "SMPTE170M" }, + { Primaries::Rec709, "Rec709" }, + { Primaries::Rec2020, "Rec2020" }, + }; + static const std::map transferNames = { + { TransferFunction::Linear, "Linear" }, + { TransferFunction::Srgb, "sRGB" }, + { TransferFunction::Rec709, "Rec709" }, + }; + static const std::map encodingNames = { + { YcbcrEncoding::None, "None" }, + { YcbcrEncoding::Rec601, "Rec601" }, + { YcbcrEncoding::Rec709, "Rec709" }, + { YcbcrEncoding::Rec2020, "Rec2020" }, + }; + static const std::map rangeNames = { + { Range::Full, "Full" }, + { Range::Limited, "Limited" }, + }; + + auto itPrimaries = primariesNames.find(primaries); + std::string primariesName = + itPrimaries == primariesNames.end() ? "Invalid" : itPrimaries->second; + + auto itTransfer = transferNames.find(transferFunction); + std::string transferName = + itTransfer == transferNames.end() ? "Invalid" : itTransfer->second; + + auto itEncoding = encodingNames.find(ycbcrEncoding); + std::string encodingName = + itEncoding == encodingNames.end() ? "Invalid" : itEncoding->second; + + auto itRange = rangeNames.find(range); + std::string rangeName = + itRange == rangeNames.end() ? "Invalid" : itRange->second; + + std::stringstream ss; + ss << primariesName << "/" << transferName << "/" << encodingName << "/" << rangeName; + + return ss.str(); +} + +/** + * \brief Assemble and return a readable string representation of an + * optional ColorSpace + * + * This is a convenience helper to easily obtain a string representation + * for a ColorSpace in parts of the libcamera API where it is stored in a + * std::optional<>. If the ColorSpace is set, this function returns + * \a colorSpace.toString(), otherwise it returns "Unset". + * + * \return A string describing the optional ColorSpace + */ +std::string ColorSpace::toString(const std::optional &colorSpace) +{ + if (!colorSpace) + return "Unset"; + + return colorSpace->toString(); +} + +/** + * \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 + * + * 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 + */ +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 +}; + +/** + * \brief Compare color spaces for equality + * \return True if the two color spaces are identical, false otherwise + */ +bool operator==(const ColorSpace &lhs, const ColorSpace &rhs) +{ + return lhs.primaries == rhs.primaries && + lhs.transferFunction == rhs.transferFunction && + lhs.ycbcrEncoding == rhs.ycbcrEncoding && + lhs.range == rhs.range; +} + +/** + * \fn bool operator!=(const ColorSpace &lhs, const ColorSpace &rhs) + * \brief Compare color spaces for inequality + * \return True if the two color spaces are not identical, false otherwise + */ + +} /* namespace libcamera */ diff --git a/src/libcamera/meson.build b/src/libcamera/meson.build index dc1cc52a..7ae909d4 100644 --- a/src/libcamera/meson.build +++ b/src/libcamera/meson.build @@ -9,6 +9,7 @@ libcamera_sources = files([ 'camera_manager.cpp', 'camera_sensor.cpp', 'camera_sensor_properties.cpp', + 'color_space.cpp', 'controls.cpp', 'control_serializer.cpp', 'control_validator.cpp', -- cgit v1.2.1