[libcamera-devel] [PATCH v6 1/7] libcamera: Add ColorSpace class
David Plowman
david.plowman at raspberrypi.com
Thu Nov 18 16:19:27 CET 2021
This class represents a color space by defining its color primaries,
YCbCr encoding, the transfer (gamma) function it uses, and whether the
output is full or limited range.
Signed-off-by: David Plowman <david.plowman at raspberrypi.com>
Reviewed-by: Naushir Patuck <naush at raspberrypi.com>
---
include/libcamera/color_space.h | 79 +++++++++++
include/libcamera/meson.build | 1 +
src/libcamera/color_space.cpp | 243 ++++++++++++++++++++++++++++++++
src/libcamera/meson.build | 1 +
4 files changed, 324 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..44ac077a
--- /dev/null
+++ b/include/libcamera/color_space.h
@@ -0,0 +1,79 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/*
+ * Copyright (C) 2021, Raspberry Pi (Trading) Limited
+ *
+ * color_space.h - color space definitions
+ */
+
+#ifndef __LIBCAMERA_COLOR_SPACE_H__
+#define __LIBCAMERA_COLOR_SPACE_H__
+
+#include <optional>
+#include <string>
+
+namespace libcamera {
+
+class ColorSpace
+{
+public:
+ enum class Primaries : int {
+ Raw,
+ Smpte170m,
+ Rec709,
+ Rec2020,
+ };
+
+ enum class YcbcrEncoding : int {
+ Rec601,
+ Rec709,
+ Rec2020,
+ };
+
+ enum class TransferFunction : int {
+ Linear,
+ Srgb,
+ Rec709,
+ };
+
+ enum class Range : int {
+ Full,
+ Limited,
+ };
+
+ constexpr ColorSpace(Primaries p, YcbcrEncoding e, TransferFunction t, Range r)
+ : primaries(p), ycbcrEncoding(e), transferFunction(t), 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;
+ YcbcrEncoding ycbcrEncoding;
+ TransferFunction transferFunction;
+ Range range;
+
+ const std::string toString() const;
+ static const std::string toString(const std::optional<ColorSpace> &colorSpace);
+};
+
+constexpr ColorSpace ColorSpace::Raw = { Primaries::Raw, YcbcrEncoding::Rec601, TransferFunction::Linear, Range::Full };
+constexpr ColorSpace ColorSpace::Jpeg = { Primaries::Rec709, YcbcrEncoding::Rec601, TransferFunction::Srgb, Range::Full };
+constexpr ColorSpace ColorSpace::Srgb = { Primaries::Rec709, YcbcrEncoding::Rec601, TransferFunction::Srgb, Range::Limited };
+constexpr ColorSpace ColorSpace::Smpte170m = { Primaries::Smpte170m, YcbcrEncoding::Rec601, TransferFunction::Rec709, Range::Limited };
+constexpr ColorSpace ColorSpace::Rec709 = { Primaries::Rec709, YcbcrEncoding::Rec709, TransferFunction::Rec709, Range::Limited };
+constexpr ColorSpace ColorSpace::Rec2020 = { Primaries::Rec2020, YcbcrEncoding::Rec2020, TransferFunction::Rec709, Range::Limited };
+
+bool operator==(const ColorSpace &lhs, const ColorSpace &rhs);
+static inline bool operator!=(const ColorSpace &lhs, const ColorSpace &rhs)
+{
+ return !(lhs == rhs);
+}
+
+} /* namespace libcamera */
+
+#endif /* __LIBCAMERA_COLOR_SPACE_H__ */
diff --git a/include/libcamera/meson.build b/include/libcamera/meson.build
index 7155ff20..131e1740 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',
'compiler.h',
'controls.h',
'file_descriptor.h',
diff --git a/src/libcamera/color_space.cpp b/src/libcamera/color_space.cpp
new file mode 100644
index 00000000..1a5fc7a2
--- /dev/null
+++ b/src/libcamera/color_space.cpp
@@ -0,0 +1,243 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/*
+ * Copyright (C) 2021, Raspberry Pi (Trading) Limited
+ *
+ * color_space.cpp - color spaces.
+ */
+
+#include <libcamera/color_space.h>
+
+#include <algorithm>
+#include <sstream>
+#include <vector>
+
+/**
+ * \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 Y'CbCr encoding,
+ * the transfer function 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:
+ *
+ * <a href="https://www.kernel.org/doc/html/v5.10/userspace-api/media/v4l/colorspaces-details.html#col-srgb">sRGB</a>
+ * <a href="https://www.kernel.org/doc/html/v5.10/userspace-api/media/v4l/colorspaces-details.html#col-jpeg">JPEG</a>
+ * <a href="https://www.kernel.org/doc/html/v5.10/userspace-api/media/v4l/colorspaces-details.html#col-smpte-170m">SMPTE 170M</a>
+ * <a href="https://www.kernel.org/doc/html/v5.10/userspace-api/media/v4l/colorspaces-details.html#col-rec709">Rec.709</a>
+ * <a href="https://www.kernel.org/doc/html/v5.10/userspace-api/media/v4l/colorspaces-details.html#col-bt2020">Rec.2020</a>
+ */
+
+/**
+ * \enum ColorSpace::Primaries
+ * \brief The color primaries for this color space
+ *
+ * \var ColorSpace::Primaries::Raw
+ * \brief These are raw colors directly from a sensor
+ * \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::YcbcrEncoding
+ * \brief The Y'CbCr encoding
+ *
+ * \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::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::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, Encoding e, TransferFunction t, Range r)
+ * \brief Construct a ColorSpace from explicit values
+ * \param[in] p The color primaries
+ * \param[in] e The Y'CbCr encoding
+ * \param[in] t The transfer function for the color space
+ * \param[in] r The range of the pixel values in this color space
+ */
+
+/**
+ * \brief Assemble and return a readable string representation of the
+ * ColorSpace
+ * \return A string describing the ColorSpace
+ */
+const std::string ColorSpace::toString() const
+{
+ /* Print out a brief name only for standard color sapces. */
+
+ static const std::vector<std::pair<ColorSpace, const char *>> 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);
+
+ static const char *primariesNames[] = {
+ "Raw",
+ "Smpte170m",
+ "Rec709",
+ "Rec2020",
+ };
+ static const char *encodingNames[] = {
+ "Rec601",
+ "Rec709",
+ "Rec2020",
+ };
+ static const char *transferFunctionNames[] = {
+ "Linear",
+ "Srgb",
+ "Rec709",
+ };
+ static const char *rangeNames[] = {
+ "Full",
+ "Limited",
+ };
+
+ std::stringstream ss;
+ ss << std::string(primariesNames[static_cast<int>(primaries)]) << "/"
+ << std::string(encodingNames[static_cast<int>(ycbcrEncoding)]) << "/"
+ << std::string(transferFunctionNames[static_cast<int>(transferFunction)]) << "/"
+ << std::string(rangeNames[static_cast<int>(range)]);
+
+ return ss.str();
+}
+
+/**
+ * \brief Assemble and return a readable string representation of an
+ * optional ColorSpace
+ * \return A string describing the optional ColorSpace
+ */
+const std::string ColorSpace::toString(const std::optional<ColorSpace> &colorSpace)
+{
+ if (!colorSpace)
+ return "Unknown";
+
+ return colorSpace->toString();
+}
+
+/**
+ * \var ColorSpace::primaries
+ * \brief The color primaries
+ */
+
+/**
+ * \var ColorSpace::ycbcrEncoding
+ * \brief The Y'CbCr encoding
+ */
+
+/**
+ * \var ColorSpace::transferFunction
+ * \brief The transfer function for this color space
+ */
+
+/**
+ * \var ColorSpace::range
+ * \brief The pixel range used by this color space
+ */
+
+/**
+ * \var ColorSpace::Undefined
+ * \brief A constant representing a fully undefined color space
+ */
+
+/**
+ * \var ColorSpace::Raw
+ * \brief A constant representing a raw color space (from a sensor)
+ */
+
+/**
+ * \var ColorSpace::Jpeg
+ * \brief A constant representing the JPEG color space used for
+ * encoding JPEG images (and regarded as being the same as the sRGB
+ * color space)
+ */
+
+/**
+ * \var ColorSpace::Smpte170m
+ * \brief A constant representing the SMPTE170M color space
+ */
+
+/**
+ * \var ColorSpace::Rec709
+ * \brief A constant representing the Rec.709 color space
+ */
+
+/**
+ * \var ColorSpace::Rec2020
+ * \brief A constant representing the Rec.2020 color space
+ */
+
+/**
+ * \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.ycbcrEncoding == rhs.ycbcrEncoding &&
+ lhs.transferFunction == rhs.transferFunction &&
+ 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 6727a777..e7371d20 100644
--- a/src/libcamera/meson.build
+++ b/src/libcamera/meson.build
@@ -8,6 +8,7 @@ libcamera_sources = files([
'camera_manager.cpp',
'camera_sensor.cpp',
'camera_sensor_properties.cpp',
+ 'color_space.cpp',
'controls.cpp',
'control_serializer.cpp',
'control_validator.cpp',
--
2.20.1
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