[libcamera-devel] [PATCH 3/6] libcamera: color_space: Add fromString() function
Umang Jain
umang.jain at ideasonboard.com
Wed Aug 24 08:37:59 CEST 2022
Hi Laurent,
Thank you for the patch.
On 8/23/22 11:13 PM, Laurent Pinchart via libcamera-devel wrote:
> Add a ColorSpace:fromString() function to parse a string into a color
> space. The string can either contain the name of a well-known color
> space, or four color space components separate by a '/' character.
I don't see the order of four components separated by '/' - documented
in the codebase.
Should we document the string order as well?
'''
The string representation of the colorspace separated by '/' is as follows:
<Color primaries>/<Transfer function>/<Y'CbCr Encoding>/<Range>
'''
>
> Signed-off-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
Reviewed-by: Umang Jain <umang.jain at ideasonboard.com>
> ---
> include/libcamera/color_space.h | 2 +
> src/libcamera/color_space.cpp | 149 +++++++++++++++++++++++++-------
> 2 files changed, 121 insertions(+), 30 deletions(-)
>
> diff --git a/include/libcamera/color_space.h b/include/libcamera/color_space.h
> index 8030a264c66f..f493f72d2db8 100644
> --- a/include/libcamera/color_space.h
> +++ b/include/libcamera/color_space.h
> @@ -59,6 +59,8 @@ public:
>
> std::string toString() const;
> static std::string toString(const std::optional<ColorSpace> &colorSpace);
> +
> + static std::optional<ColorSpace> fromString(const std::string &str);
> };
>
> bool operator==(const ColorSpace &lhs, const ColorSpace &rhs);
> diff --git a/src/libcamera/color_space.cpp b/src/libcamera/color_space.cpp
> index 1b2dd2404452..5233626f5ae9 100644
> --- a/src/libcamera/color_space.cpp
> +++ b/src/libcamera/color_space.cpp
> @@ -12,6 +12,9 @@
> #include <map>
> #include <sstream>
> #include <utility>
> +#include <vector>
> +
> +#include <libcamera/base/utils.h>
>
> /**
> * \file color_space.h
> @@ -208,6 +211,44 @@ const ColorSpace ColorSpace::Rec2020 = {
> * \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
> @@ -223,14 +264,6 @@ 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::Srgb, "sRGB" },
> - { ColorSpace::Sycc, "sYCC" },
> - { 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;
> @@ -240,28 +273,6 @@ 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;
> @@ -303,6 +314,84 @@ std::string ColorSpace::toString(const std::optional<ColorSpace> &colorSpace)
> return colorSpace->toString();
> }
>
> +/**
> + * \brief Construct a color space from a string
> + * \param[in] str The string
> + *
> + * The string \a str can contain the name of a well-known color space, or be
> + * made of the four color space components separate by a '/' character. 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
> + */
> +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 Compare color spaces for equality
> * \return True if the two color spaces are identical, false otherwise
More information about the libcamera-devel
mailing list