[libcamera-devel] [PATCH 3/6] libcamera: color_space: Add fromString() function
Laurent Pinchart
laurent.pinchart at ideasonboard.com
Thu Aug 25 16:36:54 CEST 2022
Hi Umang,
On Thu, Aug 25, 2022 at 06:49:53PM +0530, Umang Jain wrote:
> On 8/25/22 3:02 AM, Laurent Pinchart wrote:
> > On Wed, Aug 24, 2022 at 12:40:59PM +0300, Laurent Pinchart via libcamera-devel wrote:
> >> On Wed, Aug 24, 2022 at 12:07:59PM +0530, Umang Jain wrote:
> >>> 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>
> >>> '''
> >>
> >> I'll expand the documentation of the function to make this more
> >> explicit.
>
> Thank you!
>
> >> I'm also wondering (warning, bikeshedding ahead) if the '/'-separated
> >> format is the best option. GStreamer uses colons to separate the
> >> components, and only accepts numerical values for the components in that
> >> case. I'm not aware of (but haven't looked for) alternatives.
>
> Oh, so we can't really align with gstreamer using the colon(':') because
> it would split awkwardly with utils::split(str, ":") I think
>
> ColorSpace::Primaries::Rec709:ColorSpace::TransferFunction::Rec709:ColorSpace::YcbcrEncoding::Rec709:ColorSpace::Range::Full
The string doesn't have to fully qualify the components, it would be
Rec709:Rec709:Rec709:Full
> In that case, I think "/" is our best choice. Second best I think will
> be "|"
>
> I saw a few Colorspace::toString() randomly on the internet, but none
> were structural. They were mostly just meant to print it out for logs
> (and not treating as string input).
>
> I also saw DRM also has colorspaces but haven't came across a helper
> like we need. I am not sure if it's worth to look further! "/" is
> already a good starting point, given our requirements.
>
> > By the way, the '/'-separated format comes from toString(). If we want
> > to change it, we should update the toString() function as well.
>
> Ack.
>
> >>>> 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
--
Regards,
Laurent Pinchart
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