[libcamera-devel] [PATCH 3/6] libcamera: color_space: Add fromString() function
Laurent Pinchart
laurent.pinchart at ideasonboard.com
Thu Aug 25 17:51:57 CEST 2022
On Thu, Aug 25, 2022 at 09:13:02PM +0530, Umang Jain wrote:
> On 8/25/22 8:06 PM, Laurent Pinchart wrote:
> > 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
>
> Yes correct, it can be - Can we keep ":" as the splitter then? ;-)
Should I then update toString() too ?
David, any opinion ?
> >> 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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