[libcamera-devel] [PATCH 3/6] libcamera: color_space: Add fromString() function
Umang Jain
umang.jain at ideasonboard.com
Thu Aug 25 17:43:02 CEST 2022
On 8/25/22 8:06 PM, Laurent Pinchart wrote:
> 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
Yes correct, it can be - Can we keep ":" as the splitter then? ;-)
>
>> 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
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