Method isColorSpaceLinear

src/OpenColorIO/Config.cpp:2784–2906

///////////////////////////////////////////////////////////////////////////

bool Config::isColorSpaceLinear(const char * colorSpace, ReferenceSpaceType referenceSpaceType) const
{
    auto cs = getColorSpace(colorSpace);

    if (cs == nullptr)
    {
        std::ostringstream os;
        os << "Could not test colorspace linearity. Colorspace " << colorSpace << " does not exist.";
        throw Exception(os.str().c_str()); 
    }

    if (cs->isData())
    {
        return false;
    }

    // Colorspace is not linear if the types are opposite.
    if (cs->getReferenceSpaceType() != referenceSpaceType)
    {
        return false;
    }

    std::string encoding = cs->getEncoding();
    if (!encoding.empty())
    {
        // Check the encoding value if it is set.        
        if ((StringUtils::Compare(cs->getEncoding(), "scene-linear") && 
            referenceSpaceType == REFERENCE_SPACE_SCENE) || 
            (StringUtils::Compare(cs->getEncoding(), "display-linear") && 
            referenceSpaceType == REFERENCE_SPACE_DISPLAY))
        {
            return true;
        }
        else
        {
            return false;
        }
    }

    // We want to assess linearity over at least a reasonable range of values, so use a very dark 
    // value and a very bright value. Test neutral, red, green, and blue points to detect situations 
    // where the neutral may be linear but there is non-linearity off the neutral axis.
    auto evaluate = [](const Config & config, ConstTransformRcPtr &t) -> bool
    {
        std::vector<float> img = 
        { 
            0.0625f, 0.0625f, 0.0625f, 4.f, 4.f, 4.f,
            0.0625f, 0.f, 0.f, 4.f, 0.f, 0.f,
            0.f, 0.0625f, 0.f, 0.f, 4.f, 0.f,
            0.f, 0.f, 0.0625f, 0.f, 0.f, 4.f
        };
        std::vector<float> dst(img.size(), 0.f);

        PackedImageDesc desc(&img[0], 8, 1, CHANNEL_ORDERING_RGB);
        PackedImageDesc descDst(&dst[0], 8, 1, CHANNEL_ORDERING_RGB);

        auto procToReference = config.getImpl()->getProcessorWithoutCaching(
            config, t, TRANSFORM_DIR_FORWARD