Method bake

src/OpenColorIO/fileformats/FileFormatCTF.cpp:1349–1553

This baker is based on what was done for ResolveCube and HDL. We enhanced it to use a half-domain Lut1D for the shaper to better represent transforms expecting linear inputs. TODO: The CLF format is more powerful than those older formats and there is no need to be limited to a Lut1D + Lut3D structure -- more ops could be used when necessary for a more accurate bake.

// no need to be limited to a Lut1D + Lut3D structure -- more ops could be used
// when necessary for a more accurate bake.
void LocalFileFormat::bake(const Baker & baker,
                           const std::string & formatName,
                           std::ostream & ostream) const
{
    static constexpr int DEFAULT_1D_SIZE = 4096;
    static constexpr int DEFAULT_3D_SIZE = 64;

    // NB: By default, the shaper uses a half-domain LUT1D, which is always 65536 entries.
    // If the user requests some other size, a typical (non-half-domain) LUT1D will be used.
    if (formatName != FILEFORMAT_CTF && formatName != FILEFORMAT_CLF)
    {
        std::ostringstream os;
        os << "Unknown CLF/CTF file format name, '";
        os << formatName << "'.";
        throw Exception(os.str().c_str());
    }

    //
    // Initialize config and data.
    //

    ConstConfigRcPtr config = baker.getConfig();

    int onedSize = baker.getCubeSize();
    if (onedSize == -1)
    {
        onedSize = DEFAULT_1D_SIZE;
    }

    int cubeSize = baker.getCubeSize();
    if (cubeSize == -1)
    {
        cubeSize = DEFAULT_3D_SIZE;
    }
    cubeSize = std::max(2, cubeSize); // smallest cube is 2x2x2

    // Get spaces from baker.
    const std::string shaperSpace = baker.getShaperSpace();

    //
    // Determine required LUT type.
    //

    constexpr int CTF_1D = 1;    // 1D LUT version number
    constexpr int CTF_3D = 2;    // 3D LUT version number
    constexpr int CTF_1D_3D = 3; // 3D LUT with 1D prelut

    int required_lut = -1;

    ConstCPUProcessorRcPtr inputToTarget = GetInputToTargetProcessor(baker);

    if (inputToTarget->hasChannelCrosstalk())
    {
        if (shaperSpace.empty())
        {
            // Has crosstalk, but no shaper, so need 3D LUT.
            required_lut = CTF_3D;
        }