Function TestLog

tests/cpu/ops/log/LogOpCPU_tests.cpp:15–99

constexpr float inf = std::numeric_limits<float>::infinity();

void TestLog(float logBase)
{
    const float rgbaImage[32] = { 0.0367126f, 0.5f, 1.f,     0.f,
                                  0.2f,       0.f,   .99f, 128.f,
                                  qnan,       qnan, qnan,    0.f,
                                  0.f,        0.f,  0.f,     qnan,
                                  inf,        inf,  inf,     0.f,
                                  0.f,        0.f,  0.f,     inf,
                                 -inf,       -inf, -inf,     0.f,
                                  0.f,        0.f,  0.f,    -inf };
                                  
    float rgba[32] = {};

    OCIO::ConstLogOpDataRcPtr logOp = std::make_shared<OCIO::LogOpData>(
        logBase, OCIO::TRANSFORM_DIR_FORWARD);

    OCIO::ConstOpCPURcPtr pRenderer = OCIO::GetLogRenderer(logOp, true);
    pRenderer->apply(rgbaImage, rgba, 8);

    const float minValue = std::numeric_limits<float>::min();

    // LogOpCPU implementation uses optimized logarithm approximation
    // cannot use strict comparison.
#if OCIO_USE_SSE2
    const float error = 5e-5f;
#else
    const float error = 1e-5f;
#endif // OCIO_USE_SSE2

    for (unsigned i = 0; i < 8; ++i)
    {
        const bool isAlpha = (i % 4 == 3);

        const float result = rgba[i];
        float expected = rgbaImage[i];
        if (!isAlpha)
        {
            expected = logf(std::max(minValue, (float)expected)) / logf(logBase);
        }

        // Evaluating output for input rgbaImage[0-7] = { 0.0367126f, 0.5f, 1.f,     0.f,
        //                                                0.2f,       0.f,   .99f, 128.f,
        //                                                ... }
        OCIO_CHECK_CLOSE(result, expected, error);
    }

    const float resMin = logf(minValue) / logf(logBase);

    // Evaluating output for input rgbaImage[8-11] = {qnan, qnan, qnan, 0.}.
    OCIO_CHECK_CLOSE(rgba[8], resMin, error);
    OCIO_CHECK_EQUAL(rgba[11], 0.0f);

    // Evaluating output for input rgbaImage[12-15] = {0., 0., 0., qnan.}.
    OCIO_CHECK_CLOSE(rgba[12], resMin, error);
    OCIO_CHECK_ASSERT(OCIO::IsNan(rgba[15]));

    // SSE implementation of sseLog2 & sseExp2 do not behave like CPU.
    // TODO: Address issues with Inf/NaN handling demonstrated by many of the test results below.