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// Copyright (c) the JPEG XL Project Authors. All rights reserved.
//
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
#include "lib/extras/hlg.h"
#include <jxl/cms.h>
#include <cmath>
namespace jxl {
float GetHlgGamma(const float peak_luminance, const float surround_luminance) {
return 1.2f * std::pow(1.111f, std::log2(peak_luminance / 1000.f)) *
std::pow(0.98f, std::log2(surround_luminance / 5.f));
}
Status HlgOOTF(ImageBundle* ib, const float gamma, ThreadPool* pool) {
ColorEncoding linear_rec2020;
linear_rec2020.SetColorSpace(ColorSpace::kRGB);
JXL_RETURN_IF_ERROR(linear_rec2020.SetPrimariesType(Primaries::k2100));
JXL_RETURN_IF_ERROR(linear_rec2020.SetWhitePointType(WhitePoint::kD65));
linear_rec2020.Tf().SetTransferFunction(TransferFunction::kLinear);
JXL_RETURN_IF_ERROR(linear_rec2020.CreateICC());
JXL_RETURN_IF_ERROR(
ib->TransformTo(linear_rec2020, *JxlGetDefaultCms(), pool));
const auto process_row = [&](const int y, const int thread) -> Status {
float* const JXL_RESTRICT rows[3] = {ib->color()->PlaneRow(0, y),
ib->color()->PlaneRow(1, y),
ib->color()->PlaneRow(2, y)};
for (size_t x = 0; x < ib->xsize(); ++x) {
float& red = rows[0][x];
float& green = rows[1][x];
float& blue = rows[2][x];
const float luminance = 0.2627f * red + 0.6780f * green + 0.0593f * blue;
const float ratio = std::pow(luminance, gamma - 1);
if (std::isfinite(ratio)) {
red *= ratio;
green *= ratio;
blue *= ratio;
}
}
return true;
};
JXL_RETURN_IF_ERROR(RunOnPool(pool, 0, ib->ysize(), ThreadPool::NoInit,
process_row, "HlgOOTF"));
return true;
}
Status HlgInverseOOTF(ImageBundle* ib, const float gamma, ThreadPool* pool) {
return HlgOOTF(ib, 1.f / gamma, pool);
}
} // namespace jxl