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