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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.
#if defined(LIB_JXL_DEC_TONE_MAPPING_INL_H_) == defined(HWY_TARGET_TOGGLE)
#ifdef LIB_JXL_DEC_TONE_MAPPING_INL_H_
#undef LIB_JXL_DEC_TONE_MAPPING_INL_H_
#else
#define LIB_JXL_DEC_TONE_MAPPING_INL_H_
#endif
#include <hwy/highway.h>
#include "lib/jxl/transfer_functions-inl.h"
HWY_BEFORE_NAMESPACE();
namespace jxl {
namespace HWY_NAMESPACE {
namespace {
// These templates are not found via ADL.
using hwy::HWY_NAMESPACE::Clamp;
using hwy::HWY_NAMESPACE::Max;
using hwy::HWY_NAMESPACE::ZeroIfNegative;
template <typename D>
class Rec2408ToneMapper {
private:
using V = hwy::HWY_NAMESPACE::Vec<D>;
public:
explicit Rec2408ToneMapper(std::pair<float, float> source_range,
std::pair<float, float> target_range,
const float primaries_luminances[3])
: source_range_(source_range),
target_range_(target_range),
red_Y_(primaries_luminances[0]),
green_Y_(primaries_luminances[1]),
blue_Y_(primaries_luminances[2]) {}
void ToneMap(V* red, V* green, V* blue) const {
const V luminance = Mul(Set(df_, source_range_.second),
(MulAdd(Set(df_, red_Y_), *red,
MulAdd(Set(df_, green_Y_), *green,
Mul(Set(df_, blue_Y_), *blue)))));
const V pq_mastering_min = Set(df_, pq_mastering_min_);
const V inv_pq_mastering_range = Set(df_, inv_pq_mastering_range_);
const V normalized_pq = Min(
Set(df_, 1.f),
Mul(Sub(InvEOTF(luminance), pq_mastering_min), inv_pq_mastering_range));
const V ks = Set(df_, ks_);
const V e2 =
IfThenElse(Lt(normalized_pq, ks), normalized_pq, P(normalized_pq));
const V one_minus_e2 = Sub(Set(df_, 1), e2);
const V one_minus_e2_2 = Mul(one_minus_e2, one_minus_e2);
const V one_minus_e2_4 = Mul(one_minus_e2_2, one_minus_e2_2);
const V b = Set(df_, min_lum_);
const V e3 = MulAdd(b, one_minus_e2_4, e2);
const V pq_mastering_range = Set(df_, pq_mastering_range_);
const V e4 = MulAdd(e3, pq_mastering_range, pq_mastering_min);
const V new_luminance =
Min(Set(df_, target_range_.second),
ZeroIfNegative(
Mul(Set(df_, 10000), TF_PQ().DisplayFromEncoded(df_, e4))));
const V ratio = Div(new_luminance, luminance);
const V inv_target_peak = Set(df_, inv_target_peak_);
const V normalizer = Set(df_, normalizer_);
const V multiplier = Mul(ratio, normalizer);
for (V* const val : {red, green, blue}) {
*val = IfThenElse(Le(luminance, Set(df_, 1e-6f)),
Mul(new_luminance, inv_target_peak),
Mul(*val, multiplier));
}
}
private:
V InvEOTF(const V luminance) const {
return TF_PQ().EncodedFromDisplay(df_,
Mul(luminance, Set(df_, 1. / 10000)));
}
float InvEOTF(const float luminance) const {
return TF_PQ().EncodedFromDisplay(luminance / 10000.0f);
}
V T(const V a) const {
const V ks = Set(df_, ks_);
const V inv_one_minus_ks = Set(df_, inv_one_minus_ks_);
return Mul(Sub(a, ks), inv_one_minus_ks);
}
V P(const V b) const {
const V t_b = T(b);
const V t_b_2 = Mul(t_b, t_b);
const V t_b_3 = Mul(t_b_2, t_b);
const V ks = Set(df_, ks_);
const V max_lum = Set(df_, max_lum_);
return MulAdd(
MulAdd(Set(df_, 2), t_b_3, MulAdd(Set(df_, -3), t_b_2, Set(df_, 1))),
ks,
MulAdd(Add(t_b_3, MulAdd(Set(df_, -2), t_b_2, t_b)),
Sub(Set(df_, 1), ks),
Mul(MulAdd(Set(df_, -2), t_b_3, Mul(Set(df_, 3), t_b_2)),
max_lum)));
}
D df_;
const std::pair<float, float> source_range_;
const std::pair<float, float> target_range_;
const float red_Y_;
const float green_Y_;
const float blue_Y_;
const float pq_mastering_min_ = InvEOTF(source_range_.first);
const float pq_mastering_max_ = InvEOTF(source_range_.second);
const float pq_mastering_range_ = pq_mastering_max_ - pq_mastering_min_;
const float inv_pq_mastering_range_ = 1.0f / pq_mastering_range_;
// TODO(eustas): divide instead of inverse-multiply?
const float min_lum_ = (InvEOTF(target_range_.first) - pq_mastering_min_) *
inv_pq_mastering_range_;
// TODO(eustas): divide instead of inverse-multiply?
const float max_lum_ = (InvEOTF(target_range_.second) - pq_mastering_min_) *
inv_pq_mastering_range_;
const float ks_ = 1.5f * max_lum_ - 0.5f;
const float b_ = min_lum_;
const float inv_one_minus_ks_ = 1.0f / std::max(1e-6f, 1.0f - ks_);
const float normalizer_ = source_range_.second / target_range_.second;
const float inv_target_peak_ = 1.f / target_range_.second;
};
class HlgOOTF {
public:
explicit HlgOOTF(float source_luminance, float target_luminance,
const float primaries_luminances[3])
: HlgOOTF(/*gamma=*/std::pow(
1.111f, std::log2(target_luminance / source_luminance)),
primaries_luminances) {}
static HlgOOTF FromSceneLight(float display_luminance,
const float primaries_luminances[3]) {
return HlgOOTF(/*gamma=*/1.2f *
std::pow(1.111f, std::log2(display_luminance / 1000.f)),
primaries_luminances);
}
static HlgOOTF ToSceneLight(float display_luminance,
const float primaries_luminances[3]) {
return HlgOOTF(
/*gamma=*/(1 / 1.2f) *
std::pow(1.111f, -std::log2(display_luminance / 1000.f)),
primaries_luminances);
}
template <typename V>
void Apply(V* red, V* green, V* blue) const {
hwy::HWY_NAMESPACE::DFromV<V> df;
if (!apply_ootf_) return;
const V luminance =
MulAdd(Set(df, red_Y_), *red,
MulAdd(Set(df, green_Y_), *green, Mul(Set(df, blue_Y_), *blue)));
const V ratio =
Min(FastPowf(df, luminance, Set(df, exponent_)), Set(df, 1e9));
*red = Mul(*red, ratio);
*green = Mul(*green, ratio);
*blue = Mul(*blue, ratio);
}
bool WarrantsGamutMapping() const { return apply_ootf_ && exponent_ < 0; }
private:
explicit HlgOOTF(float gamma, const float luminances[3])
: exponent_(gamma - 1),
red_Y_(luminances[0]),
green_Y_(luminances[1]),
blue_Y_(luminances[2]) {}
const float exponent_;
const bool apply_ootf_ = exponent_ < -0.01f || 0.01f < exponent_;
const float red_Y_;
const float green_Y_;
const float blue_Y_;
};
template <typename V>
void GamutMap(V* red, V* green, V* blue, const float primaries_luminances[3],
float preserve_saturation = 0.1f) {
hwy::HWY_NAMESPACE::DFromV<V> df;
const V luminance =
MulAdd(Set(df, primaries_luminances[0]), *red,
MulAdd(Set(df, primaries_luminances[1]), *green,
Mul(Set(df, primaries_luminances[2]), *blue)));
// Desaturate out-of-gamut pixels. This is done by mixing each pixel
// with just enough gray of the target luminance to make all
// components non-negative.
// - For saturation preservation, if a component is still larger than
// 1 then the pixel is normalized to have a maximum component of 1.
// That will reduce its luminance.
// - For luminance preservation, getting all components below 1 is
// done by mixing in yet more gray. That will desaturate it further.
V gray_mix_saturation = Zero(df);
V gray_mix_luminance = Zero(df);
for (const V* ch : {red, green, blue}) {
const V& val = *ch;
const V inv_val_minus_gray = Div(Set(df, 1), (Sub(val, luminance)));
gray_mix_saturation =
IfThenElse(Ge(val, luminance), gray_mix_saturation,
Max(gray_mix_saturation, Mul(val, inv_val_minus_gray)));
gray_mix_luminance =
Max(gray_mix_luminance,
IfThenElse(Le(val, luminance), gray_mix_saturation,
Mul(Sub(val, Set(df, 1)), inv_val_minus_gray)));
}
const V gray_mix = Clamp(
MulAdd(Set(df, preserve_saturation),
Sub(gray_mix_saturation, gray_mix_luminance), gray_mix_luminance),
Zero(df), Set(df, 1));
for (V* const val : {red, green, blue}) {
*val = MulAdd(gray_mix, Sub(luminance, *val), *val);
}
const V normalizer =
Div(Set(df, 1), Max(Set(df, 1), Max(*red, Max(*green, *blue))));
for (V* const val : {red, green, blue}) {
*val = Mul(*val, normalizer);
}
}
} // namespace
// NOLINTNEXTLINE(google-readability-namespace-comments)
} // namespace HWY_NAMESPACE
} // namespace jxl
HWY_AFTER_NAMESPACE();
#endif // LIB_JXL_DEC_TONE_MAPPING_INL_H_
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