1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
|
// 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 <cmath>
#include "lib/jxl/enc_color_management.h"
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);
linear_rec2020.primaries = Primaries::k2100;
linear_rec2020.white_point = WhitePoint::kD65;
linear_rec2020.tf.SetTransferFunction(TransferFunction::kLinear);
JXL_RETURN_IF_ERROR(linear_rec2020.CreateICC());
JXL_RETURN_IF_ERROR(ib->TransformTo(linear_rec2020, GetJxlCms(), pool));
JXL_RETURN_IF_ERROR(RunOnPool(
pool, 0, ib->ysize(), ThreadPool::NoInit,
[&](const int y, const int thread) {
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;
}
}
},
"HlgOOTF"));
return true;
}
Status HlgInverseOOTF(ImageBundle* ib, const float gamma, ThreadPool* pool) {
return HlgOOTF(ib, 1.f / gamma, pool);
}
} // namespace jxl
|
