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
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
|
/*
* Copyright 2016 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#include "Resources.h"
#include "SkBitmap.h"
#include "SkCanvas.h"
#include "SkCodec.h"
#include "SkColorSpace.h"
#include "SkCommandLineFlags.h"
#include "SkForceLinking.h"
#include "SkImageEncoder.h"
#include "SkMatrix44.h"
#include "SkOSFile.h"
__SK_FORCE_IMAGE_DECODER_LINKING;
DEFINE_string2(input, i, "input.png", "A path to the input image.");
DEFINE_string2(output, o, "output.png", "A path to the output image.");
/**
* Loads the triangular gamut as a set of three points.
*/
static void load_gamut(SkPoint rgb[], const SkMatrix44& xyz) {
// rx = rX / (rX + rY + rZ)
// ry = rX / (rX + rY + rZ)
// gx, gy, bx, and gy are calulcated similarly.
float rSum = xyz.get(0, 0) + xyz.get(0, 1) + xyz.get(0, 2);
float gSum = xyz.get(1, 0) + xyz.get(1, 1) + xyz.get(1, 2);
float bSum = xyz.get(2, 0) + xyz.get(2, 1) + xyz.get(2, 2);
rgb[0].fX = xyz.get(0, 0) / rSum;
rgb[0].fY = xyz.get(0, 1) / rSum;
rgb[1].fX = xyz.get(1, 0) / gSum;
rgb[1].fY = xyz.get(1, 1) / gSum;
rgb[2].fX = xyz.get(2, 0) / bSum;
rgb[2].fY = xyz.get(2, 1) / bSum;
}
/**
* Calculates the area of the triangular gamut.
*/
float calculate_area(SkPoint abc[]) {
SkPoint a = abc[0];
SkPoint b = abc[1];
SkPoint c = abc[2];
return 0.5f * SkTAbs(a.fX*b.fY + b.fX*c.fY - a.fX*c.fY - c.fX*b.fY - b.fX*a.fY);
}
int main(int argc, char** argv) {
SkCommandLineFlags::SetUsage(
"Usage: visualize_color_gamut --input <path to input image>"
"--output <path to output image>\n"
"Description: Writes a visualization of the color gamut to the output image\n");
SkCommandLineFlags::Parse(argc, argv);
const char* input = FLAGS_input[0];
const char* output = FLAGS_output[0];
if (!input || !output) {
SkCommandLineFlags::PrintUsage();
return -1;
}
SkAutoTUnref<SkData> data(SkData::NewFromFileName(input));
if (!data) {
SkDebugf("Cannot find input image.\n");
return -1;
}
SkAutoTDelete<SkCodec> codec(SkCodec::NewFromData(data));
if (!codec) {
SkDebugf("Invalid input image.\n");
return -1;
}
// Load a graph of the CIE XYZ color gamut.
SkBitmap bitmap;
if (!GetResourceAsBitmap("gamut.png", &bitmap)) {
SkDebugf("Program failure.\n");
return -1;
}
SkCanvas canvas(bitmap);
sk_sp<SkColorSpace> colorSpace = sk_ref_sp(codec->getColorSpace());
if (!colorSpace) {
SkDebugf("Image had no embedded color space information. Defaulting to sRGB.\n");
colorSpace = SkColorSpace::NewNamed(SkColorSpace::kSRGB_Named);
}
// Calculate the points in the gamut from the XYZ values.
SkMatrix44 xyz = colorSpace->xyz();
SkPoint rgb[4];
load_gamut(rgb, xyz);
// Report the XYZ values.
SkDebugf(" X Y Z\n");
SkDebugf("Red %.2f %.2f %.2f\n", xyz.get(0, 0), xyz.get(0, 1), xyz.get(0, 2));
SkDebugf("Green %.2f %.2f %.2f\n", xyz.get(1, 0), xyz.get(1, 1), xyz.get(1, 2));
SkDebugf("Blue %.2f %.2f %.2f\n", xyz.get(2, 0), xyz.get(2, 1), xyz.get(2, 2));
// Report the area of the gamut.
SkDebugf("Area of Gamut: %g\n", calculate_area(rgb));
// Now transform the points so they can be drawn on our canvas. We use 1000 pixels
// to represent the space from 0 to 1. Note that the graph is at an offset of (50, 50).
// Also note that y increases as we move down the canvas.
rgb[0].fX = 50 + 1000*rgb[0].fX;
rgb[0].fY = 50 + 1000*(1 - rgb[0].fY);
rgb[1].fX = 50 + 1000*rgb[1].fX;
rgb[1].fY = 50 + 1000*(1 - rgb[1].fY);
rgb[2].fX = 50 + 1000*rgb[2].fX;
rgb[2].fY = 50 + 1000*(1 - rgb[2].fY);
// Repeat the first point to connect the polygon.
rgb[3] = rgb[0];
SkPaint paint;
canvas.drawPoints(SkCanvas::kPolygon_PointMode, 4, rgb, paint);
// Finally, encode the result to out.png.
SkAutoTUnref<SkData> out(SkImageEncoder::EncodeData(bitmap, SkImageEncoder::kPNG_Type, 100));
if (!out) {
SkDebugf("Failed to encode output.\n");
return -1;
}
SkFILEWStream stream(output);
bool result = stream.write(out->data(), out->size());
if (!result) {
SkDebugf("Failed to write output.\n");
return -1;
}
return 0;
}
|
