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/*
* 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_Base.h"
#include "SkCommandLineFlags.h"
#include "SkForceLinking.h"
#include "SkImageEncoder.h"
#include "SkMatrix44.h"
#include "SkOSFile.h"
__SK_FORCE_IMAGE_DECODER_LINKING;
DEFINE_string(input, "input.png", "A path to the input image.");
DEFINE_string(output, "output.png", "A path to the output image.");
DEFINE_bool(sRGB, false, "Draws the sRGB gamut.");
DEFINE_bool(adobeRGB, false, "Draws the Adobe RGB gamut.");
DEFINE_string(uncorrected, "", "A path to reencode the uncorrected input 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(1, 0) + xyz.get(2, 0);
float gSum = xyz.get(0, 1) + xyz.get(1, 1) + xyz.get(2, 1);
float bSum = xyz.get(0, 2) + xyz.get(1, 2) + xyz.get(2, 2);
rgb[0].fX = xyz.get(0, 0) / rSum;
rgb[0].fY = xyz.get(1, 0) / rSum;
rgb[1].fX = xyz.get(0, 1) / gSum;
rgb[1].fY = xyz.get(1, 1) / gSum;
rgb[2].fX = xyz.get(0, 2) / bSum;
rgb[2].fY = xyz.get(1, 2) / bSum;
}
/**
* Calculates the area of the triangular gamut.
*/
static 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);
}
static void draw_gamut(SkCanvas* canvas, const SkMatrix44& xyz, const char* name, SkColor color,
bool label) {
// Report the XYZ values.
SkDebugf("%s\n", name);
SkDebugf(" R G B\n");
SkDebugf("X %.3f %.3f %.3f\n", xyz.get(0, 0), xyz.get(0, 1), xyz.get(0, 2));
SkDebugf("Y %.3f %.3f %.3f\n", xyz.get(1, 0), xyz.get(1, 1), xyz.get(1, 2));
SkDebugf("Z %.3f %.3f %.3f\n", xyz.get(2, 0), xyz.get(2, 1), xyz.get(2, 2));
// Calculate the points in the gamut from the XYZ values.
SkPoint rgb[4];
load_gamut(rgb, xyz);
// Report the area of the gamut.
SkDebugf("Area of Gamut: %.3f\n\n", calculate_area(rgb));
// Magic constants that help us place the gamut triangles in the appropriate position
// on the canvas.
const float xScale = 2071.25f; // Num pixels from 0 to 1 in x
const float xOffset = 241.0f; // Num pixels until start of x-axis
const float yScale = 2067.78f; // Num pixels from 0 to 1 in y
const float yOffset = -144.78f; // Num pixels until start of y-axis
// (negative because y extends beyond image bounds)
// Now transform the points so they can be drawn on our canvas.
// Note that y increases as we move down the canvas.
rgb[0].fX = xOffset + xScale * rgb[0].fX;
rgb[0].fY = yOffset + yScale * (1.0f - rgb[0].fY);
rgb[1].fX = xOffset + xScale * rgb[1].fX;
rgb[1].fY = yOffset + yScale * (1.0f - rgb[1].fY);
rgb[2].fX = xOffset + xScale * rgb[2].fX;
rgb[2].fY = yOffset + yScale * (1.0f - rgb[2].fY);
// Repeat the first point to connect the polygon.
rgb[3] = rgb[0];
SkPaint paint;
paint.setColor(color);
paint.setStrokeWidth(6.0f);
paint.setTextSize(75.0f);
canvas->drawPoints(SkCanvas::kPolygon_PointMode, 4, rgb, paint);
if (label) {
canvas->drawText("R", 1, rgb[0].fX + 5.0f, rgb[0].fY + 75.0f, paint);
canvas->drawText("G", 1, rgb[1].fX + 5.0f, rgb[1].fY - 5.0f, paint);
canvas->drawText("B", 1, rgb[2].fX - 75.0f, rgb[2].fY - 5.0f, paint);
}
}
int main(int argc, char** argv) {
SkCommandLineFlags::SetUsage(
"Usage: visualize_color_gamut --input <path to input image> "
"--output <path to output image> "
"--sRGB <draw canonical sRGB gamut> "
"--adobeRGB <draw canonical Adobe RGB gamut> "
"--uncorrected <path to reencoded, uncorrected "
" input image>\n"
"Description: Writes a visualization of the color gamut to the output image ."
"Also, if a path is provided, writes uncorrected bytes to an unmarked "
"png, for comparison with the input 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;
}
sk_sp<SkData> data(SkData::MakeFromFileName(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 gamut;
if (!GetResourceAsBitmap("gamut.png", &gamut)) {
SkDebugf("Program failure.\n");
return -1;
}
SkCanvas canvas(gamut);
// Draw the sRGB gamut if requested.
if (FLAGS_sRGB) {
sk_sp<SkColorSpace> sRGBSpace = SkColorSpace::NewNamed(SkColorSpace::kSRGB_Named);
draw_gamut(&canvas, as_CSB(sRGBSpace)->toXYZD50(), "sRGB", 0xFFFF9394, false);
}
// Draw the Adobe RGB gamut if requested.
if (FLAGS_adobeRGB) {
sk_sp<SkColorSpace> adobeRGBSpace = SkColorSpace::NewNamed(SkColorSpace::kAdobeRGB_Named);
draw_gamut(&canvas, as_CSB(adobeRGBSpace)->toXYZD50(), "Adobe RGB", 0xFF31a9e1, false);
}
// Draw gamut for the input image.
sk_sp<SkColorSpace> colorSpace = sk_ref_sp(codec->getInfo().colorSpace());
if (!colorSpace) {
SkDebugf("Image had no embedded color space information. Defaulting to sRGB.\n");
colorSpace = SkColorSpace::NewNamed(SkColorSpace::kSRGB_Named);
}
draw_gamut(&canvas, as_CSB(colorSpace)->toXYZD50(), input, 0xFF000000, true);
// Finally, encode the result to the output file.
sk_sp<SkData> out(SkImageEncoder::EncodeData(gamut, SkImageEncoder::kPNG_Type, 100));
if (!out) {
SkDebugf("Failed to encode gamut output.\n");
return -1;
}
SkFILEWStream stream(output);
bool result = stream.write(out->data(), out->size());
if (!result) {
SkDebugf("Failed to write gamut output.\n");
return -1;
}
// Also, if requested, decode and reencode the uncorrected input image.
if (!FLAGS_uncorrected.isEmpty()) {
SkBitmap bitmap;
int width = codec->getInfo().width();
int height = codec->getInfo().height();
SkAlphaType alphaType = codec->getInfo().alphaType();
bitmap.allocN32Pixels(width, height, kOpaque_SkAlphaType == alphaType);
SkImageInfo decodeInfo = SkImageInfo::MakeN32(width, height, alphaType);
if (SkCodec::kSuccess != codec->getPixels(decodeInfo, bitmap.getPixels(),
bitmap.rowBytes())) {
SkDebugf("Could not decode input image.\n");
return -1;
}
out.reset(SkImageEncoder::EncodeData(bitmap, SkImageEncoder::kPNG_Type, 100));
if (!out) {
SkDebugf("Failed to encode uncorrected image.\n");
return -1;
}
SkFILEWStream bitmapStream(FLAGS_uncorrected[0]);
result = bitmapStream.write(out->data(), out->size());
if (!result) {
SkDebugf("Failed to write uncorrected image output.\n");
return -1;
}
}
return 0;
}
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