Index: tools/visualize_color_gamut.cpp |
diff --git a/tools/visualize_color_gamut.cpp b/tools/visualize_color_gamut.cpp |
new file mode 100644 |
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+++ b/tools/visualize_color_gamut.cpp |
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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.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; |
+} |