static bool is_wide_gamut(const skcms_ICCProfile& profile) {
// Determine if the source image has a gamut that is wider than sRGB. If so, we
// will use P3 as the output color space to avoid clipping the gamut.
if (profile.has_toXYZD50) {
SkPoint rgb[3];
load_gamut(rgb, profile.toXYZD50);
return calculate_area(rgb) > kSRGB_D50_GamutArea;
}
return false;
}
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(" X Y Z\n");
SkDebugf("Red %.3f %.3f %.3f\n", xyz.get(0, 0), xyz.get(0, 1), xyz.get(0, 2));
SkDebugf("Green %.3f %.3f %.3f\n", xyz.get(1, 0), xyz.get(1, 1), xyz.get(1, 2));
SkDebugf("Blue %.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>\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;
}
