Add interesting features to visualize_color_gamut

tools/visualize_color_gamut.cpp

 /*
  * 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.");
+DEFINE_bool(sRGB, false, "Draws the sRGB gamut.");
+DEFINE_bool(adobeRGB, false, "Draws the Adobe RGB gamut.");
 
 /**
  *  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[]) {
+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("          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.
+    float xScale = 2071.25f; // Num pixels from 0 to 1 in x
+    float xOffset = 241.0f;  // Num pixels until start of x-axis
+    float yScale = 2067.78f; // Num pixels from 0 to 1 in y
+    float yOffset = -144.78; // 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");
+            "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>\n"
+            "Description: Writes a visualization of the color gamut to the output image  ."
+                         "Also, 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;
     }
 
     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)) {
+    SkBitmap gamut;
+    if (!GetResourceAsBitmap("gamut.png", &gamut)) {
         SkDebugf("Program failure.\n");
         return -1;
     }
-    SkCanvas canvas(bitmap);
+    SkCanvas canvas(gamut);
 
+    // Draw the sRGB gamut if requested.
+    if (FLAGS_sRGB) {
+        sk_sp<SkColorSpace> sRGBSpace = SkColorSpace::NewNamed(SkColorSpace::kSRGB_Named);
+        draw_gamut(&canvas, sRGBSpace->xyz(), "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, adobeRGBSpace->xyz(), "Adobe RGB", 0xFF31a9e1, false);
+    }
+
+    // Draw gamut for the input image.
     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);
     }
+    draw_gamut(&canvas, colorSpace->xyz(), input, 0xFF000000, true);
 
-    // 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));
+    // Finally, encode the result to the output file.
+    SkAutoTUnref<SkData> out(SkImageEncoder::EncodeData(gamut, SkImageEncoder::kPNG_Type, 100));
     if (!out) {
-        SkDebugf("Failed to encode output.\n");
+        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 output.\n");
+        SkDebugf("Failed to write gamut output.\n");
         return -1;
     }
 
+    // Also, decode and reencode the uncorrected input image.
+    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;
+    }
+    SkString path(input);

[jcgregorio, 2016/05/27 20:00:38]

The output path for the uncorrected input image should be set via flag. If the
flag isn't set then the image shouldn't be written, or use the current code as
the default path, whatever makes more sense.

[msarett, 2016/05/27 20:30:59]

Ok I've added the flag.  There is no default, so we won't waste time reencoding
the image unless it is requested.

+    path.append(".png");
+    SkFILEWStream bitmapStream(path.c_str());
+    result = bitmapStream.write(out->data(), out->size());
+    if (!result) {
+        SkDebugf("Failed to write uncorrected image output.\n");
+        return -1;
+    }
+
     return 0;
 }