Merge branch 'LuminanceClosestColour'

doc/readme.md

@@ -36,7 +36,7 @@ resolution).
 ### Installation/Usage
 If you have Java installed just double click the Img2ZXSpec.jar
 file (like you would a regular .exe file). If you don't have Java
-you need to get it first - <http://www.java.com/getjava>
+you need to get it first - <https://www.oracle.com/java/technologies/downloads/>
 The easiest way to learn how to use Image to Zx Spec is just to play with 
 it, you can even change most image options during image conversion.
 For information on advanced features read on...
@@ -265,13 +265,11 @@ reduce attribute artifact edges.
 
 #### Colour Distance Algorithm
 When making a decision on which Spectrum colours best match those of the source 
-image's pixels a colour space "distance" is evaluated.
+image's pixels an RGB colour space "distance" is evaluated.
 The choice of algorithm for this evaluation is configured here - typically
-the Compuphase algorithm is the best and uses heuristics based on human vision,
+the Luminance or Compuphase algorithms perform the best and use heuristics based on human vision,
 the classic Image to ZX Spec algorithm next (which is just a simple sum of RGB space distances), 
-followed by the Euclidean which is the straight line distance in RGB space. You may find
-any one of these better suits your use case, typically the latter two are interchangeable however
-classic tends to occasionally favour darker colours which can lead to better results.
+followed by the Euclidean which is the straight line distance in RGB space.
 
 #### Video Import Engine
 By default Image to ZX Spec's uses HumbleVideo which is fast platform native video

src/main/java/uk/co/silentsoftware/config/OptionsObject.java

@@ -31,10 +31,7 @@
 import uk.co.silentsoftware.core.converters.video.HumbleVideoImportEngine;
 import uk.co.silentsoftware.core.converters.video.VLCVideoImportEngine;
 import uk.co.silentsoftware.core.converters.video.VideoImportEngine;
-import uk.co.silentsoftware.core.helpers.colourdistance.ClassicColourDistanceStrategy;
-import uk.co.silentsoftware.core.helpers.colourdistance.ColourDistanceStrategy;
-import uk.co.silentsoftware.core.helpers.colourdistance.CompuphaseColourDistanceStrategy;
-import uk.co.silentsoftware.core.helpers.colourdistance.EuclideanColourDistance;
+import uk.co.silentsoftware.core.helpers.colourdistance.*;
 
 import java.util.ArrayList;
 import java.util.List;
@@ -246,6 +243,7 @@ public class OptionsObject {
 	private final List<ColourDistanceStrategy> colourDistancesModes;
 	{
 		colourDistancesModes = new ArrayList<>();
+		colourDistancesModes.add(new LuminanceColourDistance());
 		colourDistancesModes.add(new CompuphaseColourDistanceStrategy());
 		colourDistancesModes.add(new ClassicColourDistanceStrategy());
 		colourDistancesModes.add(new EuclideanColourDistance());

src/main/java/uk/co/silentsoftware/core/converters/image/processors/GigaScreenConverterImpl.java

@@ -202,8 +202,8 @@ private void orderByLuminosity(BufferedImage output1, BufferedImage output2) {
             for (int x = 0; x + ATTRIBUTE_BLOCK_SIZE <= output1.getWidth() && y + ATTRIBUTE_BLOCK_SIZE <= output1.getHeight(); x += ATTRIBUTE_BLOCK_SIZE) {
                 int outRgb1[] = output1.getRGB(x, y, ATTRIBUTE_BLOCK_SIZE, ATTRIBUTE_BLOCK_SIZE, null, 0, ATTRIBUTE_BLOCK_SIZE);
                 int outRgb2[] = output2.getRGB(x, y, ATTRIBUTE_BLOCK_SIZE, ATTRIBUTE_BLOCK_SIZE, null, 0, ATTRIBUTE_BLOCK_SIZE);
-                float sum1 = luminositySum(outRgb1);
-                float sum2 = luminositySum(outRgb2);
+                double sum1 = luminositySum(outRgb1);
+                double sum2 = luminositySum(outRgb2);
                 if (sum1 > sum2) {
                     output1.setRGB(x, y, ATTRIBUTE_BLOCK_SIZE, ATTRIBUTE_BLOCK_SIZE, outRgb2, 0, ATTRIBUTE_BLOCK_SIZE);
                     output2.setRGB(x, y, ATTRIBUTE_BLOCK_SIZE, ATTRIBUTE_BLOCK_SIZE, outRgb1, 0, ATTRIBUTE_BLOCK_SIZE);

src/main/java/uk/co/silentsoftware/core/helpers/ColourHelper.java

@@ -24,6 +24,7 @@
 import uk.co.silentsoftware.core.colourstrategy.ColourChoiceStrategy;
 import uk.co.silentsoftware.core.converters.image.processors.GigaScreenAttribute;
 import uk.co.silentsoftware.core.converters.image.processors.GigaScreenAttribute.GigaScreenColour;
+import uk.co.silentsoftware.core.helpers.colourdistance.LuminanceColourDistance;
 
 import java.awt.*;
 import java.awt.image.BufferedImage;
@@ -142,22 +143,22 @@ public static GigaScreenAttribute.GigaScreenColour getClosestGigaScreenColour(in
 
 	/**
 	 * Calculates the luminosity total for a set of rgb values
-	 * based on the NTSC formula  Y = 0.299*r + 0.587*g + 0.114*b.
+	 * based on the NTSC formula
 	 *
 	 * @param rgbVals the rgb value sets
 	 * @return the luminosity sum
 	 */
-	public static float luminositySum(int[] rgbVals) {
-		float sum = 0;
+	public static double luminositySum(int[] rgbVals) {
+		double sum = 0;
 		for (int rgb : rgbVals) {
 			int[] rgbComponents = ColourHelper.intToRgbComponents(rgb);
 			sum += luminosity(rgbComponents[0], rgbComponents[1], rgbComponents[2]);
 		}
 		return sum;
 	}
 
-	private static float luminosity(int red, int green, int blue) {
-		return (float)((0.299 * red) + (0.587 * green) + (0.114 * blue));
+	private static double luminosity(int red, int green, int blue) {
+		return ((LuminanceColourDistance.LUMA_RED * red) + (LuminanceColourDistance.LUMA_GREEN* green) + (LuminanceColourDistance.LUMA_BLUE * blue));
 	}
 
 	/**

src/main/java/uk/co/silentsoftware/core/helpers/colourdistance/EuclideanColourDistance.java

@@ -22,12 +22,10 @@
  * Fast Euclidean colour distance calculation that doesn't consider human colour perception
  */
 public class EuclideanColourDistance implements ColourDistanceStrategy {
-
     @Override
     public double getColourDistance(int red, int green, int blue, int[] colourSetComps) {
         return Math.pow(red - colourSetComps[0], 2d) + Math.pow(green - colourSetComps[1], 2d) + Math.pow(blue - colourSetComps[2], 2d);
     }
-
     @Override
     public String toString() {
         return getCaption("adv_colour_dist_euclidean") ;

src/main/java/uk/co/silentsoftware/core/helpers/colourdistance/LuminanceColourDistance.java

@@ -0,0 +1,29 @@
+package uk.co.silentsoftware.core.helpers.colourdistance;
+
+import static uk.co.silentsoftware.config.LanguageSupport.getCaption;
+
+/**
+ * Luminance colour distance adapted from http://appleoldies.ca/a2b/DHGRColors2017.htm
+ */
+public class LuminanceColourDistance implements ColourDistanceStrategy {
+
+    public static final double LUMA_RED = 0.298839;
+    public static final double LUMA_GREEN = 0.586811;
+    public static final double LUMA_BLUE = 0.114350;
+
+    @Override
+    public double getColourDistance(int red, int green, int blue, int[] paletteComps) {
+        double luma1 = (red*LUMA_RED + green*LUMA_GREEN + blue*LUMA_BLUE) / (255.0*1000);
+        double luma2 = (paletteComps[0]*LUMA_RED + paletteComps[1]*LUMA_GREEN + paletteComps[2]*LUMA_BLUE) / (255.0*1000);
+        double lumaDiff = luma1-luma2;
+        double diffR = (paletteComps[0]-red)/255.0;
+        double diffG = (paletteComps[1]-green)/255.0;
+        double diffB = (paletteComps[2]-blue)/255.0;
+        return (diffR*diffR*LUMA_RED + diffG*diffG*LUMA_GREEN+ diffB*diffB*LUMA_BLUE)*0.75+ lumaDiff*lumaDiff;
+    }
+
+    @Override
+    public String toString() {
+        return getCaption("adv_colour_dist_luminance") ;
+    }
+}

src/main/resources/Messages_en.properties

@@ -76,6 +76,7 @@ adv_video_turbo=Turbo Mode (recommended off)
 adv_colour_dist_euclidean= Euclidean Comparison
 adv_colour_dist_compuphase=Compuphase Comparison
 adv_colour_dist_classic=Classic Comparison
+adv_colour_dist_luminance=Luminance Comparison
 adv_colour_dist=Colour Distance Algorithm
 
 #Misc Tab