Add color spaces

src/main/java/com/marginallyclever/donatello/colorspace/ColorSpace.java

@@ -0,0 +1,24 @@
+package com.marginallyclever.donatello.colorspace;
+
+/**
+ * Interface for color space conversion to and from RGB.
+ */
+public interface ColorSpace {
+    /**
+     * Converts RGB values (0-1 range) to the target color space.
+     * @param r Red component (0-1)
+     * @param g Green component (0-1)
+     * @param b Blue component (0-1)
+     * @return Array of converted color space values.
+     */
+    float[] fromRGB(float r, float g, float b);
+
+    /**
+     * Converts from the target color space back to RGB (0-1 range).
+     * @param c1 First component of color space.
+     * @param c2 Second component of color space.
+     * @param c3 Third component of color space.
+     * @return Array with RGB values (0-1 range).
+     */
+    float[] toRGB(float c1, float c2, float c3);
+}

src/main/java/com/marginallyclever/donatello/colorspace/HSVColorSpace.java

@@ -0,0 +1,50 @@
+package com.marginallyclever.donatello.colorspace;
+
+/**
+ * A color space that converts between RGB and HSV.
+ */
+public class HSVColorSpace implements ColorSpace {
+    @Override
+    public float[] fromRGB(float r, float g, float b) {
+        float max = Math.max(r, Math.max(g, b));
+        float min = Math.min(r, Math.min(g, b));
+        float delta = max - min;
+
+        float h = 0f;
+        if (delta != 0) {
+            if (max == r) h = ((g - b) / delta) % 6;
+            else if (max == g) h = ((b - r) / delta) + 2;
+            else h = ((r - g) / delta) + 4;
+            h /= 6f;
+            if (h < 0) h += 1;
+        }
+
+        float s = (max == 0) ? 0 : (delta / max);
+        float v = max;
+        return new float[]{h, s, v};
+    }
+
+    @Override
+    public float[] toRGB(float h, float s, float v) {
+        float c = v * s;
+        float x = c * (1 - Math.abs((h * 6) % 2 - 1));
+        float m = v - c;
+
+        float r = 0, g = 0, b = 0;
+        int sector = (int)(h * 6) % 6;
+        switch (sector) {
+            case 0: r = c; g = x; break;
+            case 1: r = x; g = c; break;
+            case 2: g = c; b = x; break;
+            case 3: g = x; b = c; break;
+            case 4: r = x; b = c; break;
+            case 5: r = c; b = x; break;
+        }
+        return new float[]{r + m, g + m, b + m};
+    }
+
+    @Override
+    public String toString() {
+        return "HSV";
+    }
+}

src/main/java/com/marginallyclever/donatello/colorspace/LUVColorSpace.java

@@ -0,0 +1,29 @@
+package com.marginallyclever.donatello.colorspace;
+
+/**
+ * LUV color space conversion.
+ * https://framewave.sourceforge.net/Manual/fw_function_020_0060_00330.html
+ * preserve the D65 white point.
+ */
+public class LUVColorSpace implements ColorSpace {
+    @Override
+    public float[] fromRGB(float r, float g, float b) {
+        float x = r * 0.4124564f + g * 0.3575761f + b * 0.1804375f;
+        float y = r * 0.2126729f + g * 0.7151522f + b * 0.0721750f;
+        float z = r * 0.0193339f + g * 0.1191920f + b * 0.9503041f;
+        return new float[]{x,y,z};
+    }
+
+    @Override
+    public float[] toRGB(float x, float y, float z) {
+        float r = x *  3.2404542f + y * -1.5371385f + z * -0.4985314f;
+        float g = x * -0.9692660f + y *  1.8760108f + z *  0.0415560f;
+        float b = x *  0.0556434f + y * -0.2040259f + z *  1.0572252f;
+        return new float[]{r,g,b};
+    }
+
+    @Override
+    public String toString() {
+        return "LUV";
+    }
+}

src/main/java/com/marginallyclever/donatello/colorspace/RGBColorSpace.java

@@ -0,0 +1,21 @@
+package com.marginallyclever.donatello.colorspace;
+
+/**
+ * A color space that converts between RGB and RGB.
+ */
+public class RGBColorSpace implements ColorSpace {
+    @Override
+    public float[] fromRGB(float r, float g, float b) {
+        return new float[]{r, g, b};
+    }
+
+    @Override
+    public float[] toRGB(float c1, float c2, float c3) {
+        return new float[]{c1, c2, c3};
+    }
+
+    @Override
+    public String toString() {
+        return "RGB";
+    }
+}

src/main/java/com/marginallyclever/donatello/curveeditor/CurveEditor.java

@@ -18,13 +18,10 @@
 public class CurveEditor extends JPanel {
     private static class ControlPoint {
         Point2d position;
-        Point2d tangentIn;
-        Point2d tangentOut;
+        // TODO add bezier curve control points
 
         public ControlPoint(Point2d position) {
             this.position = position;
-            this.tangentIn = new Point2d();
-            this.tangentOut = new Point2d();
         }
     }
 

src/test/java/com/marginallyclever/donatello/colorspace/ColorSpaceTest.java

@@ -0,0 +1,38 @@
+package com.marginallyclever.donatello.colorspace;
+
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+
+public class ColorSpaceTest {
+    @Test
+    public void testToAndFromRGB() {
+        testToAndFrom(new RGBColorSpace());
+    }
+
+    @Test
+    public void testToAndFromLUT() {
+        testToAndFrom(new LUVColorSpace());
+    }
+
+    @Test
+    public void testToAndFromHSV() {
+        testToAndFrom(new HSVColorSpace());
+    }
+
+    private void testToAndFrom(ColorSpace colorSpace) {
+        for (int r = 0; r < 256; r++) {
+            for (int g = 0; g < 256; g++) {
+                for (int b = 0; b < 256; b++) {
+                    float r2 = r / 255f;
+                    float g2 = g / 255f;
+                    float b2 = b / 255f;
+                    float[] converted = colorSpace.fromRGB(r2, g2, b2);
+                    float[] after = colorSpace.toRGB(converted[0], converted[1], converted[2]);
+                    Assertions.assertEquals(after[0], r2, 0.01, r+","+g+","+b);
+                    Assertions.assertEquals(after[1], g2, 0.01, r+","+g+","+b);
+                    Assertions.assertEquals(after[2], b2, 0.01, r+","+g+","+b);
+                }
+            }
+        }
+    }
+}