Represent an RGB image as a float array

Image.java

import javax.imageio.ImageIO;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;

public class Image {

    public static Image read(String name) throws IOException {
        return new Image(ImageIO.read(new File(name)));
    }

    public static void save(Image image, String name) throws IOException {
        ImageIO.write(image.toBufferedImage(), "png", new File(name));
    }

    private final float[] image;
    private final int w, h;

    public Image(int w, int h) {
        this.w = w;
        this.h = h;
        this.image = new float[w * h * 3];
    }

    public Image(BufferedImage image) {
        this(image.getWidth(), image.getHeight());

        for(int y = 0; y < h; y++) {
            for(int x = 0; x < w; x++) {
                setRGB(x, y, image.getRGB(x, y));
            }
        }
    }

    public Image(int w, int h, float[] image) {
        this.w = w;
        this.h = h;
        this.image = image;
    }

    private int indexOf(int x, int y) {
        return ((w * y) + x) * 3;
    }

    public void setRGB(int x, int y, final int RGB) {
        float R = (((RGB >> 16) & 0xFF) / 255.0f);
        float G = (((RGB >>  8) & 0xFF) / 255.0f);
        float B = ((RGB & 0xFF) / 255.0f);
        setR(x, y, R);
        setG(x, y, G);
        setB(x, y, B);
    }

    private void set(int index, float n) {
        this.image[index] = n;
    }

    public void setR(int x, int y, float n) {
        set(indexOf(x, y), n);
    }

    public void setG(int x, int y, float n) {
        set(indexOf(x, y) + 1, n);
    }

    public void setB(int x, int y, float n) {
        set(indexOf(x, y) + 2, n);
    }

    public int getRGB(int x, int y) {
        int R = (int) (getR(x, y) * 255.0f);
        int G = (int) (getG(x, y) * 255.0f);
        int B = (int) (getB(x, y) * 255.0f);
        return 0xFF000000 | (R << 16) | (G << 8) | B;
    }

    private float get(int index) {
        return this.image[index];
    }

    public float getR(int x, int y) {
        return get(indexOf(x, y));
    }

    public float getG(int x, int y) {
        return get(indexOf(x, y) + 1);
    }

    public float getB(int x, int y) {
        return get(indexOf(x, y) + 2);
    }

    public int getW() {
        return w;
    }

    public int getH() {
        return h;
    }

    public int getSize() {
        return (w * h);
    }

    public float[] asArray() {
        return image;
    }

    public BufferedImage toBufferedImage() {
        BufferedImage image = new BufferedImage(w, h, BufferedImage.TYPE_INT_RGB);

        for(int y = 0; y < h; y++) {
            for(int x = 0; x < w; x++) {
                image.setRGB(x, y, this.getRGB(x, y));
            }
        }

        return image;
    }

    public float diff(final Image that) {
        final int w = Math.min(this.getW(), that.getW());
        final int h = Math.min(this.getH(), that.getH());
        return diff(that, 0, 0, w, h);
    }

    public float diff(final Image that, int x, int y, int w, int h) {
        final int size = (w * h);

        float s = 0;
        for(int yy = 0; yy < h; yy++) {
            for(int xx = 0; xx < w; xx++) {
                final float d = this.diff(that, x + xx, y + yy);
                s += (d * d);
            }
        }

        return (float) Math.sqrt(s / size);
    }

    private float diff(final Image that, int x, int y) {
        final float R = this.getR(x, y) - that.getR(x, y);
        final float G = this.getG(x, y) - that.getG(x, y);
        final float B = this.getB(x, y) - that.getB(x, y);

        final float s = (R * R) + (G * G) + (B * B);
        return (float) Math.sqrt(s / 3.0f); // RMSE
    }
}

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