Bonjour,

Voici 2 algorithmes que j'ai repris du site Mario Klingeman adaptés au Java pour faire un flou rapide suivant un certain rayon.

Le résultat est proche d'un flou gaussien, mais il peut y avoir certains artefacts pour de grosses images (>4000*4000).

V1 Box Blur :

Code java : Sélectionner tout - Visualiser dans une fenêtre à part
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/**
 * 
 */
package filmlooking;
 
import java.awt.image.BufferedImage;
 
import millie.plugins.GenericPluginFilter;
import millie.plugins.PluginInfo;
import millie.plugins.parameters.IntSliderParameter;
 
/**
 * 
 *  Inspiré du code de Mario Klingemann (incubator)
 *  
 * @author florent
 */
@PluginInfo(name = "Fast Blur", category = "Flou")
public class FastBlurFilter extends GenericPluginFilter {
 
	public FastBlurFilter() {
		setPluginName("Fast Blur");
		setRefreshable(true);
		setLongProcessing(true);
 
		addParameter(new IntSliderParameter("rayon", "Rayon", 1, 50, 3));
 
	}
 
	@Override
	public BufferedImage filter() throws Exception {
		BufferedImage input = getInputImage();
		BufferedImage output = new BufferedImage(input.getWidth(), input
				.getHeight(), input.getType());
		int rayon = getIntValue("rayon");
 
		int width = input.getWidth();
		int height = input.getHeight();
		int maxWH = Math.max(width, height);
 
		int widthm = width - 1;
		int heightm = height - 1;
		int aire = width * height;
		int div = 2 * rayon + 1;
		int r[] = new int[aire];
		int g[] = new int[aire];
		int b[] = new int[aire];
		int rsum, gsum, bsum, p, p1, p2, yp, yi, yw;
		int vmin[] = new int[maxWH];
		int vmax[] = new int[maxWH];
 
		int[] pixels = input.getRGB(0, 0, width, height, null, 0, width);
 
		int dv[] = new int[256 * div];
		for (int i = 0; i < 256 * div; i++) {
			dv[i] = (i / div);
		}
 
		yw = yi = 0;
 
		for (int y = 0; y < height; y++) {
			rsum = gsum = bsum = 0;
			for (int i = -rayon; i <= rayon; i++) {
				p = pixels[yi + Math.min(widthm, Math.max(i, 0))];
				rsum += (p & 0xff0000) >> 16;
				gsum += (p & 0x00ff00) >> 8;
				bsum += p & 0x0000ff;
			}
			for (int x = 0; x < width; x++) {
 
				r[yi] = dv[rsum];
				g[yi] = dv[gsum];
				b[yi] = dv[bsum];
 
				if (y == 0) {
					vmin[x] = Math.min(x + rayon + 1, widthm);
					vmax[x] = Math.max(x - rayon, 0);
				}
				p1 = pixels[yw + vmin[x]];
				p2 = pixels[yw + vmax[x]];
 
				rsum += ((p1 & 0xff0000) - (p2 & 0xff0000)) >> 16;
				gsum += ((p1 & 0x00ff00) - (p2 & 0x00ff00)) >> 8;
				bsum += (p1 & 0x0000ff) - (p2 & 0x0000ff);
				yi++;
			}
			yw += width;
		}
 
		for (int x = 0; x < width; x++) {
			rsum = gsum = bsum = 0;
			yp = -rayon * width;
			for (int i = -rayon; i <= rayon; i++) {
				yi = Math.max(0, yp) + x;
				rsum += r[yi];
				gsum += g[yi];
				bsum += b[yi];
				yp += width;
			}
			yi = x;
			for (int y = 0; y < height; y++) {
				pixels[yi] = 0xff000000 | (dv[rsum] << 16) | (dv[gsum] << 8)
						| dv[bsum];
				if (x == 0) {
					vmin[y] = Math.min(y + rayon + 1, heightm) * width;
					vmax[y] = Math.max(y - rayon, 0) * width;
				}
				p1 = x + vmin[y];
				p2 = x + vmax[y];
 
				rsum += r[p1] - r[p2];
				gsum += g[p1] - g[p2];
				bsum += b[p1] - b[p2];
 
				yi += width;
			}
		}
 
		output.setRGB(0, 0, width, height, pixels, 0, width);
		return output;
	}
 
}

V2 :
Code java : Sélectionner tout - Visualiser dans une fenêtre à part
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/**
 * 
 */
package filmlooking;
 
import java.awt.image.BufferedImage;
 
import millie.plugins.GenericPluginFilter;
import millie.plugins.PluginInfo;
import millie.plugins.parameters.IntSliderParameter;
 
/**
 * Inspiré du code de Mario Klingemann (incubator)
 * 
 * @author florent
 * 
 */
@PluginInfo(name = "Stack Blur", category = "Flou")
public class StackBlurFilter extends GenericPluginFilter {
 
	public StackBlurFilter() {
		setPluginName("Stack Blur");
		setRefreshable(true);
		setLongProcessing(true);
 
		addParameter(new IntSliderParameter("rayon", "Rayon", 1, 50, 3));
 
	}
 
	@Override
	public BufferedImage filter() throws Exception {
		BufferedImage input = getInputImage();
		BufferedImage output = new BufferedImage(input.getWidth(), input
				.getHeight(), input.getType());
		int rayon = getIntValue("rayon");
 
		int width = input.getWidth();
		int height = input.getHeight();
		int maxWH = Math.max(width, height);
 
		int widthm = width - 1;
		int heightm = height - 1;
		int aire = width * height;
		int div = 2 * rayon + 1;
		int r[] = new int[aire];
		int g[] = new int[aire];
		int b[] = new int[aire];
		int rsum, gsum, bsum, p, yp, yi = 0, yw = 0;
		int vmin[] = new int[maxWH];
 
		int[] pixels = input.getRGB(0, 0, width, height, null, 0, width);
 
		int divsum = (div + 1) >> 1;
		divsum *= divsum;
		int dv[] = new int[256 * divsum];
		for (int i = 0; i < 256 * divsum; i++) {
			dv[i] = (i / divsum);
		}
 
		int[][] stack = new int[div][3];
		int stackpointer;
		int stackstart;
		int[] sir;
		int rbs;
		int r1 = rayon + 1;
		int routsum, goutsum, boutsum;
		int rinsum, ginsum, binsum;
 
		for (int y = 0; y < height; y++) {
			rinsum = ginsum = binsum = routsum = goutsum = boutsum = rsum = gsum = bsum = 0;
			for (int i = -rayon; i <= rayon; i++) {
				p = pixels[yi + Math.min(widthm, Math.max(i, 0))];
				sir = stack[i + rayon];
				sir[0] = (p & 0xff0000) >> 16;
				sir[1] = (p & 0x00ff00) >> 8;
				sir[2] = (p & 0x0000ff);
				rbs = r1 - Math.abs(i);
				rsum += sir[0] * rbs;
				gsum += sir[1] * rbs;
				bsum += sir[2] * rbs;
				if (i > 0) {
					rinsum += sir[0];
					ginsum += sir[1];
					binsum += sir[2];
				} else {
					routsum += sir[0];
					goutsum += sir[1];
					boutsum += sir[2];
				}
			}
			stackpointer = rayon;
 
			for (int x = 0; x < width; x++) {
 
				r[yi] = dv[rsum];
				g[yi] = dv[gsum];
				b[yi] = dv[bsum];
 
				rsum -= routsum;
				gsum -= goutsum;
				bsum -= boutsum;
 
				stackstart = stackpointer - rayon + div;
				sir = stack[stackstart % div];
 
				routsum -= sir[0];
				goutsum -= sir[1];
				boutsum -= sir[2];
 
				if (y == 0) {
					vmin[x] = Math.min(x + rayon + 1, widthm);
				}
				p = pixels[yw + vmin[x]];
 
				sir[0] = (p & 0xff0000) >> 16;
				sir[1] = (p & 0x00ff00) >> 8;
				sir[2] = (p & 0x0000ff);
 
				rinsum += sir[0];
				ginsum += sir[1];
				binsum += sir[2];
 
				rsum += rinsum;
				gsum += ginsum;
				bsum += binsum;
 
				stackpointer = (stackpointer + 1) % div;
				sir = stack[(stackpointer) % div];
 
				routsum += sir[0];
				goutsum += sir[1];
				boutsum += sir[2];
 
				rinsum -= sir[0];
				ginsum -= sir[1];
				binsum -= sir[2];
 
				yi++;
			}
			yw += width;
		}
		for (int x = 0; x < width; x++) {
			rinsum = ginsum = binsum = routsum = goutsum = boutsum = rsum = gsum = bsum = 0;
			yp = -rayon * width;
			for (int i = -rayon; i <= rayon; i++) {
				yi = Math.max(0, yp) + x;
 
				sir = stack[i + rayon];
 
				sir[0] = r[yi];
				sir[1] = g[yi];
				sir[2] = b[yi];
 
				rbs = r1 - Math.abs(i);
 
				rsum += r[yi] * rbs;
				gsum += g[yi] * rbs;
				bsum += b[yi] * rbs;
 
				if (i > 0) {
					rinsum += sir[0];
					ginsum += sir[1];
					binsum += sir[2];
				} else {
					routsum += sir[0];
					goutsum += sir[1];
					boutsum += sir[2];
				}
 
				if (i < heightm) {
					yp += width;
				}
			}
			yi = x;
			stackpointer = rayon;
			for (int y = 0; y < height; y++) {
				pixels[yi] = 0xff000000 | (dv[rsum] << 16) | (dv[gsum] << 8)
						| dv[bsum];
 
				rsum -= routsum;
				gsum -= goutsum;
				bsum -= boutsum;
 
				stackstart = stackpointer - rayon + div;
				sir = stack[stackstart % div];
 
				routsum -= sir[0];
				goutsum -= sir[1];
				boutsum -= sir[2];
 
				if (x == 0) {
					vmin[y] = Math.min(y + r1, heightm) * width;
				}
				p = x + vmin[y];
 
				sir[0] = r[p];
				sir[1] = g[p];
				sir[2] = b[p];
 
				rinsum += sir[0];
				ginsum += sir[1];
				binsum += sir[2];
 
				rsum += rinsum;
				gsum += ginsum;
				bsum += binsum;
 
				stackpointer = (stackpointer + 1) % div;
				sir = stack[stackpointer];
 
				routsum += sir[0];
				goutsum += sir[1];
				boutsum += sir[2];
 
				rinsum -= sir[0];
				ginsum -= sir[1];
				binsum -= sir[2];
 
				yi += width;
			}
		}
 
		output.setRGB(0, 0, width, height, pixels, 0, width);
		return output;
 
	}
}


Exemple avec une image de 4200*2800.
Une convolution classique avec un rayon de 10 donne un temps de 30sec (sur ma machine)
Avec le deuxième algo, j'ai un temps de 5sec pour un rayon de 50 (ce qui est raisonnable avec la taille de l'image)

En haut à gauche, originale, en haut à droite, Fast Blur avec rayon 50, en bas à gauche, Stack Blur avec rayon 50