GaussianFastBlur.java

package quickutils.core.blur.algorithms;

import android.graphics.Bitmap;

import quickutils.core.blur.IBlur;


/**
 * http://stackoverflow.com/a/13436737/774398
 * by gordi
 */
public class GaussianFastBlur implements IBlur {
    @Override
    public Bitmap blur(int radius, Bitmap original) {
        int w = original.getWidth();
        int h = original.getHeight();
        int[] pix = new int[w * h];
        original.getPixels(pix, 0, w, 0, 0, w, h);

        for(int r = radius; r >= 1; r /= 2) {
            for(int i = r; i < h - r; i++) {
                for(int j = r; j < w - r; j++) {
                    int tl = pix[(i - r) * w + j - r];
                    int tr = pix[(i - r) * w + j + r];
                    int tc = pix[(i - r) * w + j];
                    int bl = pix[(i + r) * w + j - r];
                    int br = pix[(i + r) * w + j + r];
                    int bc = pix[(i + r) * w + j];
                    int cl = pix[i * w + j - r];
                    int cr = pix[i * w + j + r];

                    pix[(i * w) + j] = 0xFF000000 |
                            (((tl & 0xFF) + (tr & 0xFF) + (tc & 0xFF) + (bl & 0xFF) + (br & 0xFF) + (bc & 0xFF) + (cl & 0xFF) + (cr & 0xFF)) >> 3) & 0xFF |
                            (((tl & 0xFF00) + (tr & 0xFF00) + (tc & 0xFF00) + (bl & 0xFF00) + (br & 0xFF00) + (bc & 0xFF00) + (cl & 0xFF00) + (cr & 0xFF00)) >> 3) & 0xFF00 |
                            (((tl & 0xFF0000) + (tr & 0xFF0000) + (tc & 0xFF0000) + (bl & 0xFF0000) + (br & 0xFF0000) + (bc & 0xFF0000) + (cl & 0xFF0000) + (cr & 0xFF0000)) >> 3) & 0xFF0000;
                }
            }
        }
        original.setPixels(pix, 0, w, 0, 0, w, h);
        return original;
    }
}