Created
August 4, 2014 10:19
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FastBlur with downscaling for faster performance
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import android.content.Context; | |
import android.graphics.Bitmap; | |
import android.util.Log; | |
public class Blur { | |
public static Bitmap fastblur(Context context, Bitmap sentBitmap, int radius) { | |
float scaleFactor = 8; | |
Bitmap bitmap = Bitmap.createScaledBitmap(sentBitmap, (int) (sentBitmap.getWidth() / scaleFactor), (int) (sentBitmap.getHeight() / scaleFactor), true); | |
sentBitmap = bitmap; | |
long time = System.currentTimeMillis(); | |
if (radius < 1) { | |
return (null); | |
} | |
int w = bitmap.getWidth(); | |
int h = bitmap.getHeight(); | |
int[] pix = new int[w * h]; | |
bitmap.getPixels(pix, 0, w, 0, 0, w, h); | |
int wm = w - 1; | |
int hm = h - 1; | |
int wh = w * h; | |
int div = radius + radius + 1; | |
int r[] = new int[wh]; | |
int g[] = new int[wh]; | |
int b[] = new int[wh]; | |
int rsum, gsum, bsum, x, y, i, p, yp, yi, yw; | |
int vmin[] = new int[Math.max(w, h)]; | |
int divsum = (div + 1) >> 1; | |
divsum *= divsum; | |
int dv[] = new int[256 * divsum]; | |
for (i = 0; i < 256 * divsum; i++) { | |
dv[i] = (i / divsum); | |
} | |
yw = yi = 0; | |
int[][] stack = new int[div][3]; | |
int stackpointer; | |
int stackstart; | |
int[] sir; | |
int rbs; | |
int r1 = radius + 1; | |
int routsum, goutsum, boutsum; | |
int rinsum, ginsum, binsum; | |
for (y = 0; y < h; y++) { | |
rinsum = ginsum = binsum = routsum = goutsum = boutsum = rsum = gsum = bsum = 0; | |
for (i = -radius; i <= radius; i++) { | |
p = pix[yi + Math.min(wm, Math.max(i, 0))]; | |
sir = stack[i + radius]; | |
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 = radius; | |
for (x = 0; x < w; x++) { | |
r[yi] = dv[rsum]; | |
g[yi] = dv[gsum]; | |
b[yi] = dv[bsum]; | |
rsum -= routsum; | |
gsum -= goutsum; | |
bsum -= boutsum; | |
stackstart = stackpointer - radius + div; | |
sir = stack[stackstart % div]; | |
routsum -= sir[0]; | |
goutsum -= sir[1]; | |
boutsum -= sir[2]; | |
if (y == 0) { | |
vmin[x] = Math.min(x + radius + 1, wm); | |
} | |
p = pix[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 += w; | |
} | |
for (x = 0; x < w; x++) { | |
rinsum = ginsum = binsum = routsum = goutsum = boutsum = rsum = gsum = bsum = 0; | |
yp = -radius * w; | |
for (i = -radius; i <= radius; i++) { | |
yi = Math.max(0, yp) + x; | |
sir = stack[i + radius]; | |
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 < hm) { | |
yp += w; | |
} | |
} | |
yi = x; | |
stackpointer = radius; | |
for (y = 0; y < h; y++) { | |
// Preserve alpha channel: ( 0xff000000 & pix[yi] ) | |
pix[yi] = (0xff000000 & pix[yi]) | (dv[rsum] << 16) | |
| (dv[gsum] << 8) | dv[bsum]; | |
rsum -= routsum; | |
gsum -= goutsum; | |
bsum -= boutsum; | |
stackstart = stackpointer - radius + div; | |
sir = stack[stackstart % div]; | |
routsum -= sir[0]; | |
goutsum -= sir[1]; | |
boutsum -= sir[2]; | |
if (x == 0) { | |
vmin[y] = Math.min(y + r1, hm) * w; | |
} | |
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 += w; | |
} | |
} | |
bitmap.setPixels(pix, 0, w, 0, 0, w, h); | |
Log.v("Blur", "Time elapsed: " + (System.currentTimeMillis() - time)); | |
return bitmap; | |
} | |
} |
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