RenderScript use when API > 16.

Calculation time is 2 times faster in this case.

BlurEffect/src/com/npi/blureffect/Blur.java

@@ -1,13 +1,36 @@
 package com.npi.blureffect;
 
+import android.annotation.SuppressLint;
+import android.content.Context;
 import android.graphics.Bitmap;
+import android.os.Build.VERSION;
+import android.renderscript.Allocation;
+import android.renderscript.Element;
+import android.renderscript.RenderScript;
+import android.renderscript.ScriptIntrinsicBlur;
 import android.util.Log;
 
 public class Blur {
 
 	private static final String TAG = "Blur";
 
-	public static Bitmap fastblur(Bitmap sentBitmap, int radius) {
+	@SuppressLint("NewApi")
+	public static Bitmap fastblur(Context context, Bitmap sentBitmap, int radius) {
+
+		if (VERSION.SDK_INT > 16) {
+			Bitmap bitmap = sentBitmap.copy(sentBitmap.getConfig(), true);
+
+			final RenderScript rs = RenderScript.create(context);
+			final Allocation input = Allocation.createFromBitmap(rs, sentBitmap, Allocation.MipmapControl.MIPMAP_NONE,
+					Allocation.USAGE_SCRIPT);
+			final Allocation output = Allocation.createTyped(rs, input.getType());
+			final ScriptIntrinsicBlur script = ScriptIntrinsicBlur.create(rs, Element.U8_4(rs));
+			script.setRadius(radius /* e.g. 3.f */);
+			script.setInput(input);
+			script.forEach(output);
+			output.copyTo(bitmap);
+			return bitmap;
+		}
 
 		// Stack Blur v1.0 from
 		// http://www.quasimondo.com/StackBlurForCanvas/StackBlurDemo.html

BlurEffect/src/com/npi/blureffect/MainActivity.java

@@ -78,9 +78,9 @@ public void run() {
 
 					// No image found => let's generate it!
 					BitmapFactory.Options options = new BitmapFactory.Options();
-					options.inSampleSize = 4;
+					options.inSampleSize = 2;
 					Bitmap image = BitmapFactory.decodeResource(getResources(), R.drawable.image, options);
-					Bitmap newImg = Blur.fastblur(image, 12);
+					Bitmap newImg = Blur.fastblur(MainActivity.this, image, 12);
 					ImageUtils.storeImage(newImg, blurredImage);
 					runOnUiThread(new Runnable() {