This is a Picasso transform that blurs and darkens an image.

blur_darken_transform

private final class BlurTransform implements Transformation {

        WeakReference<Context> context;

        public BlurTransform(Context context) {
            super();
            this.context = new WeakReference<>(context);
        }

        @Override
        public Bitmap transform(Bitmap bitmap) {
            RenderScript rs = RenderScript.create(context.get());
            Bitmap source = bitmap.copy(Bitmap.Config.ARGB_8888, true);

            if (source == null) {
                return null;
            }

            Allocation input = Allocation.createFromBitmap(rs, source,
                    Allocation.MipmapControl.MIPMAP_NONE, Allocation.USAGE_SCRIPT);
            Allocation output = Allocation.createTyped(rs, input.getType());
            ScriptIntrinsicBlur script = ScriptIntrinsicBlur.create(rs, Element.U8_4(rs));
            script.setRadius(17);
            script.setInput(input);
            script.forEach(output);
            output.copyTo(source);

            // also darken the image
            Paint paint = new Paint();
            ColorFilter filter = new LightingColorFilter(0xFF444444, 0x66666666);
            paint.setColorFilter(filter);
            Canvas canvas = new Canvas(source);
            canvas.drawBitmap(source, 0, 0, paint);

            bitmap.recycle();

            return source;
        }

        @Override
        public String key() {
            return "blur";
        }

    }