blur static method

    private static WeakReference<RenderScript> rsRef = new WeakReference<>(null);
    private static WeakReference<ScriptIntrinsicBlur> blurScriptRef = new WeakReference<>(null);

    /**
     * Use {@link RenderScript} to blur bitmap.
     *
     * @param bitmap to be blurred
     * @param radius of blur
     * @throws RSRuntimeException when some .so libs are not available (e.g. on Genymotion emulator)
     */
    public static synchronized void applyBlur(Context context, Bitmap bitmap, Float radius) throws RSRuntimeException {
        RenderScript rs = rsRef.get();
        if (rs == null) {
            rs = RenderScript.create(context.getApplicationContext());
            rsRef = new WeakReference<>(rs);
        }
        //this will blur the bitmap with a provided radius and save it in bitmap
        final Allocation input = Allocation.createFromBitmap(rs, bitmap, Allocation.MipmapControl.MIPMAP_NONE, Allocation.USAGE_SCRIPT | Allocation.USAGE_SHARED);
        final Allocation output = Allocation.createTyped(rs, input.getType());

        ScriptIntrinsicBlur blurScript = blurScriptRef.get();
        if (blurScript == null) {
            blurScript = ScriptIntrinsicBlur.create(rs, Element.U8_4(rs));
            blurScriptRef = new WeakReference<>(blurScript);
        }

        blurScript.setRadius(radius);
        blurScript.setInput(input);
        blurScript.forEach(output);
        output.copyTo(bitmap);
    }