Converting images to grayscale

Color to Graysacle

 // making drawable grey
        ColorMatrix grayMatrix = new ColorMatrix();
        grayMatrix.setSaturation(0);
        ColorMatrixColorFilter grayscaleFilter = new ColorMatrixColorFilter(grayMatrix);
        //getting a drawable
        Drawable d = greyBtn.getBackground();
        d.setColorFilter(grayscaleFilter);
        greyBtn.setBackgroundDrawable(d);