Android - create gray scale image from drawable

GrayScaleAndroid

 private Drawable getGrayScaleDrawable() {
        int id = getAreaCharacterId();
        Bitmap bmp = BitmapFactory.decodeResource(getResources(),id);
        int width = bmp.getWidth();
        int height = bmp.getHeight();

        Bitmap grayScale = Bitmap.createBitmap(width,height, Bitmap.Config.ARGB_8888);
        Canvas c = new Canvas(grayScale);
        Paint paint = new Paint();
        ColorMatrix cm = new ColorMatrix();
        cm.setSaturation(0);
        ColorMatrixColorFilter f = new ColorMatrixColorFilter(cm);
        paint.setColorFilter(f);
        c.drawBitmap(bmp, 0, 0, paint);

        Drawable grayed = new BitmapDrawable(getResources(),grayScale);

        bmp.recycle();
//        grayScale.recycle();

        return grayed;
    }
    
     private int getAreaCharacterId() {
        int id = 0;

        switch (mSelected){
            case 1:
                id = R.drawable.angel;
                break;
            case 2:
                id =R.drawable.ginger;
                break;
            case 3:
                id =R.drawable.snowman;
                break;
            case 4:
                id =R.drawable.reindeer;
                break;
            case 5:
                id =R.drawable.santa;
                break;
            case 6:
                id =R.drawable.elf;
                break;
        }

        return id;
    }