[小代码]转换彩色图为灰度图

public Bitmap toGrayscale(Bitmap bmpOriginal) {
        final int height = bmpOriginal.getHeight();
        final int width = bmpOriginal.getWidth();

        final Bitmap bmpGrayscale = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);
        final Canvas c = new Canvas(bmpGrayscale);
        final Paint paint = new Paint();
        final ColorMatrix cm = new ColorMatrix();
        cm.setSaturation(0);
        final ColorMatrixColorFilter f = new ColorMatrixColorFilter(cm);
        paint.setColorFilter(f);
        c.drawBitmap(bmpOriginal, 0, 0, paint);
        return bmpGrayscale;
    }public Bitmap toGrayscale(Bitmap bmpOriginal) {