将ImageView变成灰色竟是如此简单

 ColorMatrix matrix = new ColorMatrix();
    matrix.setSaturation(0);
 
    ColorMatrixColorFilter filter = new ColorMatrixColorFilter(matrix);
    imageview.setColorFilter(filter);

另外PorterDuffColorFilter filter = new PorterDuffColorFilter(Color.GRAY, Mode.MULTIPLY);可以实现一些算数运算。