If the images needs to be read off the video card only to be copied back to the video card in another process, it is usually not worthwhile using accelerated rendering in the first place.

• 如果从图形卡中读取图像数据仅仅是为了在另一个进程中把这些数据复制回图形卡中，使用加速的渲染通常首先就是不值得的。