compare

代码说明：

  直方图是以图形化参数来显示图片曝光精确度的手段，其描述的是图片显示范围内影像的灰度分布曲线。它可以帮助分析图片的曝光水平等一些信息。(Histogram is a graphical display picture exposure parameters to measure the accuracy of its description is the picture display grayscale images within the distribution curve. It can help you analyze the picture and some information on exposure levels.)