差影法的源程序。要注意的是，第一幅图的文件名为c:\test.bmp，第二幅图的文件名是c:\backgnd.bmp。它们有着相同的灰度值和调色板。执行时，这两个文件都已经准备好。我们针对的虽然是二值图，但为了处理的方便，用的是256级灰度图，不过只用到了0和255两种灰度级。-Subtraction of the source program. Note that, the first picture file named C : \ test.bmp, second picture file name is C: \ backgnd.bmp. They have the same gray scale value and palette. When executed, the two documents are ready. We although aimed at value of two plans, but in order to facilitate the, use of 256 grayscale, but to only 0and 255of two kinds of gray level.