BMP图像文件的操作，编写C++程序，可以将一个标准24bit真彩色BMP文件中三基色图像提取出来存成独立的8bit灰度图像（BMP）-The operation of the BMP image file, write C++ program trichromatic image in a standard 24bit true color BMP files can be extracted to be saved as a separate 8bit grayscale images (B