编程思路：

　　该程序只针对24位彩色位图，不适用于灰度位图。当原图的像素点为蓝色时，将　　　　　　显示屏幕上该位置的像素点像素值置为绿色，否则不变，将原图像素值赋给新图。

-Programming ideas: it is only for 24-bit color bitmap does not apply to grayscale bitmap. When the original image pixel is blue, will be displayed on the screen, the location of the pixel pixel value is set to green, otherwise unchanged, the original image pixel value is assigned to the new plan.