*生成0到255的灰度图像
*原型如下：gen_image_surface_first_order( : ImageSurface : Type, Alpha, Beta, Gamma, Row, Column, Width, Height : )
gen_image_surface_first_order(ImageSurface,'byte',0,1,1,0,0,512,512)
*灰度值在0到128的生成区域Region3
threshold(ImageSurface,Region3,0,128)
dev_display(ImageSurface)
*灰度值在128到255的生成区域Region4
threshold(ImageSurface,Region4,128,255)
