下面三个保存图像是一样的,即:'jpeg'='jpeg 0'='jpeg 75'
write_image (Deskimage2, 'jpeg', 0,'E:/TestPic/jpegdeskimage2.jpeg')
write_image (Deskimage2, 'jpeg 0', 0,'E:/TestPic/jpeg0deskimage2.jpeg')
write_image (Deskimage2, 'jpeg 75', 0,'E:/TestPic/jpeg75deskimage2.jpeg')
write_image (Deskimage2, 'jpeg 100', 0,'E:/TestPic/jpeg75deskimage2.jpeg') 图像质量最好,所占空间最大。