see
Title: SavePicture(): Can I Force Output to 256 Colors?
http://www.experts-exchange.com/Programming/Programming_Languages/Visual_Basic/Q_10146062.html
Title: SavePicture(): Can I Force Output to 256 Colors?
http://www.experts-exchange.com/Programming/Programming_Languages/Visual_Basic/Q_10146062.html
注意把下载后的*.zip.jpg改名成*.zip进行相应的抖动运算,再保存就能生成不同格式的BMP由于它对DIB的图像数据进行操作,所以速度很快
由于它用了有序抖动,所以效果比较好