vb中怎么压缩JPG

vb中如何压缩JPG
vb中如何压缩JPG,也就是降低图片的质量，谢谢

[解决办法]
dim picf as StdPicture,picfs as string
picfs = "e:\waps\ " & users & "\a\photo " & Photos(id) & "_sall.jpg "
set picf =LoadPicture(picfs)
Call SavePic(picf, picfs, "jpg ")