这里是我根据gif图像格式想出来的判断gif图像尺寸的方法，请大家给点意见
up.htm
up.asp
<%
FormSize = Request.TotalBytes
FormData = Request.BinaryRead( FormSize )
bncrlf=chrb(13) & chrb(10)
divider=leftb(formdata,instrb(formdata,bncrlf)-1)
datastart=instrb(formdata,bncrlf & bncrlf)+4
dataend=instrb(datastart+1,formdata,divider)-datastart
Image=midb(formdata,datastart,dataend)
head_version = Ascb( midb( Image,1,3 ) )
head_subversion = Ascb( midb( Image,4,3 ) )
head_width_l = Ascb( midb( Image,7,1 ) )
head_width_h = Ascb( midb( Image,8,1 ) )
head_height_l = Ascb( midb( Image,9,1 ) )
head_height_h = Ascb( midb( Image,10,1 ) )
head_colors = Ascb( midb( Image, 11, 1 ) )
head_width_h = head_width_h * 256
head_height_h = head_height_h * 256
head_colors = head_colors And &H07
Response.Write "图像大小为" & head_width_h + head_width_l & "x" & head_height_h + head_height_l _
& "x" & 2^( head_colors + 1 )
%>
