如何动态生成WBMP？

<%@ Language=VBScript %>

<%

Function StoB(varstr)

str2bin = ""

For i = 1 To Len(varstr)

varchar = Mid(varstr, i, 1)

str2bin = str2bin & ChrB(AscB(varchar))

Next

StoB = str2bin

End Function

img=chr(0) & chr(0) & chr(5) & chr(2) & chr(0) & chr(&Hf8)

Response.ContentType="image/vnd.wap.wbmp"

Response.BinaryWrite stob(img)

%>