ASP判断远程图片是否存在的代码：

function CheckURL(byval A_strUrl)
set XMLHTTP = Server.CreateObject("Microsoft.XMLHTTP")
XMLHTTP.open "HEAD",A_strUrl,false
XMLHTTP.send()
CheckURL=(XMLHTTP.status=200)

set XMLHTTP = nothing
end function

Dim imgurl
imgurl="img/weste_net.gif"

if CheckURL(imgurl) then
response.write "图片存在"
else
response.write "图片不存在"
end if

还有用JavaScript来判断远程图片是否存在的代码：

var oReq = new ActiveXObject("Microsoft.XMLHTTP")
oReq.open("Get","img/weste_net.gif",false);
oReq.send();

if(oReq.status==404)
alert('不存在');
else
alert("存在")