修改inc\main.js文件，在第201行左右，找到

function bbimg(o){
var zoom=parseInt(o.style.zoom, 10)||100;zoom+=event.wheelDelta/12;if (zoom>0) o.style.zoom=zoom+'%';
return false;
}

改为

function bbimg(o){
// var zoom=parseInt(o.style.zoom, 10)||100;zoom+=event.wheelDelta/12;if (zoom>0) o.style.zoom=zoom+'%';
// return false;}

或者修改：把inc\Dv_ubbcode.asp 中的这个部分（大概在291行）

If ssize=500 Then
   s=re.replace(s,"<img$1 onmousewheel=""return bbimg(this)"" onload=""javascript:if(this.width>screen.width-"&ssize&")this.style.width=screen.width-"&ssize&";"">")
  Else
   s=re.replace(s,"<img$1 onmousewheel=""return bbimg(this)"" onload=""javascript:if(this.width>screen.width-"&ssize&")this.style.width=screen.width-"&ssize&";if(this.height>250)this.style.width=(this.width*250)/this.height;"">")

If ssize=500 Then
   s=re.replace(s,"<img$1onmousewheel=""return bbimg(this)"" onload=""javascript:if(this.width>screen.width-"&ssize&")this.width=screen.width-"&ssize&";"">")
  Else
   s=re.replace(s,"<img$1onload=""javascript:if(this.width>screen.width-"&ssize&")this.width=screen.width-"&ssize&";if(this.height>100)this.height=100;"">")
  End If

1、修改if(this.height>100)this.height=100;  为：if(this.height>100)this.style.height=100;  这样做可以保证大部分图片按比例缩放，只有少数特殊的图片会被变形。

2、修改if(this.height>100)this.height=100; 为：if (this.height>100){var rate=100 / this.height;this.style.width=this.width * rate;}