javascript等比例压缩图片

<! DOCTYPE html public "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd" >
< html  xmlns ="http://www.w3.org/1999/xhtml" >
  < head >
     < title > jscript等比例压缩图片 </ title >
     < meta  http-equiv ="Content-Type"  content ="text/html; charset=gb2312"   />
     < script  type ="text/javascript"   >
        function ctlImg(img,w,h)
        {
            var img_Width  = w;
            var img_Height = h;
            var Owth = img.width;
            var Ohth = img.height;
            if(img.width>img_Width && img.height>img_Height){
                if(Owth/img_Width > Ohth/img_Height){
                    img.width = img_Width;
                    img.height = parseInt(img_Width/Owth * Ohth);
                }
                else{
                    img.height = img_Height;
                    img.width  = parseInt(img_Height/Ohth * Owth);
                }
                return true;
            }
            if(Owth>img_Width){
                img.width = img_Width;
                img.height = parseInt(img_Width * (Ohth/Owth));
            }else if(Ohth>img_Height){
                img.height = img_Height;
                img.width  = parseInt(img_Height * (Owth/Ohth));
            }
            return true;
        }
</ script >
  </ head >

  < body >
     < h1 > jscript等比例压缩图片 </ h1 >
     < img  onload ="ctlImg(this,300,200);"  src ="http://www.tu888.cn/tesetuku/minghuabizhi/md61.jpg"   />
     < img  onload ="ctlImg(this,200,100);"  src ="http://www.tu888.cn/tesetuku/minghuabizhi/md61.jpg"   />
     < img  onload ="ctlImg(this,100,100);"  src ="http://www.tu888.cn/tesetuku/minghuabizhi/md61.jpg"   />
     < img  onload ="ctlImg(this,200,50);"  src ="http://www.tu888.cn/tesetuku/minghuabizhi/md61.jpg"   />
  </ body >
</ html >