[Javascript] image control in Netscape

[Dave]

Hi,
    I have overcome the problem of getting my full sized images (from
thumbnails) to be displayed onto a single html page with my matching
website background but have run into a new problem. When the 320 x 240
image opens in IE it looks 320 x 240, but when the same image opens in
Netscape (4.78) it is inflated in size and looks blurry. Here is the
line that I am using to display the image:
document.write("<a href=\"javascript:history.back()\"><img
src=\""+window.location.search.substring(1,window.location.search.length)+"\"
height=90% border=2 alt=\"back to index\"></a>");

See anything I could do to fix that from here? The image is called from
another webpage using the following:

<td align="center"><A HREF="viewer.html?./mypicture.jpg">

and is a 640x480 original shrunk to 320x240 to clear it up a bit and
then saved as a jpg. Thanks in advance for any and all possible fixes...

Dave K (in Florida USA)