let me say exactly what i did.
i took some pics with my digital camara at 3.1 mp. then i used windows image resizer power toy and saved them at 300 x 300. it brought the file size down to about 8kb so that they would be easy to upload and show up quickly on my site.
when i click them to show on the single product they are perfect in size. when i click larger image the size is about the same as the single pic. i have not lost any quality. all my pics look good.
i was reading though some posts and thought that the correct file to edit would be the popup_image.php file.
what happens is a small window comes in then loads the pic, resizes itself to a full screen, put the picture is still small.
i have read some on the images through post and what dr.byte has to say about handling images. i want to keep my site as fast and as clean as possible. other sites i am competing with are very content rich and take a while to load. i am on dial up and for me my site loads about 3 seconds longer than google's home page.
if i load them to their original size, i feel my site will suffer when someone click larger image.
thanks for your help and input.
ps i read one post also talking about as js file that might be the right one to play with.