Whilst looking for something totally different I came across this good explanation of what to do with large images that you want to display on your web site.

Some of us would create a small thumbnail version of that image and link it to the original file. Works perfect but here’s an alternate approach that lets you embed full picture of virtually any size onto web pages without resizing.

You can see the full article here:-

Put Your Large Pictures in Web Pages without Resizing Them – Google Maps Image Viewer.