freejung - 3:21 pm on Jul 6, 2011 (gmt 0)
I have such a site, but my setup is quite different.
I have a separate HTML page for each image. There are a number of advantages to this, including that thumbnail clicks get tracked as a normal page view.
I offer several different resolutions, and the links to each file have the GA event tracking script attached to the onclick handler. I've been tracking downloads since long before Panda, it's one of my most important metrics.
Of course, I got pandalized anyway, but I think that is not because of my download mechanism but for other reasons.
After Panda, I considered switching to a setup like the one you describe, to get rid of all of the "thin" image pages. I thought it through and changed my mind. There are still lots of good reasons for each image to have its own unique page.
From Google's guidelines for publishing images (emphasis in the original):
Even if your image appears on several pages on your site, consider creating a standalone landing page for each image, where you can gather all its related information. If you do this, be sure to provide unique information—such as descriptive titles and captions—on each page.