I was wondering if 301s work OK with images. I assume that they would.
Recently we changed the location and file name of tens of thousands of graphics in a long overdue tidy up, and of course some of them got missed.
I have had some success with intelligent 404 pages in the past - see
http://hahomes.com/348 as an example, which goes to the custom 404 page, invisibly, since page or folder 348 doesn't exist, then recognises that 348 is a property code, and finds the correct page.
Not quite the same, as it is a 301 on a page, not on a graphic, but I wondered if this ought to work just as well with graphics.
Mod Rewrite isn't going to work, as there are so many images - it would make a huge file! Pity we can't use PHP in htaccess files...
Has anyone done 301s on graphics, or got any thoughts?