Aardvark- Optimizing images for Google image search

Is the filename or alt tag more important, for a good ranking in the search engines of a picture, particularly in Google Images?
- Luca C. M / Bologna, Italy

Why not do both! Here’s what I’d recommend:

1) Give the image a good filename, not more than 50 characters, but include your keyword
2) Give a human readable keyword-inclusive alt tag
3) Surround your image with a contextual paragraph discussing your keyword.

I believe that the surrounding text is really the kicker, it gives the image’s alt and filename context and that’s what the search engines need to try and determine meaning and relevancy, and award you with a good ranking in Google images.