image disable via category

Sounds like your theme has a category.php page?
See http://codex.wordpress.org/Template_Hierarchy#Category_Page

If it does, have a look at The_Loop in it and see if it is using the_excerpt() instead of the_content(). You can just change it to use the_content().

Or, if you still want excerpts, but want pictures too, look at using this plugin instead http://guff.szub.net/2005/02/26/the-excerpt-reloaded/

Alas, I’m not in a position to have the time to dive into your theme, but if you don’t have a category.php, check out your index.php and look for the is_category() tag: http://codex.wordpress.org/Conditional_Tags#A_Category_Page
and the_excerpt.