Today I Searched joomla template different header on pages for a good solution to display a different header image for a couple of pages for a joomla website. I found this page http://www.alledia.com/blog/design/different-header-images-on-different-pages/ that referred to a module that could be installed, Header Image, that would do exactly what i wanted.
Header Image is a flexible module able to display context related images, media or other files. Based on the context of the current displayed Joomla Content, that is the ID’s of section, category, item and content, the module selects a corresponding image or media file to display.
Header Image was removed from free joomla repository and is only available from their website. The non-commercial version is free and the commercial version is 39 euros.
It was super easy to get up and running. Just download Header Image from there website and install it using the extension manager. Then add the extension to the position you want your images to display at in your template. Set up your default folder with the images you want to display and then name with according to your rules. For example I wanted my images to display according to there article ID so i named my images CI55.gif where 55 is the article id. I also set a default image that will display if no matches are found.
This module is a lot more powerful than just displaying a single image on a single page. It can also do slide shows and you can get more advanced in your image naming for a more dynamic headers based on section, category and content.