The ImageMod is a collection of extra component, facility, combat, planet, and event images for use with Space Empires IV. Modders can then refer to them in their mods by their names or numbers, thus reducing the need for custom images to be included with every mod. Modders can simply use images from the ImageMod and say "version 17 or later Component Pack and version 11 or later Facility Pack required".
The home of the ImageMod is here:  (note that the preview images are highly outdated)
A mirror site is here: 
To install the ImageMod, simply download the zip or rar files and extract them into the correspondingly named folders unders SE4/Pictures, e.g. Components.zip unzips to SE4/Pictures/Components. You may be prompted to overwrite some files; say yes, as these are just the mini pics, which need to be present for the minis to be available to the game. Do NOT create a separate mod directory for the ImageMod; otherwise other mods will not be able to access its images, defeating the purpose of the whole thing!
When an ImageMod is inevitably created for SE5, it has been resolved by the community that it will not contain copyrighted images, in case of a rerelease of the game, so that the ImageMod for SE5 can be included on the rerelease CD, as this prevented SE4's ImageMod from being included on the Deluxe CD.