Allow mosaic to be created with much less images, why not allow from upwards of just the one image to be used then chop this up to create the segments to compile mosaic from? Back to the drawing board I would say Artensoft

This program create "classic" photomosaic images.
We are planning to create this type of application which create photo collages.

For Artensoft Photo Mosaic Wizard: Early versions limited the number of photos to 150-300. However, the resulting mosaic could appear less impressive than it could be and the initial result could disappoint users. After a series of experiments, we decided to raise the limit to 1500 photos, as this number of photos usually produced very good results. Besides, we uploaded several sets of photos to our site that can be downloaded and added to the program. We may add this option to the program settings in future versions of the product. At the moment, advanced users can manually override this
limitation by editing the configuration file "Documents and Settings\... ...\My Pictures\Artensoft Photo Mosaic Wizard\params\Options.ini" in the notepad:
[MinBase]
Value=1500