Photoshop or other BMP software - provinces generator for PDX studio Game

I would like to ask everyone here If it's possible to make generator that would automatically generate about 15 000 provinces in any graphical software that can save into 24 bitmap.

The hard stuff is, each one and single province needs to have different RGB values, preferably blue hues for water pronvices and other colors for land ones and it would be nice if land pronvices close to each other had very different colours (like red and purple or green). And each province have from 10x15px to 120x120px (about, I think it can be somewhat bigger) and map is 5600px x 2000px. Water provinces can be bigger, but land should be smaller for more tactical opportunities.

The user could select where land and where water provices should be.

Is this possible? How hard would that be? Are there ready solutions?

I don't know, but that would help a lot of folks with map modding for pdx games (especially HoI IV)