I noticed that the iron ore mine (factories/erzbergwerk.png) is mostly photographic in the center -- very blurry.
I used some Photoshop effects plus some light touch-up work to re-color and re-balance the center of the image:
http://www.flyingsoft.phatcode.net/papers/extra%20pictures/building-iron%20ore%20mine.png (http://www.flyingsoft.phatcode.net/papers/extra%20pictures/building-iron%20ore%20mine.png)
It's still far from a true pixel-by-pixel work, though, and it does need to be split up into 16 segments...
My modifications are released into the public domain...
Edit: I just edited out a lot of the darker areas in the mine... looks much more cheery now!