Image processing, highlighting hidden details

[RobGea]

When going from 8 bits colour depth to 4 bits, you could in principle pick any combination of 4 bits.
I am guessing that you picked the four highest...

Have you tried any of the others?

Hehe, you give me way to much credit, i just put in a call to Python Image Library and it took care of the rest. I guess it would use the 4 highest.
So, no, i did not try any of the other bit combos.