>>109
If you could make any signal appear to be random then I think you would be set. Maybe something like:
000 -> 0110100010011
001 -> 0001001001110
010 -> 1100100001110
011 -> 1001010011001
100 -> 0101011010011
101 -> 0010011110101
110 -> 0110100100011
111 -> 0010111101001
You know, just a function that takes a number and encodes it as a bit stream where the probability of the signal being one or zero is one half, and other properties of random signals are satisfied as well as possible.
Then you could use this with that one stenagraphy algorithm proposed by anonymous-kun where you encode a bit stream in the least significant bit of the color channels based upon whether it is consistent or not with another bit.