Here is a pitfall to be avoided in Steganography using low bits of AD converter output. Such converters may be biased in their low bit. If you hid 2,000,000 bits in a digitized image you would probably get from 998,000 to 1,002,000 one bits if you took no precautions. A real digitizer might well be expected to produce more than 1,100,000 one bits or less than 900,000. Falling too close to 50% would be a clue that the data was not the yield of a AD converter. Stuffing a few percent of extra one bits according to a random number generator known to the receiver makes the data look more typical. There may be statictical dependencies with the next more significant bit as well. Some elementary statistics can be done on the yield of a real image scanner to examine this issue.