If the distribution of bits in an encrypted stream is indistinguishable from normal image dithering, wouldn't encrypted steganography be hard to detect?

It wouldn't survive any lossy image transformations, though.

Steganography on normal pictures. If the picture is just random pixels then it would not be detectable.

Randomness is something that cryptographers have spent a lot of time studying.

Introducing non-random data into a random data stream is easy to find unless you're very careful about the amounts of data-to-be-hidden and cover-data.

If you encrypt the data first, then you're inserting "random" data as far as analysis goes.

salam