I meant messaging in a more general context. It does not remove that feature at all. Why do you think that two people using the same app or algorithm automatically reveals the presence of a hidden byte array? You just vary the way data is read out of the image using the same password used for encryption. Even if they could recover every single bit using statistics (which they can't) they would have no idea what order to put them in. That's just one way of doing it too. If you put a real math wizard on the case I'm sure they could do even better.

Storage capacity IS a function of the algorithm and the image. That's simply a fact. For example, say we are just bit flipping a 512x512px image and we take up all 8 bits in each color channel in each pixel. That lets us write 512 * 512 * 8 * 3 = 6291456 bits or about 6Mb. ...I can see how it looks like I was talking about real time communication because I said messaging. That was a mistake and honestly I have been playing around with the thought of if/how steganography could be used for chat but that really was not how I meant it to sound. I was thinking about how steganography might be able to make encryption more user friendly.