This is what I remember and it was a really classic example even in Schneiers book. But yeah easy overlay method was just picking a picture with the number of p

This is what I remember and it was a really classic example even in Schneiers book. But yeah easy overlay method was just picking a picture with the number of pixels >= number of encrypted message bits. Make the LSB of each pixel equal to a bit value of the message. EZPZ lemon squeezy and it doesn't affect the image visually. If your message was encrypted well then also the bits would appear randomly so no one would be able to be certain a message was contained as you said.