[omoikane]

~500 pixels for every byte seems wasteful, I would have expected just ~8 pixels for a single byte (using just one bit from each pixel).

For comparison, this IOCCC entry can encode ~128 bytes of random binary data in 33000 pixels, or ~16K of ASCII text.

https://www.ioccc.org/years.html#2012_vik

[maxtardiveau2]

Eight pixels ber byte would indeed be more efficient, but the intent of this library was to make the hidden message as discreet as possible, rather than transmit as much hidden data as possible. By modifying only occasional pixels, in an unpredictable pattern (based on a secure hash of the key), my hope was that it would make detection more difficult. Whether I succeeded or not remains to be determined, I suppose.