As I said: it decompresses with 2GB/second. How much slower would the
startup
be for a 22MB image?
(The idea would be to only do that for small images)

To quote https://code.google.com/p/lz4/

������. extremely fast decoder, with speed in multiple GB/s per core,
typically reaching RAM speed limits on multi-core systems."

Marcus

Are you sure it's worth the added complexity of a self-decoding image in lz4 (as well as a dependency on yet one more external item)?