OK, heres a little lossless bitmap compression test i've made.
It's about the best or most popular (IMO) programs for compressing images losslessy. Today as HDD space is plenty so lossy compression is sometimes superfluous. Some of us have access to unaltered digital content (e.g. RAW digtal camera files) which needs to be archived and stored as original.
7-zip v4.45 beta - I decided to be simple and just used default settings
PNG - for this I chose Irfanview 4, compression level 9 (max)
Optimized PNG -automated optimizing script (credit goes to JensRex from HA)
JLS (loco) - HP free implementation, default settings
CoBALP- I used the version provided by Stephan Bush, all default with and without color conversion
Images - I tried to pick various images with different complexity and dimensions and origin.
comments will come later