New version

Antonio said on 05/10/2018

Pingo it's a great tool but it's very frustrating that with each new version the behaviour of the parameters and the resulting compression ratios changes constantly and for the worst, specially with pngs. Before 0.96z93 I used to compress pngs in 2 pass, the first with -pngfilter and the second pass with -pngcolor and it worked ok, now the second pass with -pngcolor compress nothing at all and the resulting images are much bigger. I think that Pingo should forget the "auto" mode and be much more "deterministic", or maybe make 2 different versions, just my opinion.

cédric (dev) said on 05/11/2018

the behaviour of the parameters

i wrote a manual and examples. i change those according to my tests or feedback: from what i saw here, here or in your own post, there is confusion about how to use pingo

usage

compress pngs in 2 pass, the first with -pngfilter and the second pass with -pngcolor

i do not see how this could work. basically:

  • -pngfilter transforms RGB value according to what the filter will expect including if alpha is 0. the side effect of this is that it could increase the number of colors
  • if you run -pngcolor after this, you actually break this transformation, and you reduce the increased (not original) amount of colors so the quality should be even worse

to get a better quality/size ratio for each sample, i suggest you use -pngfilter=N *or* -pngcolor=N *or* -pngpalette=N and try to decrease N progressively (from the original file, not from the precedent result) to match what you expect (see -pngfilter demo)

results

the resulting compression ratios changes constantly and for the worst, specially with pngs

i guess you did large benchmarks on various files. can you provide your results? here are my trials (in complement, see those posts: better filtering or lossy filter improvements)

auto

Pingo should forget the "auto" mode and be much more "deterministic"

can you be more specific? you probably did some research yourself, so could you share or show your ideas?

comment this