Specially designed for the re compression of PNG captures, MNG animations, ZIP and GZ files, AdvanceCOMP is a development of the AdvanceMAME project and is designed to re compress your collection of ROMs.
This is a particularly good compressor because of the 7-ZIP algorithm it uses for compression. The 7-ZIP standard is a lossless compression standard and is the real stand-out feature of this suite. In particular, if you work with PNG files regularly, you'll find this is one of the best quality re-compression tools you can use. PNG was initially intended as a superior, patent-free replacement of GIF. Unlike other lossless compression schemes, PNG compression does not depend solely on the statistics of the input. However, a good PNG compressor must be able to take informed decisions about the factors that affect the size of the output which is something that AdvanceCOMP does very well.
There are other similar tools that do the same job such as PNGCrush but few do it as efficiently, quickly and with such high quality output as AdvanceCOMP. It's just a shame that it can't re-compress other image formats as well.