pngquant, 2.6.0 (December 2015), by Greg Roelofs, Kornel Lesinski.
   Color profiles are supported via Cocoa. Using libpng 1.6.18.

usage:  pngquant [options] [ncolors] -- pngfile [pngfile ...]
        pngquant [options] [ncolors] - >stdout <stdin

options:
  --force           overwrite existing output files (synonym: -f)
  --skip-if-larger  only save converted files if they're smaller than original
  --output file     destination file path to use instead of --ext (synonym: -o)
  --ext new.png     set custom suffix/extension for output filenames
  --quality min-max don't save below min, use fewer colors below max (0-100)
  --speed N         speed/quality trade-off. 1=slow, 3=default, 11=fast & rough
  --nofs            disable Floyd-Steinberg dithering
  --posterize N     output lower-precision color (e.g. for ARGB4444 output)
  --verbose         print status messages (synonym: -v)

Quantizes one or more 32-bit RGBA PNGs to 8-bit (or smaller) RGBA-palette.
The output filename is the same as the input filename 

***> except that it adds an annoying "-fs8" to the end of the filename.<***

To prevent pngquant from doing that, add an -ext .png to the command.

EXAMPLE: Batch convert an entire folder from 200 ppi to 72 ppi and compress:

pngquant -f --ext .png *.png