NAME

       pngquant — PNG converter and lossy image compressor

SYNOPSIS

       pngquant ⟨options⟩ [ncolors] file [file ...]
       pngquant ⟨options⟩ [ncolors] - <file >file

DESCRIPTION

       pngquant  converts  32-bit  RGBA  PNGs  to  8-bit (or smaller) RGBA-palette PNGs, optionally using Floyd-
       Steinberg dithering.  The output filename is the same as the input name except that it ends in ‘-fs8.png’
       or ‘-or8.png’ (unless the input is stdin, in which case the quantized image  will  go  to  stdout).   The
       default behavior if the output file exists is to skip the conversion; use --force to overwrite.

OPTIONS

       -o out.png, --output out.png
                Writes  converted  file  to  the  given path. When this option is used only single input file is
                allowed.

       --ext new.png
                File extension (suffix) to use for output files instead of the default ‘-fs8.png’ or ‘-or8.png’.

       -f, --force
                Overwrite existing output files.  “--ext .png --force” can be used to  convert  files  in  place
                (which is unsafe).

       --nofs, --ordered
                Disable Floyd-Steinberg dithering.

       --floyd [=N]
                Set dithering level using fractional number between 0 (none) and 1 (full, the default).

       -s N, --speed N
                1  (brute-force) to 11 (fastest). The default is 3.  Speed 10 has 5% lower quality, but is about
                8 times faster than the default. Speed 11 disables dithering and lowers compression level.

       -Q min-max, --quality min-max
                min and max are numbers in range 0 (worst) to 100 (perfect), similar to JPEG.  pngquant will use
                the least amount of colors required to meet or exceed the max quality. If conversion results  in
                quality  below  the  min  quality  the  image  won't be saved (or if outputting to stdin, 24-bit
                original will be output) and pngquant will exit with status code 99.

       --skip-if-larger
                If conversion results in a file larger than the original, the image won't be saved and  pngquant
                will  exit with status code 98.  Additionally, file size gain must be greater than the amount of
                quality lost. If quality drops by 50%, it will expect 50% file size  reduction  to  consider  it
                worthwhile.

       --posterize bits
                Truncate  number  of  least significant bits of color (per channel). Use this when image will be
                output on low-depth displays (e.g. 16-bit RGB).  pngquant will make almost-opaque  pixels  fully
                opaque  and  will  reduce  amount  of  semi-transparent  colors. When this option is enabled the
                default filename suffix is ‘-ie-fs8.png’ / ‘-ie-or8.png’.

       --strip  Remove optional chunks (metadata) from PNG files.

       --transbug
                Workaround for readers that expect fully transparent color to be the last entry in the palette.

       -v, --verbose
                Enable verbose messages  showing  progress  and  information  about  input/output.  Opposite  is
                --quiet.  Errors are output to stderr regardless of this option.

       -V, --version
                Display version on stdout and exit.

       -h, --help
                Display help and exit.

EXAMPLE

       Creating a new image with the number of colors reduced to 64:

             pngquant 64 image.png

       The resulting image will have 64 colors and will be saved as image-fs8.png.

       Overwriting image in-place if it can be reduced without too much quality loss:

             pngquant -f --ext .png --quality 70-95 image.png

AUTHOR

       pngquant   is  developed  by  Kornel  Lesinski  ⟨kornel@pngquant.org⟩  based  on  code  by  Greg  Roelofs
       ⟨newt@pobox.com⟩.

       pngquant homepage: https://pngquant.org.

                                                   2013-02-25                                        pngquant(1)