1\" Process this file with 2.\" groff -man -Tascii foo.1 3.\" 4.TH PNGNQ 1 "MAY 2009" Linux "User Manuals" 5.SH NAME 6pngnq \- quantize png images 7.SH SYNOPSIS 8.B pngnq [-vfhV][-s 9.I sample_factor 10.B ][-Q 11.I dither 12.B ][-g 13.I gamma 14.B ][-e 15.I extension 16.B ][-d 17.I dir 18.B ][-n 19.I colors 20.B ][ 21.I inputfiles 22.B ] 23.SH DESCRIPTION 24.B pngnq 25Quantizes a 32-bit RGBA PNG image to an 8 bit RGBA palette PNG 26using the neuquant algorithm. The output file name is the 27input file name extended with "-nq8.png" or a specified extension. 28 29.SH OPTIONS 30.IP -v 31Verbose mode. Prints status messages. 32.IP -f 33Force ovewriting of files. 34.IP "-s sample factor" 35Sample factor. The neuquant algorithm samples pixels stepping by this value. 36The default value of 3 gives good results. Higher values sample less 37of the image pixels and thus are faster but less accurate. A factor of 1 samples 38every image pixel. 39.IP "-n colors" 40Specifies the number of colors to quantize to. Defaults to 256 which is the maximum. 41The minimum here is 2. 42.IP "-Q dither" 43Choose a dithering method: n = no dither (default), f = Floyd Steinberg dithering. 44.IP "-g gamma" 45Set the image gamma correction. If not present, uses the png file's gamma or defaults to 1.0. 46.IP "-e extension" 47Specifies the new filename extension. Defaults to "-nq8.png". 48Pngnq drops .png from the original filenames. If you set the argument of the -e option 49to .png and choose the -f option the input file will be overwritten. 50.IP "-d dir" 51Tells pngnq to put output files in a directory other than the one the input files 52are in. 53.IP "input files" 54The png files to be processed. Defaults to standard input if not specified. 55If standard input is being processed the output is sent to standard output. 56.IP -h 57Print program help. 58.IP -V 59Print version number and library versions. 60 61.SH BUGS 62Does not deal correctly with greyscale alpha images with low bit depths, but these wont benefit from quantizing. 63 64.SH AUTHOR 65Stuart Coyle <stuart.coyle@gmail.com> 66.SH "SEE ALSO" 67.BR png(5) 68