From 598441aa09a2e3b2fa45abb8a758ff76c68f9c9e Mon Sep 17 00:00:00 2001 From: giraffedata Date: Sat, 9 Feb 2019 17:32:42 +0000 Subject: miscellaneous update git-svn-id: http://svn.code.sf.net/p/netpbm/code/userguide@3542 9d0c8265-081b-0410-96cb-a4ca84ce46f8 --- pnmquant.html | 22 +++++++++++++++++++++- 1 file changed, 21 insertions(+), 1 deletion(-) (limited to 'pnmquant.html') diff --git a/pnmquant.html b/pnmquant.html index fe355a3f..61beb2de 100644 --- a/pnmquant.html +++ b/pnmquant.html @@ -2,7 +2,7 @@ Pnmquant User Manual

pnmquant

-Updated: 09 April 2013 +Updated: 09 February 2019
Table Of Contents @@ -41,6 +41,26 @@ color map which is generated from the colors in that same input. The options have the same meaning as in those programs. See their documentation to understand pnmquant. +

You may actually get fewer than ncolors colors in the output because + the method pnmcolormap uses to choose the best set of colors for the + image is not the same as the method pnmremap uses to determine the + best color from the set to represent an individual color. For example, + pnmcolormap may include salmon in the color map as the best + representative of a pink pixel in the input and include coral in the color + map as the best representative of an actual coral pixel in the input. But + pnmremap is free to use any color in the color map to represent that + pink pixel and would find coral is a closer match for pink than salmon and + therefore use coral for pink. pnmremap might not use salmon + for any pixel. + +

This waste of a slot in the color map is a consequence of the approximate + method pnmcolormap uses in order to compute the color map with a + practical amount of computation. + + +

Running pnmcolormap and pnmremap Separately +

It is much faster to call pnmcolormap and pnmremap directly than to run pnmquant. You save the overhead of the Perl interpreter and creating two extra processes. pnmquant is -- cgit 1.4.1