From 2c3fbc4db1aca945072feadb09436cd198e87999 Mon Sep 17 00:00:00 2001 From: giraffedata Date: Wed, 9 Jun 2021 00:31:09 +0000 Subject: miscellaneous update git-svn-id: http://svn.code.sf.net/p/netpbm/code/userguide@4114 9d0c8265-081b-0410-96cb-a4ca84ce46f8 --- pamstack.html | 2 ++ pamtogif.html | 27 ++++++++++++++++++++------- 2 files changed, 22 insertions(+), 7 deletions(-) diff --git a/pamstack.html b/pamstack.html index 52bef06a..df2708d3 100644 --- a/pamstack.html +++ b/pamstack.html @@ -27,6 +27,8 @@ its value with a space instead of =. produces a PAM image as output, consisting of all the planes (channels) of the inputs, stacked in the order specified. +

It can also just change the tuple type of a single PAM image. +

For any one (but not more) of the input files, you may specify "-" to mean Standard Input. If you specify no arguments at all, the input is one file: Standard Input. diff --git a/pamtogif.html b/pamtogif.html index 6d720817..1c1f0ac7 100644 --- a/pamtogif.html +++ b/pamtogif.html @@ -2,7 +2,7 @@ Pamtogif User Manual

pamtogif

-Updated: 05 June 2021 +Updated: 09 June 2021
Table Of Contents @@ -56,11 +56,14 @@ multiple GIF images into an animated GIF, use gifsicle (not part of the Netpbm package). -

pamtogif creates either an original GIF87 format GIF file or -the newer GIF89 format. It creates GIF89 when you request features -that were new with GIF89, to wit the -transparent or --comment options. Otherwise, it creates GIF87. Really old GIF -readers conceivably could not recognize GIF89. +

pamtogif creates either an original GIF87 format GIF file or the + newer GIF89 format. It creates GIF89 when the output needs to have features + that were new with GIF89, to wit transparency or comments. Otherwise, it + creates GIF87. Really old GIF readers conceivably could not recognize + GIF89. The output needs to have transparency when either the input has a + transparency information or you specify the -transparent option. It + needs to have comments when you specify the + -comment option.

pamtogif generates a GIF image with a single image block, which means the image cannot have more than 256 colors in it (it contains a single @@ -69,12 +72,22 @@ more colors than that (ppmhist can tell you), you can use pnmquant to reduce it to 256. Or use the more complex but faster method described under the -mapfile option. -

If your input image is a PAM with transparency information, ppmtogif +

If your input image is a PAM with transparency information, pamtogif uses one entry in the GIF colormap specifically for the transparent pixels, so you can have at most 255 opaque colors. In contrast, if you use the -transparent option, one of the colors from the input becomes transparent, so the limit is still 256. +

pamtogif recognizes transparency information in the input by the + tuple type being RGB_ALPHA, GRAYSCALE_ALPHA, or + BLACKANDWHITE_ALPHA. This is the case for any image that has + transparency information and was created by a Netpbm program that + manipulates visual images. If, on the other hand, you have a PAM generated + some other way, but you know the planes have the same meaning as implied by + these tuple types, you can make pamtogif process the transparency + information by changing the tuple type accordingly before you pass it + to pamtogif. You can use pamstack to change the tuple type. +

pamtogif was new in Netpbm 10.37 (December 2006). In older Netpbm, use ppmtogif. -- cgit 1.4.1