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| author | giraffedata <giraffedata@9d0c8265-081b-0410-96cb-a4ca84ce46f8> | 2020-09-09 03:06:54 +0000 |
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| committer | giraffedata <giraffedata@9d0c8265-081b-0410-96cb-a4ca84ce46f8> | 2020-09-09 03:06:54 +0000 |
| commit | 2ab5fffd17f1e979ce63db9212331e51f53811fc (patch) | |
| tree | f4a1e3a2c40c419ace8eb682322de05b889dc7eb /pamarith.html | |
| parent | 412ea2c1c8e8648262b79507a11ba8e141c4efee (diff) | |
| download | netpbm-mirror-2ab5fffd17f1e979ce63db9212331e51f53811fc.tar.gz netpbm-mirror-2ab5fffd17f1e979ce63db9212331e51f53811fc.tar.xz netpbm-mirror-2ab5fffd17f1e979ce63db9212331e51f53811fc.zip | |
miscellaneous update
git-svn-id: http://svn.code.sf.net/p/netpbm/code/userguide@3957 9d0c8265-081b-0410-96cb-a4ca84ce46f8
Diffstat (limited to 'pamarith.html')
| -rw-r--r-- | pamarith.html | 16 |
1 files changed, 15 insertions, 1 deletions
diff --git a/pamarith.html b/pamarith.html index 02c348fa..4bda1c2d 100644 --- a/pamarith.html +++ b/pamarith.html @@ -2,7 +2,7 @@ <html><head><title>Pamarith User Manual</title></head> <body> <h1>pamarith</h1> -Updated: 03 January 2015 +Updated: 09 September 2020 <br> <a href="#index">Table Of Contents</a> @@ -76,6 +76,19 @@ contains the tuple (s) and the right input image contains the tuple (t1,t2,...tN), and the function is f, then the output image contains the tuple (f(s,t1),f(s,t2),...,f(s,tN)). + +<h3 id="pbmoddness">PBM Oddness</h3> + +<p>If you're familiar with the PBM format, you may find <b>pamarith</b>'s +operation on PBM images to be nonintuitive. Because in PBM black is +represented as 1 and white as 0, you might be expecting black minus black +to be white. + +<p>But the PBM format is irrelevant, because <b>pamarith</b> operates on the +numbers found in the PAM equivalent (see above). In a PAM black and white +image, black is 0 and white is 1. So black minus black is black. + + <h3 id="maxval">Maxval</h3> <p>The meanings of the samples with respect to the maxval varies @@ -277,6 +290,7 @@ that made it backward compatible with <b>pnmarith</b>. <li><a href="#synopsis">SYNOPSIS</a> <li><a href="#description">DESCRIPTION</a> <ul> + <li><a href="#pbmoddness">PBM Oddness</a> <li><a href="#maxval">Maxval</a> </ul> <li><a href="#note">NOTE: UNARY FUNCTIONS</a> |