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diff --git a/pamdepth.html b/pamdepth.html index 56bbda07..98cdabbe 100644 --- a/pamdepth.html +++ b/pamdepth.html @@ -2,7 +2,7 @@ <html><head><title>Pamdepth User Manual</title></head> <body> <h1>pamdepth</h1> -Updated: 19 December 2013 +Updated: 26 August 2020 <br> <a href="#index">Table Of Contents</a> @@ -44,6 +44,25 @@ rely on that. If you specify a <i>newmaxval</i> less than 256, the resulting file should be readable by any program that worked with PNM files before April 2000. +<h3 id="output_format">Output Format</h3> + +<p>The output format (PBM, etc.) and, in the case of PAM, tuple type, of the +output is usually the same as the input. + +<p>However, changing the depth of a black and white image does not make +sense, except to turn it into a grayscale image, so if the input is a black +and white image, <b>pamdepth</b> makes the output grayscale. To be more +precise, if the input is a PBM image, the output is PGM, and if the input +is a PAM with tuple type BLACK_AND_WHITE or BLACK_AND_WHITE_ALPHA, the +output is a PAM with tuple type GRAYSCALE or GRAYSCALE_ALPHA, respectively. + +<p>This conversion happens even if the new maxval is 1. + +<p>Before Netpbm 10.92 (September 2020), <b>pamdepth</b> failed if the input +was PAM with a black and white tuple type and the new maxval was anything but +1. But it always promoted PBM to PGM. + + <h2 id="options">OPTIONS</h2> <p>There are no command line options defined specifically |