PBMREDUCE(1)

✨ pbmreduce — the Pbmreduce User Manual, bestie edition ✨

okay so welcome to Pbmreduce User Manual(1), the glow-up guide 💅 this is a General Commands Manual moment and honestly? iconic.

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🌸 NAME 🌸

pbmreduce — read a PBM image and reduce it N times 🦋

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🎀 SYNOPSIS 🎀

pbmreduce [-floyd|-fs|-threshold] [-value val] [-randomseed=integer] N
[pbmfile]

also, PSA: you can abbreviate any option to its shortest unique prefix. yes fr, go off king 💜

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✨ DESCRIPTION ✨

so first things first: this program is part of Netpbm(1). family reunion 🫶

pbmreduce reads a PBM image as input and reduces it by a factor of N, producing a PBM image as output. in and out, PBM to PBM, no drama.

ngl, pbmreduce duplicates a lot of the functionality of pamditherbw. like you could do something like pamscale | pamditherbw, but pbmreduce is a lot faster. speed. it's giving main character energy ⚡

here's the fun part: you can use pbmreduce to "re-halftone" an image. let's say you have a scanner that only produces black&white, not grayscale, and it does a terrible job of halftoning (most b&w scanners fit this description, unfortunately 😭). one way to fix the halftoning is to scan at the highest possible resolution, say 300 dpi, and then reduce by a factor of three or so using pbmreduce. you can even correct the brightness of an image, by using the -value option. obsessed 🥰

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💖 OPTIONS 💖

so in addition to the options common to all programs based on libnetpbm (most notably -quiet, see Common Options), pbmreduce recognizes the following command line options:

• -threshold — by default, pbmreduce does the halftoning after the reduction via boustrophedonic Floyd-Steinberg error diffusion; but you can use this option to specify simple thresholding instead. this gives better results when reducing line drawings. use it for those ✏️ moments.
• -floyd, -fs — specify the Floyd-Steinberg error diffusion method. this is the default, bestie. it's just built different.
• -value — this option alters the thresholding value for all quantizations. it should be a real number between 0 and 1. above 0.5 means darker images; below 0.5 means lighter. so like, turn the dial, no cap 🎚️
• -randomseed=integer — this is the seed for the random number generator that controls the halftoning. use this to ensure you get the same image on separate invocations. reproducibility slay 🔥

this option was new in Netpbm 10.75 (June 2016). a little baby option, we love her 💕

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🦋 SEE ALSO 🦋

pamenlarge(1), pamscale(1), pamditherbw(1), pbm(1)

go read those too, they're the friend group 🌈

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👑 AUTHOR 👑

Copyright (C) 1988 by Jef Poskanzer. legend behaviour, we respect it 💜

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📚 DOCUMENT SOURCE 📚

This manual page was generated by the Netpbm tool makeman from HTML source. The master documentation is at

http://netpbm.sourceforge.net/doc/pbmreduce.html

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and that's the whole page bestie 🫶 this was netpbm documentation, dated 13 April 2016, and it's still giving Pbmreduce User Manual(1) energy. mwah 💋 go reduce something ✨