PIXDIFF(1)

📦
version 7.44.0 · 2 versions
, in nixpkgs unstable

✨ PIXDIFF(1) ✨

okay so this is a page from the BRL-CAD manual set, and the tool is literally called pixdiff — yes bestie, we're diffing .pix files today 💅

🎀 NAME 🎀

pixdiff — highlights the pixel colors that differ between two pix files. it's giving "spot the difference" but make it Unix 🌸

🦋 SYNOPSIS 🦋

pixdiff _file1.pix_ _file2.pix_ > _out.pix_

💖 DESCRIPTION 💖

so pixdiff takes two color pix(5) format images and compares them pixel by pixel, then writes a brand-new pix(5) image to standard output that highlights exactly where they differ. main character energy fr 👑

here's the tea per pixel: if any of the red, green, or blue channels differ, those differing channels get specially marked —

  • bytes that differ by +/-1 are written at intensity 192
  • bytes that differ by more are written at full intensity 255

and where a pixel matches exactly? you get its NTSC black-and-white equivalent at half intensity written instead, which gives you visual context so you can actually locate the differences inside the image. thoughtful icon behavior honestly 🫶

because the comparison is per pixel, pixdiff is independent of image resolution — no cap. but heads up: the two inputs must be the same size in bytes, otherwise the program reports the mismatch and exits. that's the vibe check and it will fail you 😭

either input file may be given as - to read from standard input. oh and output must be redirected — pixdiff flat-out refuses to write a pix(5) stream to a terminal. it's protecting you, bestie 🙈

upon completion, the count of bytes that matched, that were off by 1, and that were off by many is reported on standard error. numbers! love that for us 📊

also go see bwdiff(1), which can also operate on pix(5) files and can produce other kinds of difference output. options, we stan ⭐

🔥 EXAMPLES 🔥

Example 1. Diff two renderings and view the result

pixdiff frame_a.pix frame_b.pix > diff.pix
pix-png -w 512 -n 512 diff.pix > diff.png

this compares two 512x512 renderings, writing a highlight image to diff.pix, then converts it to PNG with pix-png(1) for easy viewing. differing channels glow brightly against a dim grayscale backdrop, making changed regions easy to spot — literally iconic ✨ and the matching/off-by-1/off-by-many byte counts printed on standard error give you a quick quantitative sense of how much changed. slay 💅

🌈 SEE ALSO 🌈

brlcad(1), bwdiff(1), pix-fb(1), pix-png(1), pixstat(1), pix(5)

all the besties in the same friend group 💜

👑 AUTHOR 👑

BRL-CAD Team

This software is Copyright (c) 1989-2026 by the United States Government as represented by U.S. Army Research Laboratory.

🧚 BUG REPORTS 🧚

Reports of bugs or problems should be submitted via electronic mail to devs@brlcad.org — tell them everything, they want the details 📬

okay that's the whole page, no notes 💖 this one's from the BRL-CAD crew, page PIXDIFF(1) of the manual — go forth and diff those pixels, bestie 🌸🦋

📦 where this page comes from