LOWP(1)

📦 version 7.44.0, in nixpkgs unstable

💅 LOWP(1) — the lowp girlies are here

okay so this is lowp, section 1 of the BRL-CAD manual, and bestie, it's giving temporal smoothing icon. let me put you on 💖

✨ NAME ✨

lowp — a 3D low-pass filter that runs across three sequential pix files 🎀

🌸 SYNOPSIS 🌸

lowp file1.pix file2.pix file3.pix [width] > out.pix

that's it. that's the whole vibe check. 🦋

💜 DESCRIPTION 💜

so lowp reads three sequential pix(5) image files that all have identical dimensions, runs a 3D low-pass convolution filter over them, and writes one single smoothed pix(5) image out to standard output. no cap. ✨

the three inputs get treated as consecutive frames in a sequence — think of it like the before, the main character, and the after. a 3x3x3 spatial-temporal kernel gets applied, which lowkey means: each output pixel is the weighted average of

  • the corresponding pixel and its eight neighbors in the middle frame (file2.pix), plus
  • the same neighborhoods in the preceding frame (file1.pix), plus
  • the same neighborhoods in the succeeding frame (file3.pix)

the middle frame gets weighted most heavily, and the kernel weights sum to 84. the math ate, honestly. 🔥

⚠️ heads up: images are assumed to be square. the dimension defaults to 512x512 pixels, and if your images are a different size you gotta supply the optional width argument to set the number of pixels per scanline (which also sets the number of scanlines, since y'know, square).

and the border pixels — that's the first and last scanline, plus the first and last pixel of every scanline — do not get filtered. they're written as black. periodt. 💀

also, lowp refuses to write to a terminal. so you literally have to redirect its output to a file or pipe it into another program. it's not being difficult, it's just boundaries. 🙈

🎀 OPTIONS 🎀

  • file1.pix file2.pix file3.pix — the three input pix(5) files, handed over as a sequence of frames. the middle file is the one that actually gets smoothed (she's the main character 👑).
  • width — width and height, in pixels, of the (square) input images. defaults to 512.

🌈 EXAMPLES 🌈

Example 1. Temporally smoothing a rendered animation frame

rt -s 1024 -o frame1.pix model.g region &&
rt -s 1024 -o frame2.pix model.g region &&
rt -s 1024 -o frame3.pix model.g region
lowp frame1.pix frame2.pix frame3.pix 1024 > smoothed.pix
pix-png -s 1024 smoothed.pix > smoothed.png

so what's happening here: we render three 1024x1024 frames with rt(1), then blend them into a smoothed middle frame to knock down per-frame noise and aliasing, then convert the result to PNG with pix-png(1). the glow-up is real. ⭐

🦋 SEE ALSO 🦋

brlcad(1), rt(1), pixfilter(1), pix3filter(1), pix-png(1), pix(5)

iykyk 💅

💖 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

okay that's the whole page, bestie — brought to you by BRL-CAD, LOWP(1), and the year range 1989-2026. go smooth something. 💜✨

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