PIXHALVE(1)

💅 PIXHALVE — the pixhalve(1) glow-up

okay bestie, so pixhalve is a little BRL-CAD icon and honestly? it's giving shrink ray ✨ her whole job is to take a color pix file and make it literally half the size in each direction. that's it. that's the gig. 🎀

---

✨ NAME ✨

pixhalve — reduce the resolution of a color pix file by one half 🦋

---

🌸 SYNOPSIS 🌸

pixhalve [-a] [-s squaresize] [-w file_width] [-n file_height] [file.pix] > outfile.pix

---

💖 DESCRIPTION 💖

so pixhalve reads a color pix(5) image and writes out a brand new pix(5) image that's at one half the resolution in each direction — which means the output has one quarter as many pixels. math girlie behavior, we love to see it. 🧮✨

and here's the tea: because this tool is mainly used to prep imagery for NTSC television, it doesn't just yeet pixels. no ma'am. it converts RGB to YUV first, then applies a 3x3 pyramid filter to the luminance (Y) channel and a 5x5 pyramid filter to the chrominance (U and V) channels — and then it downsamples. obsessed with the attention to detail, lowkey. 💅

input is read from file.pix if you give her one, otherwise she takes it from standard input. and the result? always written to standard output. no cap. 🌈

now, the input width must be known so scanlines can be split correctly — that's just how it is, bestie. the width defaults to 512 pixels, and you can set it with -w, or with -s (for square images), or let her detect it automatically from a named file with -a. the image height? doesn't even need to be specified, because input is processed until end of file. main character energy: she just keeps going till there's nothing left. 💀🔥

---

🎀 OPTIONS 🎀

• -a — autosize the input by reading the dimensions right from the named file. she needs a file argument for this one, and it has no effect on piped input (sorry, pipe girlies 🙈). it also disables autosizing... wait, no, it is the autosizing. it's the autosize option, periodt. ✨
• -s squaresize — set both the input width and (nominally) the height to squaresize pixels, for square images. disables autosizing. 🟪
• -w file_width — set the input scanline width to file_width pixels (default 512). disables autosizing. 📏
• -n file_height — accepted for compatibility and to disable autosizing. the height value itself is ignored, because input is consumed until end of file. it's decorative. it's a vibe. it's not doing anything. 💀

---

🦋 EXAMPLES 🦋

Example 1. Downsample a rendered frame for NTSC preview

rt -o frame.pix -w 1024 -n 1024 model.g component &&
pixhalve -s 1024 frame.pix | pix-fb -w 512 -n 512

renders a 1024x1024 image with rt(1), halves it down to 512x512 with that NTSC-tuned YUV filtering, and displays the result on a framebuffer with pix-fb(1). the full pipeline ate and left no crumbs. 🔥

Example 2. Halve a file twice for a quarter-size thumbnail

pixhalve -a big.pix | pixhalve -w 256 > quarter.pix

autosizes the first pass straight from the file header, producing a half-size intermediate, then halves again — so the final image is one quarter of the original width (e.g. 1024 to 256). double halving, double slay. 👑✨

---

🌟 SEE ALSO 🌟

brlcad(1), pixcrop(1), pixrect(1), pixinterp2x(1), pixscale(1), pix-fb(1), pix(5)

---

💜 AUTHOR 💜

BRL-CAD Team — kings, honestly. 🫶

---

🌸 COPYRIGHT 🌸

this software is Copyright (c) 1991-2026 by the United States Government as represented by U.S. Army Research Laboratory. iconic and legally protected. 💅

---

🙈 BUG REPORTS 🙈

reports of bugs or problems should be submitted via electronic mail to devs@brlcad.org — tell them the group chat sent you. 📧💖

---

ok that's the whole page bestie, go forth and halve some pixels ✨🦋

---

BRL-CAD, pixhalve(1) — signed off with love, and dated however the original footer said so 🎀💜 (it's the BRL-CAD release, you already knew that 😌)