FBCMAP(1)

💅 FBCMAP(1) — the BRL-CAD glow-up for your framebuffer

okay so bestie, buckle up: fbcmap is that one little tool from BRL-CAD that slaps a built-in color map onto your framebuffer. iconic behavior, honestly.

✨ NAME ✨

fbcmap — load a built-in color map onto a framebuffer 🎀

🌸 SYNOPSIS 🌸

fbcmap [-h] [-F framebuffer] [-{sS} squarescrsize] [-{wW} scr_width] [-{nN} scr_height] [map_number]

💖 DESCRIPTION 💖

So basically fbcmap writes one of several built-in color maps to a framebuffer. That's it, that's the whole gig. 💅

When you run it with no map_number argument, or with a map_number of 0, it loads the standard linear (identity) color map. Every other map number picks a different mapping — think photographic negative, film correction, gamma correction, or solid calibration fields. little menu of vibes, basically. ✨

⚠️ heads up bestie: fbcmap is deprecated and scheduled for removal. for general gamma correction use fbgamma(1) instead. no cap, go switch. 😭

🦋 OPTIONS 🦋

• -h — print a usage summary that lists all the available maps, then exit. the "what are my options" button. 💁‍♀️
• -F framebuffer — pick the framebuffer device. if you don't give one, the FB_FILE environment variable is used (peep brlcad(1)); and if that's unset too, the default device for your system gets used. defaults on defaults, fr fr. 🫶
• -s squarescrsize — set both the width and height of the framebuffer to squarescrsize pixels. square era. 🎀
• -S squarescrsize — literally the same as -s. same energy, different capital. ✨
• -w scr_width — set the framebuffer display width to scr_width pixels.
• -W scr_width — same as -w, capital edition. 💅
• -n scr_height — set the framebuffer display height to scr_height pixels.
• -N scr_height — same as -n. lowercase walked so uppercase could run. 🌈

If you give no size options at all, the requested framebuffer size is just the default for the selected device — typically 512x512 pixels. 🖼️

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🎨 the map_number argument (the fun part)

The optional map_number argument selects which color map gets loaded. main character energy, each and every one:

• 0 — linear (identity) color map. this is the default. ✨
• 1 — reverse-linear (photographic negative) map. spooky season. 🙈
• 2 — corrected for Polaroid 809/891 print film. vintage core. 📸
• 3 — linear map, but with the low 100 entries set to black. moody lighting.
• 4 — middle range amplified (shifted up by 64) to boost dim pictures; entry 0 stays black and the top entries clamp to full intensity. glow-up for your dark pics. 🔥
• 5 — the gamma-correcting map from the University of Utah Alpha_1 project. academic slay. 👑
• 6 — color deltas: mostly black, with full-intensity colors at multiples of 32 — white 0, magenta 32, red 64, yellow 96, green 128, cyan 160, blue 192. a whole rainbow in there. 🌈
• 8 — Ikcmap 8 false-color map. 🧚
• 9 — Ikcmap 9 false-color map. 🧚
• 10 — solid black. 🖤
• 11 — solid white. 🤍
• 12 — 18% neutral grey. the classic. 🌫️

Maps 10 through 12 are useful for adjusting a camera to a uniform field without disturbing image memory. lowkey a lifehack, ngl. 💡

⭐ EXAMPLES ⭐

Example 1. Display a negative of an existing image

pix-fb -F /dev/fb0 moss.pix
fbcmap -F /dev/fb0 1

Load an image onto a framebuffer with pix-fb(1), then load map 1 so the displayed pixels appear as a photographic negative — and the best part? it does this without altering the stored pixel values. your file is untouched, only the vibes changed. 💅 Loading map 0 afterward restores normal appearance. 🎀

Example 2. Calibrate against a uniform 18% grey field

fbcmap -s 1024 12

Open (or size) the framebuffer to 1024x1024 and remap every pixel to 18% neutral grey — a common reference value when you're adjusting a camera or monitor. calibration but make it cute. 🩶

🔍 SEE ALSO 🔍

brlcad(1), fbgamma(1), pix-fb(1), fbclear(1) — go read them, they're all part of the family. 🫶

👑 AUTHOR 👑

BRL-CAD Team 💜

📜 COPYRIGHT 📜

This software is Copyright (c) 1989-2026 by the United States Government as represented by U.S. Army Research Laboratory. yes ma'am, official. 🎀

🐛 BUG REPORTS 🐛

Reports of bugs or problems should be submitted via electronic mail to devs@brlcad.org. don't be shy, they want to hear it. 💌

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and that's the whole page bestie, from the BRL-CAD squad — mwah, go load a color map, ily 💖✨🦋