A TUI RGB color picker. Two slots (foreground + background), R/G/B and H/S/V sliders, hex input, live sample-text preview, WCAG contrast indicator. Pure ANSI 24-bit truecolor — no kitty graphics dependency, works in any modern terminal.

Member of the Fe₂O₃ Rust terminal suite (landing page).

• Two color slots. Edit foreground and background side-by-side, Tab to swap which one is active.
• RGB and HSV at the same time. Six sliders share one underlying color: nudge the hue and the R/G/B values move with it; nudge red and the hue/saturation/value follow. Pick whichever axis fits the job.
• Hex input. Press #, type six hex digits, Enter.
• Live sample text. A multi-line sample area renders the current FG-on-BG against realistic content (heading, code, comments, body prose, special characters), so you immediately see whether the pair is readable.
• WCAG contrast. The contrast ratio between FG and BG is shown with a level marker (AAA ≥ 7 / AA ≥ 4.5 / AA· ≥ 3 / ✗ low), so theme work doesn't ship unreadable pairs.
• Pipe-friendly output. On quit, the chosen colors are printed to stdout in your chosen format (hex / rgb / hsv / all). Use it to drive sed against a config file, or capture a single hex with prism --pick.
• Tiny. ~500 KB stripped binary. ~5 MB resident. No async runtime, no allocator hot path, no work between keystrokes.

PATH="/usr/bin:$PATH" cargo build --release
ln -sf "$(pwd)/target/release/prism" ~/bin/prism

prism                    # interactive (pair mode, prints both slots)
prism --pick             # pick a single color (the FG slot)
prism --pair             # explicit pair mode (the default)
prism --hex              # output as #rrggbb (default)
prism --rgb              # output as rgb(R, G, B)
prism --hsv              # output as hsv(H°, S%, V%)
prism --all              # output all three formats
prism #f74c00            # preload FG with this hex
prism #f74c00 #0a0a14    # preload both FG and BG

On quit, the chosen colors print to stdout one per line, prefixed with the slot name:

$ prism --pick
color=#f74c00

$ prism --pair --rgb
fg=rgb(247, 76, 0)
bg=rgb(10, 10, 20)

This makes prism easy to script against:

# Update glassrc fg color
hex=$(prism --pick #$(grep '^fg=' ~/.glassrc | cut -d# -f2) | cut -d= -f2)
sed -i "s/^fg=.*/fg=$hex/" ~/.glassrc

• ~500 KB stripped binary
• ~5 MB resident
• Pure ANSI 24-bit truecolor, no kitty graphics dependency
• No subprocess spawns once running, no polling

Works in any terminal that handles 24-bit truecolor SGR escapes:

• glass, kitty, wezterm, foot, alacritty, st, xterm (with 256 + Tc), iTerm2, Apple Terminal (modern)
• tmux: requires set -g default-terminal "tmux-256color" and set -ag terminal-overrides ",xterm-256color:RGB" so SGR 38;2/48;2 passes through

A prism splits white light into its component colors. The picker splits a single hex value into its R / G / B and H / S / V channels so you can dial each axis independently while watching the result on real text.

Unlicense (public domain). Borrow or steal whatever you want.