svg-color-rinse

Snap the messy near-blacks and near-whites in AI-generated SVG exports (Recraft and friends) to clean anchors, so the files are ready for print work — then optionally minify them with svgo.

A vectorized illustration usually comes back with a dozen "blacks" (#000, #171617, #242228, …) and several "whites" (#fdfcfd, #eae9eb, …). Fixing that by hand in Illustrator, shape by shape, is the tedious part. This tool does it in one pass:

• near-neutral colors at/above 80% tint → true black #000000
• near-neutral colors at/below 10% tint → true white #ffffff
• mid grays are left untouched
• saturated colors are never touched (saturation guard), so a dark navy or deep red can't collapse into black

Tint is 1 − luma/255 (Rec.601). Colors are rewritten wherever they appear — <style> blocks, fill/stroke/stop-color attributes, inline style="", gradient stops — in #rgb, #rrggbb, and rgb() forms. Geometry is never modified (unless you opt into --optimize).

Install

# run without installing
npx svg-color-rinse art.svg

# or install globally
npm install -g svg-color-rinse
svg-color-rinse art.svg

# or from a clone (no install needed unless you want --optimize)
node svg-color-rinse.mjs art.svg

Requires Node 20+. The rinse itself has zero dependencies; svgo is only loaded when you pass --optimize.

Quick start

# one file -> writes art-rinsed.svg alongside it
svg-color-rinse art.svg

# preview what would change, write nothing
svg-color-rinse --dry-run art.svg

Output is a per-file report of every color it touched, with the tint it measured and how many times the color occurred:

art.svg:
  neutral      #171617 (tint  91.2%) -> #000000  [1x]
  neutral    rgb(23, 22, 23) (tint  91.2%) -> #000000  [1x]
  neutral      #242228 (tint  86.2%) -> #000000  [1x]
  neutral      #eae9eb (tint   8.4%) -> #ffffff  [1x]
  neutral      #fdfcfd (tint   1.0%) -> #ffffff  [1x]
  wrote art-rinsed.svg

Batch a whole folder

Directories are processed recursively (previously written *-rinsed.svg files are skipped automatically), and shell globs work as you'd expect:

svg-color-rinse exports/                 # every .svg under exports/, output *-rinsed.svg
svg-color-rinse --in-place exports/      # same, but overwrite the originals
svg-color-rinse batch1/ batch2/ one-off.svg
svg-color-rinse exports/*.svg            # shell glob

Tune the thresholds

# fold in that one 79% gray that just misses the default gate
svg-color-rinse --black 79 art.svg

# stricter white gate, looser neutral detection
svg-color-rinse --white 6 --max-saturation 15 art.svg

Hue gates: the same cleanup for a color family

If the artwork is built on blues (or any hue) instead of blacks, --hue applies the same gate to that family: heavy tints merge into one dark anchor, pale tints wash to white.

# merge heavy blues into the darkest blue already in the file
svg-color-rinse --hue blue art.svg

# pin the anchor yourself and tighten the hue window (default ±30°)
svg-color-rinse --hue 220 --tolerance 25 --dark "#0a1123" art.svg

blue-variant.svg:
  neutral      #0a1123 (tint  93.3%) -> #000000  [1x]
  hue 220°±30   #101c37 (tint  89.2%) -> #0a1123  [1x]
  hue 220°±30   #172951 (tint  84.2%) -> #0a1123  [1x]

Hue names: red, orange, yellow, green, teal/cyan, blue, purple/violet, magenta, pink — or pass degrees 0–360.

Precedence: the neutral gate runs first, so a murky near-gray (saturation ≤ --max-saturation) always counts as black/white territory; the hue gate only claims genuinely colored fills. With no --dark, the hue gate anchors to the darkest color it claims in each file — "make all the heavy blues the same blue".

Quantizing mid-grays

AI vectorizers don't just scatter near-blacks and near-whites — the mid-grays in between are often jittered too, a dozen barely-different fills like #3a3d3b, #3b3e3c, #3c383a where a human designer would have used one. Left alone, each of those becomes its own slightly-different tint on press.

--quantize N snaps every surviving neutral mid-tone (saturation ≤ --max-saturation, tint strictly between --white and --black — the colors the gates leave untouched) onto the nearest of N evenly spaced tint levels: i/(N+1) for i = 1..N. --quantize 4 gives levels at 20%, 40%, 60%, 80% tint; each survivor moves to whichever level it's closest to, output as a neutral gray hex (round(255 × (1 − level)) per channel).

svg-color-rinse --quantize 4 art.svg

art.svg:
  quantize     #3c383a (tint  77.5%) -> #333333  [1x]
  quantize     #3a3d3b (tint  76.5%) -> #333333  [1x]
  quantize     #3b3e3c (tint  76.1%) -> #333333  [1x]

A color already sitting exactly on a level is left alone (no self-replacement row). Quantizing runs after the gates and combines cleanly with --hue and --optimize. It only ever touches neutral mid-tones: colors claimed by a hue gate (saturation above --max-saturation) are never quantized, even if they sit in the same jittered-mid-tone territory — see CLAUDE.md for the reasoning and the workaround.

Optimize with svgo

--optimize runs svgo on each file after rinsing — preset-default, multipass, viewBox preserved (the same settings as process-images):

svg-color-rinse --optimize exports/

art.svg:
  neutral      #171617 (tint  91.2%) -> #000000  [1x]
  ...
  optimized 409,517 -> 381,113 bytes (-6.9%)
  wrote art-rinsed.svg

Savings depend on how tight the export already is: a full-page Illustrator re-export trims ~7%, while rawer generator output compresses much harder (the test fixture drops 64%).

With --optimize, files that needed no color fixes are still optimized and written.

Options

flag	default	meaning
--black <pct>	80	tint at/above which darks snap to the dark anchor
--white <pct>	10	tint at/below which lights wash to #ffffff
--max-saturation <pct>	12	neutral-gate saturation ceiling, (max−min)/255
--hue <name|deg>	off	add a hue gate for that color family
--tolerance <deg>	30	hue window for the hue gate
--dark <#rrggbb>	auto	dark anchor for the hue gate (darkest claimed color if omitted)
--quantize <N>	off	snap surviving neutral mid-grays onto N evenly spaced tint levels
--optimize	off	run svgo (preset-default, multipass, keep viewBox) after rinsing
--in-place	off	overwrite inputs instead of writing *-rinsed.svg
--dry-run	off	report only, write nothing
--help		print usage

The remaining print step

SVG cannot hold CMYK separations or ICC profiles, so a warm-rich-black conversion still happens in a CMYK-capable tool — but on a rinsed file it's a one-shot Illustrator Recolor: map #000000 to your Rich Black spot swatch (e.g. CMYK 40/60/40/100) and the handful of surviving grays fall onto its tints (Illustrator's Dot Gain 20% grayscale conversion lands them at roughly gray tint × 1.08). Record it once as an Action and batch it.

Development

npm install   # svgo, for the --optimize tests
npm test      # node --test against the fixtures in test/

License

MIT