SVG Brand-Tint Studio

Recolour any SVG to a brand palette — theme-aware — and get a copy-paste CSS filter you can bake into an app. Also vectorises rasters (PNG/JPG → SVG) so a flat-image logo or a screenshot becomes an editable, recolourable SVG. One zero-dependency HTML file served by a ~90-line Node server. Nothing uploads — pixels are read in a local <canvas>.

Extracted from a real job: taming a CloudCraft AWS-diagram export into a house brand for an app's hosting page. It generalises to any third-party SVG export (draw.io, Figma, Mermaid, Excalidraw, icon sets) and any raster you need as vector.

When to reach for it

• A diagram/icon/logo export is the wrong colours and has hundreds of inline fill/stroke values you don't want to hand-edit.
• You want a duotone / tri-tone brand treatment and a light + dark variant from one palette swap.
• You have a PNG/JPG and need clean vector paths (threshold, posterised, or colour-quantised — an in-browser Image-Trace).
• You need the exact CSS filter: line (and a React snippet) to bake a theme-aware tint into a real page.

This is a skill, not a rule: it carries the operational knowledge (the colour math, the trace pipeline, the bake pattern) plus the working tool. For one-line "always do X" guidance there's no rule here — the value is the studio + the reference.

Run the studio

node skills/svg-brand-tint-ops/scripts/server.mjs        # → http://localhost:4322
# PORT=8080 node …/server.mjs      choose a port
# node …/server.mjs --root ./icons  serve your own folder of SVGs/PNGs
# node …/server.mjs --help          usage + exit codes

It serves the sibling assets/ (the studio + a generic sample.svg). Open the URL, then drop an SVG or PNG on the canvas (or use the Source panel's sample buttons). The left rail is accordion sections; the right is a scalable, pan/zoom viewport with a live readout of the exact filter: line and ramp hex.

What the panels do — Source (load SVG/PNG/JPG, drop, paste, samples) · Image Trace (raster → vector: B&W / Steps / Color, detail, smoothing, despeckle) · Tone Map (the N-stop brand ramp + presets + "palette from image") · Photographic (saturate/contrast/brightness/hue/sepia/blur/drop-shadow) · Strokes & Fills (outline-only, fill-only, stroke width/colour) · Typography (curated Google Fonts on the SVG's <text>, weight, size scale, tracking) · Geometry (rotate/flip/scale, strip fixed size) · Canvas (checker/solid/ light/dark, padding, grid) · Inspect (hover to highlight any element with its tag/id/class/colours) · Export (copy CSS / baked SVG / tokens / React snippet; download SVG or PNG @1–4×). Split (top bar) is a before/after divider.

How the recolour works (tri-tone)

Three stacked stages — the first two are one SVG <filter>, the third is CSS:

1. feColorMatrix type="saturate" values="0" → collapse the source to a grey ramp.
2. feComponentTransfer → remap that ramp per channel to the brand stops via tableValues (lines → ink, mid → accent, faces → canvas).
3. filter: url(#tonemap) saturate(1.55) … → CSS tune on top.

Two stops = duotone (often washed); a third accent midstop = tri-tone that reads as designed. Custom stop positions are handled by resampling the ramp to a fixed table. Full derivation, N-stop math, and the sRGB vs linearRGB note: references/tri-tone-and-trace.md.

How the vectoriser works (PNG → SVG)

A from-scratch, accuracy-tuned engine (assets/trace-core.mjs, shared by the tool and the headless CLI): 2× supersample → alpha-aware segment into layers (threshold / posterise / median-cut → k-means-refined → merged colour) → interpolated sub-pixel iso-contours (fill-rule="evenodd" cuts holes) → closed-ring Douglas–Peucker → corner-split + Schneider least-squares Bézier fit (fairs out staircase noise into clean curves; straight runs and letter corners stay razor-sharp) → despeckle. Benchmarked on 24 real logos (RMSE ≈27→11.5, edge-F1 0.66→0.86) it reproduces bold/geometric/coloured marks near-perfectly (thin small text stays readable). It's one continuous move: PNG → trace → SVG → brand-tint. Algorithm + tuning knobs: references/tri-tone-and-trace.md §2.

Trace from the command line (needs sharp to decode; the browser tool needs nothing):

node skills/svg-brand-tint-ops/scripts/trace.mjs logo.png logo.svg --colors 6
node skills/svg-brand-tint-ops/scripts/trace.mjs --help    # flags + exit codes

Baking the result into an app

Render the SVG inline (an <img> sandboxes fonts + var() tokens + document filters). Because filter primitives can't read CSS variables, read your theme tokens with getComputedStyle(el).getPropertyValue('--ink') and write the feFunc* tableValues in JS — rebuild on theme change so light/dark re-tints for free. Strip the root width/height (keep viewBox) so it scales. Apply filter: url(#id) saturate(…). The studio's Export → React snippet emits this pre-filled; the full pattern + gotchas ledger is in references/tri-tone-and-trace.md §3–4.

Resources

Path	What
scripts/server.mjs	Zero-dep Node static server. node scripts/server.mjs --help for flags (--root, --port, exit codes). Serves assets/.
scripts/trace.mjs	Headless PNG/JPG → SVG tracer over the shared engine. --help for options + exit codes. Needs sharp to decode (browser tool doesn't).
assets/trace-core.mjs	The canonical, dependency-free trace engine (traceImage). Same code the tool runs inline; imported by the CLI. DEFAULTS at the top are the tuning knobs.
assets/index.html	The studio — the whole tool in one self-contained file (kept classic-script so the file:// preview works). Editable PRESETS and FONTS maps near the top of the <script>; brand palettes are examples only.
assets/sample.svg	Generic (brand-agnostic) diagram that auto-loads for a first-run demo.
references/tri-tone-and-trace.md	The colour math, the trace algorithm, the theme-aware bake pattern, and a gotchas ledger.

Tenant-agnostic: every shipped palette (petrol, mono, blueprint, …) is an example. Swap the PRESETS map for your own tokens — nothing here is bound to a brand.