andeecollardandClaude Opus 5.5
1e06c82800
The Automatic palette counts flat art's colours by area (a colour needs about 1% of the picture, 0.5% at Colors 100) and fits that count with median cut and area-weighted k-means. A stem, a highlight, or a near white beside a pale background (within 24 levels, so in one box) was averaged into a large neighbour; mixed-colour merging and Noise could then remove what was left. On the flat route only, after the count is fitted, rare_colours finds the colours too rare or too close for it and keeps those that are distinct (at least 2.5 in Oklab x 100 from every palette colour and from the main colour each stands for), flat (mostly one histogram bin) and drawn (a 4-connected region of their own unblended pixels of at least 8 pixels, or three of at least 4); a colour lying between two others, as anti-aliasing mixes them, must also have an inside. At most six, largest region first. They stay fixed while the other colours are refitted around them; merge_mixed leaves them alone; denoise_keeping keeps their regions of 4 pixels or more whatever Noise is (smaller specks still go). Full Tone, Limited and Automatic's continuous-tone route are unchanged, and denoise without kept labels is as before. Methods cited in the code: median cut (Heckbert 1982), k-means (Lloyd 1982), Oklab (Ottosson 2020), salient-colour preservation (Fukuda et al. 2019, doi:10.1117/12.2521607). The rule and its numbers are VectorCraft's own; Adobe does not document how its palettes are chosen. Tests (code-drawn): a rare stem or patch over 2-8 flat colours, hard and anti-aliased at 1x and 2x; near-white highlights on #FFF4E0 kept and still paths at Noise 16; a 3 px #909090 stem on #808080; scattered single pixels of the same areas add no colour; denoise_keeping at Noise 0-32. Measured on 66 synthetic flat logos (22 designs x hard 1x, anti-aliased 1x and 2x; local inputs): every key colour and no spurious one in 66 (was 39); missing key colours 0 (was 43), spurious 0 (was 2), merged pairs 0 (was 46); rendered dE00 0.348 -> 0.138. Four public-domain scan crops take the continuous-tone route and are unchanged. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_018tBcdwNhptqtmX32JCGFzB
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Adjusting an Image Trace
Select a placed raster image, then choose Image Trace or a preset from its arrow in Properties or the Control bar. The original image stays inside the tracing object so that subsequent adjustments always use the original pixels.
To adjust the result, select the tracing object and click Image Trace in Properties or the image icon in the Control bar: the Image Trace panel opens with Advanced expanded. An existing floating or docked panel is activated in its current location. Opening the controls does not add a document undo step.
| Control | Range | Effect |
|---|---|---|
| Threshold (Black and White) | 0–255 | Higher values include lighter pixels as black ink. |
| Paths | 0–100% | Higher values fit outlines more closely to the image. |
| Corners | 0–100% | Higher values preserve more sharp turns. |
| Noise | 1–100 px | Suppresses small connected regions; higher values remove more small details. |
| Method | Abutting / Overlapping | Chooses shared boundaries or stacked overlapping paths. |
| Create | Fills / Strokes | Creates filled areas, stroked lines, or both. |
| Ignore Color | Color picker | Leaves out the selected color (white by default). |
Sliders apply on release, and their numeric fields can be edited directly. Each committed adjustment re-traces the selected object as one undo step and changes the preset to Custom. While dragging, the preset and Enhanced row stay in place until release so the slider retains its active interaction. Committed settings are synchronized immediately, so Undo also restores the panel values before its next frame. View can show the source image, the result, outlines, or combinations without re-tracing. Use Expand when finished to turn the result into ordinary editable vector objects; after expanding, the tracing settings are no longer available. Release restores the source.
Auto Color (the Automatic palette) counts flat art's colours by area, and also keeps colours too rare for that count when they are distinct and drawn as regions of their own (a stem, a highlight, a white beside a cream), at most six; scattered specks of a colour add none. Adobe does not document how its own palettes are chosen; this is VectorCraft's own method (see image-trace-quality.md).
Large images. An image of more than 1500 pixels on a side is traced as any other, only more
slowly, and the trace says so: imageTrace.make returns the note in warnings and the status bar
shows it (the results optimization
page describes the same warning for images over 1500 px). An image of more than 64 megapixels (up to
192) is traced from a copy scaled down to 64 megapixels, and the trace says that too. A trace that would
make more than 8,000,000 anchor points (2,000,000 on the web) is refused to protect memory, with advice:
raise Noise, lower Paths or Colors, or pick a lower-fidelity preset. A trace keeps
about 90 bytes an anchor; a 4000 × 3000 photo at High Fidelity Photo makes about 1.9 million.
These controls use VectorCraft's existing tracing algorithm. Parameter effects follow its
implementation; they do not claim pixel-identical results with another application.
The terminology and general control behavior are described in the
public Image Trace panel documentation.
Regression coverage: crates/ui-egui/src/panels/image_trace.rs tests opening the panel,
a quick trace leaving it as it was, repeated opening, floating ownership, slider commits, visible threshold
changes, undo, and the Properties entry point. Tracer tests live in crates/trace/src/tests.rs.