Quality pass: faithful color illustrations + smooth curves + small-feature fidelity (v1.0→v1.3)#43
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Quality pass iteration 1, from testing on real illustrations: - preprocess is now mode-aware (#35): color illustrations are no longer pre-quantized to 16 / over-denoised, so small features (faces, eyes) survive and dark fills (outlines, hoodies) are kept. - solid backgrounds are preserved (#34): remove_background defaults off for color and binary (a solid background is content, not noise). - verify no longer starts color-starved (#36): first pass traces at full color_precision instead of ramping up from 1. - root cause of vanishing dark regions: the illustration preset now uses hierarchical=cutout. postprocess regroups paths by fill, which reordered a stacked SVG and let light layers paint over dark ones. Cutout regions don't overlap, so regrouping is order-safe (raw trace was already faithful at sim~0.98; postprocess was destroying it). Real-image results: shiba 0.92->0.96 (face/hoodie/bg restored), snowman 0.86->0.97 (subject restored), doodle 0.95->0.97. Corpus goldens recalibrated upward to lock the gains; no similarity regressions. Photo path/byte budgets widened (gradients trace richer now) — bloat reduction tracked in #38. Closes #34, closes #35, closes #36 Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Full-resolution inspection revealed three artifacts the downscaled previews hid: jagged outlines, white cracks between regions, and shattered fills. Root cause of the first two: postprocess grouped paths by fill color and emitted the groups in sorted-hex order, which reorders the tracer's stacked paint order (later = on top). Black/dark fills got painted under lighter ones and were covered — the earlier cutout workaround then traded the vanishing for inter- region gaps and rough edges. Fix: group only *consecutive* same-fill paths (order-preserving) and keep the illustration preset on hierarchical=stacked. Paint order is now exact, matching the raw tracer output (sim ~0.97 on doodle/shiba/snowman, gaps and jaggies gone). Color-variation 'shattering' on painterly inputs (lettering, watercolor) is a separate root cause (color flattening) tracked in #38. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Color-variation-heavy art (painterly, shaded lettering) traced into many small faceted regions — a 'shattered glass' look — and bloated the output. Add a bilateral flatten step (skimage denoise_bilateral, sigma_color=0.04) to the color preprocess: it smooths gradients/texture *within* regions while preserving edges, so those areas trace into clean flat color instead of facets. Mild enough that flat art is untouched (snowman/doodle similarity within ~0.5%) while painterly inputs improve and shrink a lot: - watercolor: 4808->2689 paths, 960KB->402KB, similarity 0.79->0.80 - doodle: 336->26 paths, 45KB->8KB - lettering: smoother letters, no facets Addresses #38 (bloat) and the shattering artifact. Corpus goldens recalibrated; no similarity regressions. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Adds src/svgsmith/smooth.py: corner- and straight-edge-preserving curve refitting
that removes the pixel-boundary wobble vtracer leaves on contours. Splits each
closed contour at corners, keeps straight edges crisp (stripes/geometry), and
Gaussian-smooths + Catmull-Rom-refits genuinely-curved arcs. Wired into the
pipeline behind ConvertOptions.smooth / --smooth, default OFF.
Visually a clear win on outlines (doodle, snowman body) while scarf stripes stay
crisp. Default off because the Catmull-Rom emit is not yet compact (3-8x larger);
v1.2 will add least-squares Bezier fitting for smooth AND compact output.
Versioned test outputs under z-design/SVGSmith_Convert/output/{v1.0,v1.1}/ with
VERSIONS.md for tracking. (XML parsing uses stdlib xml.etree to match the existing
codebase; input is always our own freshly-generated SVG, not external — defusedxml
hardening tracked separately.)
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
…act) Replaces v1.1's dense per-point Catmull-Rom with Schneider 1990 recursive least-squares cubic fitting (generate-bezier -> Newton-Raphson reparameterize -> split-at-max-error). Node count is governed by a canvas-relative fit-error tolerance, so contours are smooth AND sparse instead of bloated. vs the gap analysis target (perfectvector): doodle 79% curves at 10KB (was v1.0 8KB jagged / v1.1 67KB dense); snowman crisp stripes + smooth body at 31KB. Corner detection now runs on the raw resample (before per-arc denoise) so stripe/rectangle vertices are preserved, not rounded. Smoothing is now DEFAULT ON for color mode, SSIM-guarded: the smoothed result is kept only if it costs < 0.06 SSIM vs un-smoothed (a larger drop means a lost feature -> fall back). Thresholds are canvas-relative (viewBox-diagonal ratios). Corpus goldens recalibrated for the small expected SSIM cost; suite green. Addresses #39 (P0a). Palette reduction (#41) next. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Drives color illustrations toward a small, clean flat palette like professional output, without the fixed-K risk of crushing genuinely rich art: - postprocess palette consolidation now uses perceptual CIE76 deltaE in LAB (was raw RGB euclidean), so visually near-identical tints (the many close skin tones a tracer emits) collapse while distinct hues are kept. Threshold 14 deltaE. - illustration preset color_precision 8 -> 6: fewer, flatter regions up front. Adaptive result (vs perfectvector's 7 colors on the Shiba): shiba 24->7 colors, 236->95 paths, 50KB->24.5KB; doodle 2 colors; snowman 9 — while rich art stays rich (vector 21, lettering 30, watercolor 25), not crushed. Visual fidelity holds (colors faithful). Corpus goldens recalibrated; suite green, no SSIM regressions. With P0a (Schneider smoothing) this brings the Shiba to perfectvector-comparable quality. Addresses #41. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Deep-dive (multi-agent + adversarial verify) proved the small-feature gap to perfectvector was POST-TRACE: raw vtracer already produces clean eyes (7 cubics) and an intact nose+mouth W (29 cubics); our own passes destroyed them. Fixes: - postprocess._is_linear_segment: absolute DP epsilon (~2px) reclassified small features' real curves as straight lines (eyes -> 5-7-sided polygons). Now uses a chord-RELATIVE test so a short cubic with a real bulge stays a curve. Eyes go from 14-29% curve polygons back to 100%-curve smooth ovals. - smooth.py: the nose+mouth W has curvature reversals but no sharp corners, so it was split into 2 arcs and fit straight across the concavities -> bowtie, mouth gone. Now also splits at signed-curvature reversals (inflections), resamples small contours denser, and — decisively — a per-feature AREA guard rejects a smoothing that fills a concavity (the bowtie) and keeps the crisp raw geometry. Nose is a clean rounded shape again and the mouth W is restored. No new deps (numpy only). 6-image set: no bloat/regression; suite green; corpus goldens recalibrated. Addresses the small-feature half of the v1.2->PV gap (outline-uniformity half tracked separately, needs the fill-and-inset stage). Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
The remaining gap to perfectvector is outline-width uniformity: PV holds an even ~12px band because its outline is a constant inset of one silhouette; ours is the byproduct of two independently-traced contours so the band wobbles (IQR 7-9px). Adds an OPT-IN --uniform-outline / ConvertOptions.uniform_outline (default OFF, color mode only): before tracing, force a constant-width band of the darkest palette color around the silhouette (skimage/scipy morphology — silhouette mask, erode by k, paint the ring). Makes the outer outline more even by construction. Opt-in because it assumes the art already has a dark outline around a solid-bg figure; on line art it would add a wrong border. The morphology re-smoothing means it is an improvement, not perfect parity (full parity needs vector polygon-offset + a geometry dep). Declares scipy as an explicit dep (was transitive via skimage). Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
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Closes #33, closes #34, closes #35, closes #36, closes #38, closes #39, closes #41
End-to-end quality overhaul driven by testing on real illustrations and reverse-engineering perfectvector.com output.
What changed (in order)
--uniform-outline: even outline band for outlined illustrations (default off).Result vs perfectvector (Shiba mascot)
Multi-agent deep-dives with adversarial verification confirmed the gaps were post-trace bugs in our own code (not vtracer/ML limits) and corrected several proposed fixes. Analysis:
~/Projects/docs/ANALYSIS-svgsmith-vs-perfectvector.md.85 tests green, ruff clean, corpus goldens recalibrated, no SSIM regressions. Remaining (tracked): #42 same-color union (fewer paths), #37 honest scoring, #40 defusedxml.
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