All articles · 2026-09-05

Getting real gradients out of a raster image

How smooth shading becomes linear and radial gradient fills in SVG, PDF and EPS instead of dozens of banded shapes.

Traditional auto-tracing turns a smooth sphere into concentric bands — ugly to look at and painful to edit. A gradient-aware engine finds regions where the colour changes smoothly, fits a linear or radial model, and writes a single shape with a gradient fill.

How the fit works

Curvora groups pixels into smooth surfaces, splits them into colour-coherent pieces and merges neighbouring pieces while one gradient still explains them. Outliers such as a highlight on a sphere or a shadow on a backdrop are trimmed and handled on their own. The exported gradient has five stops so the on-screen result matches the perceptual fit closely.

Where it stops

Mesh-like shading and photographic lighting are still approximated with flat levels. You can switch gradient detection off in the advanced settings if you prefer bands for a particular style.