potrace

Image

1 · threshold

channel

cutoff 128

Pixels darker than this → foreground

mode

blur radius 0

Gaussian pre-blur to smear compression halos into ink before thresholding.

invert

1.5 · skeleton Zhang-Suen thinning

Reduce strokes to 1px centerlines before tracing. Best for line drawings.

2 · trace filter

min pts 4

Drop contours with fewer points than this — removes isolated noise pixels.

3 · simplify

RDP ε 2

Max deviation when dropping collinear points. Higher → blockier, fewer vertices.

4 · bézier lines only (skip curve fitting)

corner cos θ -0.5

Turning-angle cosine below this = corner (line). −1 = all curves, +1 = all lines.

max error 1

Max RMS fit error (px) before splitting an arc. Lower → smoother, more segments.

max depth 4

Recursion depth when splitting a bad fit.

max arc pts 32

Max polygon points per fitted arc. Long arcs are chunked before fitting — prevents diagonal cuts on complex shapes.

5 · svg debug show holes in red

outers = black, holes = red — shows which regions are subtracting fill