Contour Tracer

Converts a bitmap to closed SVG paths by running marching squares across the thresholded image, chaining the resulting line segments into contours, and simplifying with the Ramer–Douglas–Peucker algorithm. Best for clean linework, logos, and high-contrast images.

Ramer–Douglas–Peucker (RDP) is a path simplification algorithm. A raw contour from marching squares is a polyline with a point at every half-pixel — thousands of nearly-collinear points. RDP reduces this to the minimum set of points that still describes the same shape within a tolerance. It works recursively: draw a straight line from the first to the last point of the current segment; find the point furthest from that line; if it's within the tolerance, discard everything in between; if not, split there and recurse on both halves. The result is that long straight runs collapse to two points while tight curves keep their detail. The Simplify slider sets the tolerance in pixels — higher values produce smaller, smoother SVGs but lose fine detail.