More Voronoi tools

Voronoi Diagram GeneratorClick to add cells, relax and recolor Image to Voronoi MosaicStained-glass mosaic from a photo Lloyd RelaxationCentroidal Voronoi, step by step Voronoi Pattern GeneratorCell patterns with gaps and rounded corners Delaunay Triangulation GeneratorThe dual of the Voronoi diagram Weighted VoronoiPower and multiplicative diagrams What Is a Voronoi Diagram?Guide with interactive figures

What is Voronoi stippling?

Stippling is the art of drawing with dots: dark areas get many dots, light areas few. Weighted Voronoi stippling, introduced by Adrian Secord in 2002, automates it. Dots are first scattered according to the image's darkness, then each dot is moved to the darkness-weighted centroid of its Voronoi cell. Repeating this spreads the dots evenly while keeping them dense where the image is dark — the look of a careful hand-made stipple drawing.

How to use it

  1. Choose an image or keep the demo picture. Portraits and objects on a plain background work best.
  2. Set the number of dots. Two to six thousand is a good range for most images.
  3. Let it run. Each iteration refines the layout; pause or step through it to watch.
  4. Raise Contrast to push dots out of mid-tones, or Invert for light dots on a dark paper.
  5. Turn on Size dots by tone for bigger dots in dark areas.

How it works

The image is reduced to at most 600 pixels on its long side and converted to a darkness map. In each iteration, every pixel is assigned to its nearest dot, and each dot's new position is the average of its pixels' positions weighted by their darkness. This is Lloyd's algorithm with a density function — see the Lloyd relaxation tool for the unweighted version. For a filled-cell look instead of dots, try Image to Voronoi Mosaic.

Frequently asked questions

What is weighted Voronoi stippling?

It is a method published by Adrian Secord in 2002. Dots are scattered according to the darkness of an image, then repeatedly moved to the darkness-weighted centroid of their Voronoi cell. Dots end up evenly spaced but denser in dark areas, like a hand-drawn stipple illustration.

How many iterations are needed?

Most images settle in 20 to 50 iterations. The movement figure in the corner shows how far dots moved in the last step; once it is below about a tenth of a pixel the picture will barely change.

Can I use the result for a pen plotter?

The dot layout is exactly the kind used for pen-plotter and laser-engraving portraits. Use high-contrast images and a few thousand dots for the cleanest result.

Is my image uploaded?

No. The image is processed entirely in your browser.

All Voronoi tools