Halftone Effect Generator

Halftone is how printing presses show grey with only black ink: a grid of dots that grow in dark areas and shrink in light ones. The same pattern gives pop-art posters, comic panels and screen-print designs their look. This generator screens your picture with dots, lines, squares or crosses at the cell size and angle you choose, in one ink, four CMYK inks or RGB light, and can save the mono version as a vector SVG for vinyl cutters, laser engravers and large prints.

How to use this tool

1. Choose one or more images.
2. Pick the pattern and the cell size; 6–10 px looks like print, 20 px and more like pop art.
3. Pick mono with your own ink and paper colours, or CMYK / RGB for colour.
4. Download the PNG, and the SVG if you need a scalable vector.

Formula

darkness d = 1 − luma ÷ 255 (averaged over 16 points in the cell); dot radius r = cell × √(d ÷ π), so the dot covers d of the cell

Squares have side cell × √d, lines thickness d × cell, and crosses arm thickness cell × (1 − √(1 − d)), so each shape inks the same share of its cell. Above d = π/4 (≈ 0.79) neighbouring dots touch, and the radius then grows linearly to cell × √½, where the cell is fully covered. The grid is rotated by the screen angle around the image centre. CMYK splits each colour with K = 1 − max(R, G, B) and C = (1 − R − K) ÷ (1 − K); RGB mode adds red, green and blue dots on black.

Example

With 8 px cells, a mid-blue area of luma 95.6 has darkness 1 − 95.6 ÷ 255 = 0.625, so each dot gets radius 8 × √(0.625 ÷ π) = 3.57 px — it covers 62.5% of its 64 px² cell. A light yellow with luma 192.6 (darkness 0.245) gets 2.23 px dots.