dither

dither explores funny textures for ordered dithering.

I wanted to make riso’s noise more satisfying, and so instead of using noise, I started poking at ordered dithering, which is a way to display a grayscale image using only black and white. One approach is to create a little repeating grayscale tile that says at what level to turn that pixel on.

A common ordered dithering approach creates little cross-hatch patterns, but you can also use custom filters to create things like a halftone pattern or blue noise. I created a few patterns using numpy, stacked them into one image, and then spent far too long trying to write a shader to crop and repeat the pattern without seams.

Now I can apply it on top of drawings or sdfs. Here’s a still from a recent set that uses dithering along with sdfs and a cell division algorithm.

I also like how complicated it looks when animated with smooth gradients. Here’s radial noise going through ordered dithering using a pattern of blue noise and a herringbone pattern from my shower.

You can use more than two colors if you adjust the thresholds for each color. Here’s a close-up of a halftone pattern made with Gaussians using 3 levels.

Some additional links I found useful:

• This video explains ordered dithering.
• This post helped me create a blue noise filter.
• This forum post by Lucas Pope shares the challenge of applying dithering to a 3D game. Thankfully I’m in the 2D world so didn’t need to worry about this.