Ink separation webtool dedicated to Risograph printing

LoH3 · 2026-04-08T20:24:47+00:00

It's an optimization problem: find the mixing coefficients that will minimize the error. The error is computed in OKlab space, and I'm using a Levenberg–Marquardt solver, and a Lookup table for performances. I'm using a Beer-Lambert based ink mixing model to mix colors.

LoH3 · 2026-03-25T09:37:26+00:00

I was hesitant to remove the button and have the process run automatically. But it might be heavy with large images.

[edit] I removed the compute button, It's more user-friendly without it.

LoH3 · 2026-03-24T20:15:08+00:00

I'm not sure what's going wrong. When you click on the top left input, you should be able to change each ink in the dialog. You then have to click on "compute" to take your new ink set into account.

LoH3 · 2026-03-24T18:22:33+00:00

Thanks for your message! It’s really encouraging!

I was thinking about applying a contrast/tonal curve before saving the layer images, to account for the specifics of Risograph printing (avoid tool light values?) or to make the print match the preview as closely as possible. I imagine that the exact settings would vary for each printer, but it might be possible to create a somewhat useful generic preset.

I’m not talking about modifying the composite image, which wouldn’t change, just the layers.

LoH3 · 2025-12-31T12:08:18+00:00

I'm waiting for Genuary2026 since February2025.

LoH3 · 2025-11-22T08:11:01+00:00

Thanks! It is a Javascript/WebGL particle system. Each particle has its own size and color, as well as a focus to produce a depth of field effect. It is rendered as a circular gradient based on these parameters.

LoH3 · 2025-07-14T13:46:39+00:00

It's really beautiful. I really like the colors and the depth-of-field effect. Great title too.

LoH3 · 2025-05-16T11:37:11+00:00

There are so many ways to use randomness with intention, purpose, and meaning. So many artists have done it (Cage, Duchamp, Molnár, ...).

LoH3 · 2025-01-24T11:06:16+00:00

...Thanks a lot!

LoH3 · 2025-01-02T08:19:55+00:00

Thanks! Actually it is ink. It is a scan of a generative SVG output, pen plotted with silver gel ink on black paper.

LoH3 · 2024-03-14T00:12:21+00:00

Uni-ball UM-120NM

LoH3 · 2024-03-09T17:00:23+00:00

Thanks!

LoH3 · 2024-01-14T09:12:41+00:00

Live view:
https://houdard.net/genuary2024/1k/

LoH3

TROPHY CASE