Convert photos to Atkinson dithering

264 nvahalik 30 6/7/2025, 8:33:18 PM gazs.github.io ↗

Comments (30)

JKCalhoun · 6h ago
Still my favorite B&W dither algorithm.

The university had a B&W flatbed scanner attached to a Mac running ... a Hypercard stack? that allowed you to scan an image and get a B&W image.

A clipart book I picked up from the college bookstore and a quick scan and I had a "logo" for the Mac shareware games I started writing in 1988 or so.

At the time I didn't;t realize how really ... nice .. Atkinson's algorithm is. But when, later, I tried dithering with other algos I saw how nice the diffusion was in Bill's code.

More recently I was playing with an eInk calendar project and wanted an "Atkinson-esque" series of images of the Moon in various phases. So I found a site very like the linked one to Atkinson-dither the moon photos I found [1].

[1] see the moon in screenshot: https://github.com/EngineersNeedArt/SystemSix/blob/10f2332b5...

nedt · 5h ago
Don't click the "as follows" in the info dialog. Looks like this wasn't updated in a while and since then the link became NSFW.
throwanem · 6h ago
The implementation is excellent, and could be slightly improved by giving a default name and .png extension to the downloaded file, by passing a value to the "download" property on the anchor. See https://developer.mozilla.org/en-US/docs/Web/API/HTMLAnchorE...
57473m3n7Fur7h3 · 5h ago
In his defence, that attribute has been available in browsers since March 2017 according to your link [1], whereas the most recent commit in the repo for the dithering tool was in March 2016 by the looks of it.

https://github.com/gazs/canvas-atkinson-dither

He’s still active on GitHub though, in other repos. Maybe he will accept a pull request? :)

[1]: https://developer.mozilla.org/en-US/docs/Web/API/HTMLAnchorE...

throwanem · 5h ago
Oh, I assumed it had been recently built and probably posted today by its author given the news and the lack of a year in the title. I'll open a PR.

edit: I might open a PR. 'CoffeeScript...now there's a name I've not heard in a long time. A long time...'

57473m3n7Fur7h3 · 5h ago
> CoffeeScript

It was acceptable in the 2010s

It was acceptable at the time

:p

https://www.youtube.com/watch?v=dOV5WXISM24

throwanem · 5h ago
Nor have I said there is anything wrong with it, only that it's been a long time. So reflexively to equate calling something old with calling it bad seems like a young man's game, but it has been some time since I had close experience of being one of those, also.
57473m3n7Fur7h3 · 5h ago
It’s a reference to the linked song. One of my favorite songs :D
minorbug · 4h ago
Here's one I've been working on and off that lets you convert multiple images to MacPaint in a 400k MFS formatted disk image.

https://github.com/minorbug/mfsjs

I've had this project gathering a light layer of dust in my home directory for a couple months now. I used Gemini Deep Research to help produce the library, and I included the LLM-generated markdown for anyone who wishes to reproduce on other languages, improve upon it, etc.

amelius · 6h ago
If you want to do this in Python, there's:

https://github.com/tgray/hyperdither

AndrewStephens · 6h ago
This implementation is great and the interface brings back memories.

I was wondering why my Atkinson dithering web-component[0] was getting more hits today - sad news. I’ve always thought that Atkinson dithering produces the nicest images on really crisp monitors like the original Mac - something about it just looks cool and 80s which is why I used it in a game last year.

[0] https://sheep.horse/2023/1/improved_web_component_for_pixel-...

shrinks99 · 2h ago
Woah cool web component!
RodgerTheGreat · 3h ago
A similar tool I wrote several years ago: http://beyondloom.com/tools/dith.html
zdw · 3h ago
Interesting that one of the size options is 512x384, not 512x342 which was the original mac resolution.
PlunderBunny · 1h ago
The very first Mac really was 512x342 [0]

0. https://512pixels.net/2025/05/original-macintosh-resolution/

Edit: Sorry - I misread what you were saying and intended this as a correction, but you had it right all along.

gcanyon · 3h ago
I think that's not a coincidence.
ksr · 6h ago
larodi · 6h ago
Is it the same Atkinson that died today and is this a tribute ?
zahlman · 6h ago
In a sense, but the first commit in the repository was 15 years ago - it's not something that someone whipped up in response to the news.
throwanem · 6h ago
Yes, he invented* the algorithm. One assumes it must be.

* Corrected from 'discovered;' see below.

zahlman · 6h ago
Invented the algorithm. The choice and arrangement of weights is a matter of fine-tuning to balance practical concerns - not some natural law of mathematics that could be figured out.
throwanem · 5h ago
I appreciate the correction.
4b11b4 · 6h ago
That's a good clarification
gcanyon · 5h ago
What am I doing wrong? I import a photo, I click save to desktop, and I get an unidentified file in an unknown format.
busymom0 · 4h ago
I believe the file is missing a name and extension. If you rename the file with .png extension, then it works.
gcanyon · 3h ago
HA! For some reason it never occurred to me that it would be in a format the original Mac never knew. Thanks!
ddingus · 6h ago
I just converted my home stereo. Pioneer, so lots of brushed metal. It looks really great at 2560x1440. Great dither.
htk · 3h ago
Thank you for posting this. Very nostalgic!
kgbcia · 4h ago
Would be great for eink/epaper devices.
9d · 4h ago
Sorry but where did you get the JS/CSS for this? It's so small.