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How My Images Are Dithered
- Retr0id 3mo agoI suppose it is a type of dithering, but really this is Halftoning
- Isamu 3mo agoYes, which of course is still cool. Probably the main point.
- AndrewStephens 3mo agoVery nice results, I really like the way it looks like a printed page. Image processing is addictive - once you start playing around it is hard to stop.
- ValdikSS 3mo ago??? This is halftoning, not dithering
- ValdikSS 3mo ago>Is this even dithering? >But if you care about the method this is not dithering. > I looked it up, the translation in this case is, in fact, simply "half tones" :^)
- andai 3mo agoSee also, Surface-stable fractal dithering: https://www.youtube.com/watch?v=EzjWBmhO_1E https://www.youtube.com/watch?v=EzjWBmhO_1E And the technical deep dive: https://www.youtube.com/watch?v=HPqGaIMVuLs https://www.youtube.com/watch?v=HPqGaIMVuLs
- ValdikSS 3mo agoThanks, that looks cool. This is dithering in principle, but using dynamic spot functions. To learn more about halftones, I'd recommend PDF specification, pages 303-307. https://opensource.adobe.com/dc-acrobat-sdk-docs/standards/pdfstandards/pdf/PDF32000_2008.pdf https://opensource.adobe.com/dc-acrobat-sdk-docs/standards/p...
- dahart 3mo agoI’d say halftoning is a specific type of dithering. Wikipedia mentions that for print, some people consider the terms synonymous. https://en.wikipedia.org/wiki/Dither#Applications https://en.wikipedia.org/wiki/Dither#Applications
- meindnoch 3mo agoEvery image should be dithered below 10 bits/component to prevent banding artifacts.
- dahart 3mo agoYeah this is important when you print images, since printers can reveal banding artifacts you can’t see on a monitor. I learned this the expensive way printing a batch of large format images that had gradients in them, without dithering. This is also how I learned one way that Photoshop was for professionals and GIMP & ImageMagick weren’t; At the time (and this was years ago, to be fair), Photoshop dithered by default when going from 16 to 8 bits, while those popular open source tools did not and also did not even have good ways to do it manually by adding the right amount of noise before changing the bit depth. I don’t know what the open source tools do today, maybe they’ve fixed it, I haven’t checked.
- meindnoch 3mo agoYeah. But even if you stay in the digital realm, dithering is necessary at 8bits per component. Consider that a grayscale gradient can only have 256 distinct levels.
- dahart 3mo agoTrue! You’re less likely to be surprised by banding on a display, because you can see it before it’s a problem, and it’s less likely to cost money, but for sure the need for dithering is still there, especially for displays that can do more than 8 bits per channel or can do high dynamic range. > Consider that a grayscale gradient can only have 256 distinct levels. This is true, but also keep in mind that for print and low dynamic range displays we humans only need approximately 256 levels, as long as the levels are perceptually spaced out evenly. 8 gamma corrected bits per channel actually made sense for a long time, for both print and for TVs & monitors, until HDR displays came along, relatively recently. Needing dithering for 8 bit images displayed on a 10 bit display is perhaps less surprising than needing dithering even when your display and your printer are both only 8 bits, right?
- rahimnathwani 3mo agoIf you're doing halftoning with the intent to get custom DTF (direct to film) prints for t shirts, you might find this tool helpful: https://tools.encona.com/dtf https://tools.encona.com/dtf It aims to 'knock out' some areas of the image: make them transparent in the digital image so those areas are not part of the final film. This means less of the surface of the t shirt has film on it, allowing it to be breathable and flexible. I got some DTF prints made before I knew you were meant to do this. The tutorials online required a lot of steps so I made the above for next time. Not tested for real yet.
- rgoodwintx 3mo agoBravo! One of my canary projects for LLMs has been a spot color / dithering tool; very much an amateur screen printer, and it seemed a way to spark my own interest to do some multicolor prints. Suffice to say the models couldn’t handle it, but I haven’t checked in a generation or two, so this is great motivation to try again!
- zahlman 3mo ago> DTF (direct to film) Very important clarification, there.
- xnx 3mo agoTitle here is missing "How" as in "How My Images Are Dithered"
- iTokio 3mo agoThat’s a hn filter to avoid clickbait titles I think
- gausswho 3mo agoMy Title Was Dithered
- jagged-chisel 3mo agoLossy compression
- Applejinx 3mo agoI went back to Ohio…
- petercooper 3mo agoWhich, more often than not, causes weird titles I’m more likely to click due to sounding curious and interesting, undoing the entire point of the feature. I would not have clicked on “How My Images Are Dithered” but this truncated version made it sound more like an interesting bug story.
- Tempest1981 3mo agoReminded me of how Safari removes the first word from tab titles
- ipunchghosts 3mo agoWhy is this not a typical data augmentation method for training deep networks? It would allow the networks to learn invariants that's align with humans. Currently, I suppose none of these dithered images would be correctly classified.
- trollbridge 3mo agoI’m sorry, but I can’t understand what you’re saying at all. Explain?
- ipunchghosts 3mo agoThere are many features in an image dataset which a can correctly classify the dataset. Neural nets usually focus in texture which we human clearly don't, we focus on a higher level abstraction and usually ignore texture. Using either would encourage the network to use broader features and ignore texture
- dist-epoch 3mo agoWhen someone says AI can't do something, I like to try it: > This image features a close-up abstract scene styled with a classic halftone (Ben-Day dot) pop-art filter ... https://share.gemini.google/O5eqZOKxwzw3 https://share.gemini.google/O5eqZOKxwzw3 > This image is a halftone/thermal print styled photograph. The photo features a group of four people posing closely together indoors or in front of a windowed backdrop: https://share.gemini.google/KJOxBDXYsFT4 https://share.gemini.google/KJOxBDXYsFT4
- ipunchghosts 3mo agoThis is a good way to think.
- dahart 3mo agoPerhaps because inference on dithered images is pretty rare, not a common or popular thing to do? Otherwise, people would train on dithered images. NNs are trained on noisy images. Training with dither would not learn any other invariants besides how to see through dither, it doesn’t automatically generalize to anything else.
- gausswho 3mo agoI vaguely recall stumbling across a site years ago that could do something like this in the browser, with various bits 'n bobs you could poke at. Can't find it now.
- willmeyers 3mo agoCool effect! It feels a bit like a deep-fried meme to me, but that might just be me! I tried doing something similar a couple of years ago and gave up after running into the exact same issues in the post. It's really difficult to replicate proper halftoning on a computer screen without getting moiré patterns and weird artifacts because of PPI, aliasing, and other stuff. Beyond that, print and screens are just fundamentally different ways of rendering things.
- Dwedit 3mo agoSpeaking of which, are there any good ways to undither images? Things like GIMP FFT are not perfectly reversible.
- trollbridge 3mo agoNo, although AI gets really close. Dithering represents adding noise to an image and also represents doing a lossy type of compression.
- jeremyscanvic 3mo agoIt's a somewhat active inverse problems research subfield https://github.com/MenghanXia/ReversibleHalftoning https://github.com/MenghanXia/ReversibleHalftoning
- Dwedit 3mo agoThat one does not seem to be an undither project, it appears to be a special way to encode chroma information within a monochrome dithered image. NTSC television also encodes chroma within a grayscale signal, but that's different than black and white only.
- qingcharles 3mo agoDo you want to undither, or un-half-tone, like the images in TFA? Unhalftoning is called descreening. I use this: https://descreen.net/ https://descreen.net/
- dahart 3mo agoDither loses information, so perfectly reversible might be an unreasonable goal. But I bet you could train or fine-tune a denoiser to do a really good job. This might make a cool paper, if there’s anything at all non-standard or surprising you discover along the way.
- Dwedit 3mo agoWhen I mentioned "perfectly reversible", I meant the FFT itself. You run the FFT. You run the inverse FFT. Because the FFT was quantized to 0-255, you end up with a lot of stuff that doesn't belong in the image.
- ReactiveJelly 3mo ago> Dithering can reduce file size Yeah, if you're using lossless compression like PNG or GIF, adding a lossy step to reduce the number of colors in the palette can help. If you're compressing photos, you should use JPEG or WebP. Anecdotally, JPEG usually beats dithering, and WebP always does. It's fine to dither images but please please admit that you're doing it for the aesthetic. WebP has very broad browser support and absolutely blows dithering out of the water for compression. You are not going to beat years of research and tuning with "use fewer colors". I remember a YouTube video about "How we did the impossible and got full-motion video for this Sonic game on a system that couldn't do FMVs", and the answer was like, "Well, we used a low resolution, and then we reduced the color palette, and then we cut the frame rate, and then we did interlacing." None of that's impossible! That's like saying you built the Pyramid at Giza using only a bucket of Lego bricks! It's not the same pyramid! Anyone can use a lower resolution! It takes effort and teamwork to come up with a codec that actually compresses data without artifacts!
- galleywest200 3mo ago> It's fine to dither images but please please admit that you're doing it for the aesthetic They did in the article. > My goal was to immitate a printed image.
- zahlman 3mo agoSure, but offering a weak file-size justification alongside that confuses the message.
- mort96 3mo ago.. What do you mean by "beats" here? Is the article trying to hide the fact that they're doing dithering for, among other things, artistic reasons? A dithered image almost certainly beats a non-dithered JPEG compressed image in terms of file size, because you can JPEG compress the dithered image. Thus, if you like the look of a dithered image, you get file size reduction as a bonus. I swear, some people on HN intentionally misinterpret and misrepresent the text of an article just to argue against it in bad faith with these smarmy "um actually" type arguments. For some reason I do not understand, Hacker News tends to surface these comments near the top of its comment sections.
- trentor 3mo agoI was a rotogravure printer in another life, and this post made me a bit nostalgic. In intaglio printing you usually don't see these patterns because the electrostatic assist pulls the ink out of the cells, and the colors blend together more. It's more akin to a developed photo. I mainly remember them from having to do offset printing for the intermediate exam during my apprenticeship. Our paper was about 3.5 meters wide, and a single roll length was 2–3 kilometers which ran for 20-30 minutes. The process delivered high quality at high speed, so we printed titles like Playboy and the IKEA catalogue in every language (for a language change we only had to swap the black cylinders, since the data was optimized so the text was mostly single color black). A print run of the IKEA catalogue, around 40 million copies, took about two months. It was brain numbing but also really zen. I miss it sometimes.
- inigyou 3mo agoI can imagine that feeling of "being a cog in a beautiful machine" gets a lot less people these days because so many cogs are automated and so many machines are no longer beautiful.
- nicbou 3mo agoOn the other hand I vaguely remember a comment from a printer who was radicalised by the amount of paper wasted on printing flyers, day after day, week after week.
- rrr_oh_man 3mo agoCounterpoint: https://news.ycombinator.com/item?id=29227606 https://news.ycombinator.com/item?id=29227606
- tiffanyh 3mo agoIf you like this, you might also like: https://news.ycombinator.com/item?id=48009879 https://news.ycombinator.com/item?id=48009879
- AyanamiKaine 3mo agoOhhhh that is so cool, but I agree with the others its more halftoning. When you want to dither/pixelate an image you can use Image-to-Pixel [0]. [0]https://tezumie.github.io/Image-to-Pixel/ https://tezumie.github.io/Image-to-Pixel/
- next_xibalba 3mo agoIt tickles me greatly how much HN’ers are fascinated by dithering. It seems like a few times per year a post about dithering makes the front page.
- jcynix 3mo agoHmm, that gives me an idea: dithering (of generally "mogrifying") my images might make them less palatable for those pesky AIs roaming my web server …
- ectoloph 3mo agoDidder[0] is a good tool for dithering. I use it to pre-process images for the 6-color e-ink displays. You can go down a rabbit hole of dithering algorithms too, like Floyd Steinberg[1] [0] https://github.com/makew0rld/didder https://github.com/makew0rld/didder [1] https://en.wikipedia.org/wiki/Floyd%E2%80%93Steinberg_dithering https://en.wikipedia.org/wiki/Floyd%E2%80%93Steinberg_dither...
- bthallplz 3mo agoHave you posted anywhere online about your experiences with color e-ink displays? I think they're super neat, and I love the idea of using dithering for them. :D
- olivierestsage 3mo agoRecommended: https://doodad.dev/dither-me-this/ https://doodad.dev/dither-me-this/
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- timnetworks 3mo agoIs nobody going to mention anything about the fact that one of the friends at the restaurant has no _head_ ?
- effnorwood 3mo agoslowly. then all at once.
- imhoguy 3mo agoUp! Very cool site, creative, slopless and with that 90/00s vibe I miss :)
- zeraye 3mo agoA few years ago I made this fun little app https://dithering-sigma.vercel.app/ https://dithering-sigma.vercel.app/. May be interesting for someone. Source code https://github.com/zeraye/dithering https://github.com/zeraye/dithering.
- matsemann 3mo agoAlmost two decades ago I used a software called Rasterbator to dither an image into dots, blowing it up to multiple A4 pages one could then decorate a whole wall with. Up close it would just be circles of various sizes, but from a distance the image would show up. Super cool. Used it to decorate a wall in my dorm with a picture of the family dog. Edit: found it. One picture taken from up close. Other pictures the whole image when laid out over multiple pages in the software https://imgur.com/a/OeaIWuY https://imgur.com/a/OeaIWuY
- bthallplz 3mo agoNeat! I really liked the look of the Floyd-Steinberg algorithm in the article, so when I googled for a web tool that'll do it for me, I found the tool mentioned here: https://www.ascii-magic.com/styles/dither https://www.ascii-magic.com/styles/dither It has some fun animation options and settings to play with, and there's other dithering algorithms to play with.
- AussieWog93 3mo agoImmediately recognised the "dot in the hexagon" effect, it looks amazing!
- gforce_de 3mo agoI like it! But i'm not so sure about the filesize safings mentioned. Your dithered "truedinner.webp" has 189.166 bytes. The original image has 34.682 bytes with JPEG. https://show.quicky.club/results/b5/30/12/16f36013492e06b658268db157709b9d18318645941f915ceb2ac87072-3513926.html https://show.quicky.club/results/b5/30/12/16f36013492e06b658...