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Why do we need dithering?
- abstractspoon 1y agoThey answered the question in the first two sentences: We don't need it, it's just an aesthetic nowadays.
- debugnik 1y agoIt's not just aesthetic, I keep seeing games with color banding because they don't bother to dither before quantizing.
- amelius 1y agoFrom the article: > We don't really need dithering anymore because we have high bit-depth colors so its largely just a retro aesthetic now. By the way, dithering in video creates additional problems because you want some kind of stability between successive frames.
- dTal 1y agoYeah, the article is wrong about that.
- amelius 1y agoIt would be nice if you had some examples.
- nofriend 1y agosee eg https://xcancel.com/theo/status/1978161273214058786?s=46 https://xcancel.com/theo/status/1978161273214058786?s=46
- slabity 1y agoAcerola recently made a video about how Silk Song has banding with dark colors due to poor dithering (and how to fix it): https://www.youtube.com/watch?v=au9pce-xg5s https://www.youtube.com/watch?v=au9pce-xg5s Highly recommend for any graphics programmer that might think dithering is unnecessary or simply a "aesthetic choice".
- knollimar 1y agoTo lend more credibility, the devs added more dithering in the next patch.
- dTal 1y agoA great many can be found here: https://en.wikipedia.org/wiki/Dither https://en.wikipedia.org/wiki/Dither (also a very nice explanation of why dithering is a fundamental signal processing step applicable to many fields, not just an "aesthetic".)
- amelius 1y agoInteresting!
- Dylan16807 1y agoThe average desktop computer is running with 8 bit color depth the vast majority of the time, so find or generate basically any wide basic gradient and you'll see it.
- doormatt 1y agoI think you mean 24 bit. 8 bit would only be 256 colors total.
- recursive 1y ago8 bits for each of R G and B. So a grey-scale gradient indeed has only 256 colors available. Any gradient also will have about that many at most.
- kragen 1y agoIn most gradients, the transitions in R, G, and B are at different places.
- recursive 1y agoTrue. Also, in most gradients, the full range of R G and B is not used. In rgb(50, 60, 70) to rgb(150, 130, 120), there are only 200 total transitions.
- kragen 1y agoTrue!
- mrandish 1y agoIn terms of color spaces, SRGB (the typical baseline default RGB of desktop computing) is quite naive and inefficient. Pretty much its only upsides are its conceptual and mathematical simplicity. There are much more efficient color spaces which use dynamic non-linear curves and are based on how the rods and cones in human eyes sense color. The current hotness for wide color gamuts and High Dynamic Range is ICTCP (https://en.wikipedia.org/wiki/ICtCp https://en.wikipedia.org/wiki/ICtCp) which is conceptually similar to (https://en.wikipedia.org/wiki/LMS_color_space https://en.wikipedia.org/wiki/LMS_color_space).
- electroly 1y agoA very simple black-to-white gradient can only be, at most, 256 pixels wide before it starts banding on the majority of computers that use SDR displays. HDR only gives you a couple extra bits where each bit doubles how wide the gradient can be before it starts running out of unique color values. If the two color endpoints of the gradient are closer together, you get banding sooner. Dithering completely solves gradient banding.
- deleted 1y ago[deleted]
- Sesse__ 1y agoYou can do with a static dither pattern (I've done it, and it works well). It's a bit of a trade-off between banding and noise, but at least static stuff stays static and thus easily compressable.
- TinkersW 1y agoThe article is simple wrong, dithering is still widely used, and no we do not have enough color depth to avoid it. Go render a blue sky gradient without dithering, you will see obvious bands.
- mrandish 1y agoYep, even high quality 24-bit uncompressed imagery often benefits from dithering, especially if it's synthetically generated and, even if it's natural imagery, if it's processed or manipulated - even mildly - it'll probably benefit from dithering. If it's a digital photograph, it was probably already dithered during the de-bayering process.
- jchw 1y agoDithering can be for aesthetic reasons, I presume especially old-school dithering that is especially pronounced. However, dithering is actually still useful in all sorts of signal processing, particularly when there are perceptible artifacts of quantization. This occurs all the time: you can trivially observe it by making gradients that go between close looking colors, something you can see on the web right now. There are many techniques to avoid banding like this, but dithering lets you hide banding without needing increased bit depth or choosing strategic stop colors by trading off spatial resolution for (perceived) color resolution, which works excellently for gradients because it's all low frequency. And frankly, it turns out 256 colors is quite a lot of colors especially for a small image, so with a very good quantization algorithm and a very good dithering algorithm, you can seriously crunch a lot of things down to PNG8 with no obvious loss in quality. I have done this at many of my employers, armed with other tricks, to dramatically reduce page load sizes.
- matja 1y agoDithering isn't only applied to 2D graphics, it can be applied in any type of spatial or temporal data to reduce the noise floor, or tune aliasing distortion noise to other parts of the frequency spectrum. Also common in audio.
- tinkelenberg 1y agoThis is the best explanation I’ve come across. I enjoy dithering as a playful way to compress file size when it makes sense.
- dcrazy 1y agoSlightly frustrating the author started out with color images and then switched to grayscale.
- raajg 1y agoThis was recently shared on HN: https://visualrambling.space/dithering-part-1/ https://visualrambling.space/dithering-part-1/ For anyone interested in seeing how dithering can be pushed to the limits, play 'Return of the Obra Dinn'. Dithering will always remind you of this game after that. - https://visualrambling.space/dithering-part-1 https://visualrambling.space/dithering-part-1 - https://store.steampowered.com/app/653530/Return_of_the_Obra_Dinn/ https://store.steampowered.com/app/653530/Return_of_the_Obra...
- amiga386 1y agoOn Return of the Obra Dinn's dithering specifically, here is the original developer blog on its dithering: https://forums.tigsource.com/index.php?topic=40832.msg1363742#msg1363742 https://forums.tigsource.com/index.php?topic=40832.msg136374... It's intended, aesthetically, to remind you of Atkinson dithering (https://en.wikipedia.org/wiki/Atkinson_dithering https://en.wikipedia.org/wiki/Atkinson_dithering), a variant of Floyd-Steinberg dithering often used in graphics for the black-and-white Macintosh.
- susam 1y agoThis is going to be an odd comment, but I immediately recognised the parrot in the test images. It's the scarlet macaw from 2004 which is often used in many Wikipedia articles about colour graphics. I think this is the original, photographed and contributed by Adrian Pingstone: https://commons.wikimedia.org/wiki/File:Parrot.red.macaw.1.arp.750pix.jpg https://commons.wikimedia.org/wiki/File:Parrot.red.macaw.1.a... But this particular derivative is the one that appears most often in the Wikipedia articles: https://commons.wikimedia.org/wiki/File:RGB_24bits_palette_sample_image.jpg https://commons.wikimedia.org/wiki/File:RGB_24bits_palette_s... This parrot has occurred in several articles on the web. For example, here's one article from a decade or so ago: https://retroshowcase.gr/index.php?p=palette https://retroshowcase.gr/index.php?p=palette Parrots are often used in articles and research papers about computer graphics and I think I know almost all the parrots that have ever appeared in computing literature. This particular one must be the oldest computing literature parrot I know! By the way, I've always been fascinated by dithering ever since I first noticed it in newspapers as a child. Here was a clever human invention that could produce rich images with so little, something I could see every day and instinctively understand how it creates the optical illusion of smooth gradients, long before I knew what it was called.
- malfist 1y agoThis also used to be a really common test image: https://en.wikipedia.org/wiki/Lenna https://en.wikipedia.org/wiki/Lenna But its apparently a cropped centerfold from Playboy
- tux3 1y agoThe original Lenna is controversial, but I'm delighted to share the "ethically sourced Lenna": https://mortenhannemose.github.io/lena/ https://mortenhannemose.github.io/lena/
- ziml77 1y agoThis feels better than the original anyway. I never liked the yellow color that one had. Maybe it was an artistic choice, but to me it just looked degraded, like when white plastic is left exposed to the sun.
- andai 1y agoAlso by the author: https://www.makingsoftware.com/ https://www.makingsoftware.com/ Recent discussions: Making Software - https://news.ycombinator.com/item?id=43678144 https://news.ycombinator.com/item?id=43678144 How does a screen work? - https://news.ycombinator.com/item?id=44550572 https://news.ycombinator.com/item?id=44550572 What is a color space? - https://news.ycombinator.com/item?id=45013154 https://news.ycombinator.com/item?id=45013154
- grep_it 1y agoI love the authors style!
- 01HNNWZ0MV43FF 1y agoPlaydead Games did a really nice presentation about dithering for games, it gets passed around and I'm sure it's been on HN already: https://loopit.dk/banding_in_games.pdf https://loopit.dk/banding_in_games.pdf
- Dylan16807 1y ago> Before we all mute the word 'dithering' Is this a reply to something?
- tshaddox 1y agoYes, it's referencing a tweet which briefly made the rounds a few weeks ago: https://x.com/TukiFromKL/status/1981024017390731293 https://x.com/TukiFromKL/status/1981024017390731293 Many people believed that the author was claiming to have invented a particular illustration style which involved dithering.
- Cockbrand 1y agoThe cringe is strong with this one. (Thanks for the heads up, I hadn't seen that)
- hcs 1y agoYou still see dithering from time to time as a cheap transparency, it's been a few years since Mario Odyssey but that's when last I recall it really stood out: https://xcancel.com/chriswade__/status/924071608976924673 https://xcancel.com/chriswade__/status/924071608976924673
- BigJono 1y agoThis is what I'm doing for my game, I didn't know it was actually a thing in some big titles too, that's reassuring. I landed on it because it was a huge code simplification compared to every other method of handling transparency, and it doesn't look completely shit in the era of high resolutions and frame rates.
- Auracle 1y agoI just implemented it for a VR app I’ve been working on where the semi-transparent objects can appear any which way, intersecting, etc. I didn’t realize how much of an issue that’d be…or how hard it’d be to come up with a shader for dithering in VR that doesn’t look awful. I’m still not super happy with what I have - it moves along with the player’s eyes - but every other solution I could come up with didn’t interact well with two screens, especially at far distances from the object. Moire for days.
- lepicz 1y agomafia2 used that as well (at least for cars appearing into your bubble)
- magicalhippo 1y agoFirst time I saw it was in the original Unreal game (1998) when using the software renderer. It had this very distinct asymmetric dithering pattern. Can't find a screenshot of it on short order, seems most screenshots are either of unrelated newer Unreal Engine or use hardware rendering which doesn't show this dithering.
- mrguyorama 1y ago
- mrandish 1y agoA related bit of tech trivia is that digital audio also often involves dithering, and not just decimated or compressed audio. Even very high-quality studio mastered audio benefits from an audio specific kind of dithering called noise shaping. Depending on the content, studio mixing engineers may choose different noise shaping algorithms. https://en.wikipedia.org/wiki/Noise_shaping https://en.wikipedia.org/wiki/Noise_shaping
- olivia-banks 1y agoThe figures in this article are really great. How where they made? If I was to try and recreate them I might render things individually and then lay it out in Illustrator to get that 3D isomorphic look, but I assume there's a better way.
- kragen 1y agoWe've had a couple of other recent discussions on dithering: https://news.ycombinator.com/item?id=45750954 https://news.ycombinator.com/item?id=45750954 and https://news.ycombinator.com/item?id=45698323 https://news.ycombinator.com/item?id=45698323. I commented specifically about the history of blue-noise dithering at https://news.ycombinator.com/item?id=45728231 https://news.ycombinator.com/item?id=45728231. The article points out that, historically, RAM limitations were a major incentive for dithering on computer hardware. (It's the reason Heckbert discussed in his dissertation, too.) Palettizing your framebuffer is clearly one solution to this problem, but I wonder if chroma subsampling hardware might have been a better idea? The ZX Spectrum did something vaguely like this: the screen was 256×192 pixels, and you could set the pixels independently to foreground and background colors, but the colors were provided by "attribute bytes" which each provided the color pairs for an 8×8 region http://www.breakintoprogram.co.uk/hardware/computers/zx-spectrum/screen-memory-layout http://www.breakintoprogram.co.uk/hardware/computers/zx-spec.... This gave you a pretty decent simulation of a 16-color gaming experience while using only 1.125 bits per pixel instead of the 4 you would need on an EGA. So you got a near-EGA-color experience on half the RAM budget of a CGA, and you could move things around the screen much faster than on even the CGA. (The EGA, however, had a customizable palette, so the ZX Spectrum game colors tend to be a lot more garish. The EGA also had 4.6× as many pixels.) Occasionally in ZX Spectrum game videos like https://www.youtube.com/watch?v=Nx_RJLpWu98 https://www.youtube.com/watch?v=Nx_RJLpWu98 you will see color-bleeding artifacts where two sprites overlap or a sprite crosses a boundary between two background colors. For applications like CAD the problem would have been significantly worse, and for reproducing photos it would have been awful. The Nintendo did something similar, but I think had four colors per tile instead of two. So, suppose it was 01987 and your hardware budget permitted 8 bits per pixel. The common approach at the time was to set a palette and dither to it. But suppose that, instead, you statically allocated five of those bits to brightness (a Y channel providing 32 levels of grayscale before dithering) and the other three to a 4:2:0 subsampled chroma (https://www.rtings.com/tv/learn/chroma-subsampling https://www.rtings.com/tv/learn/chroma-subsampling has nice illustrations). Each 2×2 4-pixel block on the display would have one sample of chroma, which could be a 12-bit sample: 6 bits of U and 6 bits of V. Moreover, you can interpolate the U and V values from one 2×2 block to the next. As long as you're careful to avoid drawing text on backgrounds that differ only in chroma (as in the examples in that web page) you'd get full resolution for antialiased text and near-photo-quality images. That wouldn't liberate you completely from the need for dithering, but I think you could have produced much higher quality images that way than we in fact did with MCGA and VGA GIFs.
- firebot 1y agoWe really don't anymore. Back in the late 90s maybe. Gifs and other paletted image formats were popular. I even experimented with them. I designed various formats for The Palace. The most popular was 20-bit (6,6,6,2:RGBA, also 5,5,5,5; but the lack of color was intense, 15 bits versus 18 is quite a difference). This allowed fairly high color with anti-aliasing -edges that were semi transparent.
- aidenn0 1y agoWe absolutely still need dithering; 24-bit sRGB is not nearly enough for a large monochromatic gradient to not have visible banding without dithering.
- mordae 1y agohttps://en.wikipedia.org/wiki/Frame_rate_control https://en.wikipedia.org/wiki/Frame_rate_control Your screen likely uses dithering to produce 1-2 LSBs of each color channel of this piece of graphics right now.
- cmovq 1y agoDithering is still very common in rendering pipelines. 8 bits per channel is not enough to capture subtle gradients, and you’ll get tons of banding. Particularly in mostly monochrome gradients produced by light sources. So you render everything to a floating point buffer and apply dithering. Unlike the examples in this post, this dithering is basically invisible at high resolutions, but it’s still very much in use.
- black_knight 1y agoAnother place where dithering is useful in graphics is when you can’t do enough samples in every point to get a good estimation of some value. Add jitter to each sample and then blur, and then suddenly each point will be influenced by the samples made around them, giving higher fidelity. I recently learned the slogan “Add jitter as close to the quantisation step as possible.” I realised that “quantisation step” is not just when clamping to a bit depth, but basically any time there is an if-test on a continuous value! This opens my mind to a lot of possible places to add dithering!
- 01HNNWZ0MV43FF 1y agoHell, one could dither vertex positions and normals
- zozbot234 1y agoA lot of display hardware uses a combination of spatial and temporal dithering these days. You can see it sometimes if you look up close, it appears as very faint flickering "snow" (the kind you'd see on old analog TV). Ironically, making this kind of dithering even less perceivable may turn out to be the foremost benefit of high pixel resolutions (beyond 1080p) and refresh rates (beyond 120Hz) since it seems that raising those specs is easier than directly improving color depth in hardware.
- quitit 1y agoAdobe Illustrator 2026 has only -just- added a dithering option to their gradient tool.
- kettlecorn 1y agoDithering is super useful in dark scenes in games and movies. By adding random noise to the screen it makes bands of color with harsh transitions imperceptible, and the dithering itself also isn't perceptible. I'm sure there are better approaches nowadays but in some of my game projects I've used the screen space dither approach used in Portal 2 that was detailed in this talk: https://media.steampowered.com/apps/valve/2015/Alex_Vlachos_Advanced_VR_Rendering_GDC2015.pdf https://media.steampowered.com/apps/valve/2015/Alex_Vlachos_... It's only a 3 line function but the jump in visual quality in dark scenes was dramatic. It always makes me sad when I see streamed content or games with bad banding, because the fix is so simple and cheap! One thing that's important to note is that it's a bit tricky to make dithering on / off comparisons because resizing a screenshot of a scene with dithering makes the dithering no longer work unless one pixel in the image ends up exactly corresponding to one pixel on your screen
- mordae 1y agoIt's not cheap for streaming. It's harder to compress and is lost in the process. The video codec is a smart low pass filter.
- kalleboo 1y agoThe AV1 codec has support to tell the decoder to generate fake film grain, so you can add back all the noise lost in compression. Although I don't think it's very widely used, I dunno if that's due to the compressors or decompressors.
- kettlecorn 1y agoIt needs to be done by the client and not be part of the actual video stream, otherwise it doesn't even work. When done by the client it's cheap.
- jasomill 1y agoNot so cheap if your hardware decoder only supports 8-bit color, which is a common limitation of H.264 decoders in particular.
- WheatMillington 1y agoWhat an insanely beautiful website. Reminds me of the golden days of the internet, remastered tastefully.
- efilife 1y agoWhat's with the dithering trend? Why do I keep hearing about it everywhere at least once a week? Where did this originate from?
- mordae 1y agoPhysics.
- Gigachad 1y agoEven though it looks less accurate, I prefer the look of the Ordered Bayer image. It looks artistically low-fi while the others look more like a highly compressed image to me. Considering we are able to just represent images with full colour today, the only reason I'd dither is for the aesthetic.
- OCTAGRAM 1y agoI have noticed author uses values 0-255 for shades of grey. When 0-255 range is used, this is usually nonlinear scale with average gamma 2.2. And de facto there is a standard function that maps 0-31 to linear function and the rest to power 2.4. Average power 2.2. Checkmate black 0 and white 255 is equavalent to uniform grey shade 185 or 186 as opposed to 127 or 128. Proper calculations should be done in linear space, and 16 bits per channel is desired at least.
- deleted 1y ago[deleted]
- vismit2000 1y agoEarlier submission: https://news.ycombinator.com/item?id=45743067 https://news.ycombinator.com/item?id=45743067
- chromehearts 1y agoCan somebody explain to me how dithering is an aesthetic (as mentioned in the article)? I feel I'm too young to understand that
- harperlee 1y agoIt's related to nostalgia. If you have lived at the time where dithering was used, you will have an emotional response to it. For example, if you played games as a child with dithering, then playing The Return of the Obra Dinn, which was mentioned in other thread, will take you back to a happy place. And even if you did not live at that time, exposure to that distinct visual style will also start having meaning to you. Like how an exposed brick interior wall has a distinct aesthetic, and carries connotations of an industrial space.
- badlibrarian 1y agohttps://en.wikipedia.org/wiki/Atkinson_dithering https://en.wikipedia.org/wiki/Atkinson_dithering
- imtringued 1y agohttps://shared.fastly.steamstatic.com/store_item_assets/steam/apps/410970/ss_e1c85315d608fc9ee27ed880ab941afbbaabd727.1920x1080.jpg?t=1708071592 https://shared.fastly.steamstatic.com/store_item_assets/stea... https://shared.fastly.steamstatic.com/store_item_assets/steam/apps/410970/ss_a50b04b27ad755d937f969ec7b7b91b853cf9a9d.1920x1080.jpg?t=1708071592 https://shared.fastly.steamstatic.com/store_item_assets/stea... https://store.steampowered.com/app/410970/Master_of_Orion_1/ https://store.steampowered.com/app/410970/Master_of_Orion_1/
- mytailorisrich 1y agoWe don't really need dithering anymore because we have high bit-depth colors so its largely just a retro aesthetic now. I think "retro aesthetic" is quite plain as to what it means. You needed to read on ;)
- kqr 1y agoI haven't written about this yet but I don't often see it mentioned: dithering has applications outside of image processing. Any time one needs to create a sequence sampled from a distribution, but would like to do so "evenly" without creating lumps, Floyd–Steinberg is a decent candidate.
- a-french-anon 1y agoSomething that really blew my mind, as someone who didn't study much signal processing: https://www.audiosciencereview.com/forum/index.php?threads/dithering-is-a-mathematical-process-not-a-psychoacoustic-process.11169/ https://www.audiosciencereview.com/forum/index.php?threads/d... The tl;dr is that dither isn't just for the eyes, it's mathematically needed to preserve information when undergoing quantization.
- ant6n 1y agoSo, uh, why do we need dithering? I thought the era of 4 bit color had passed.
- vardump 1y agoDithering is usually used up to 18-bit color (6 bits each red, green and blue components). But it's useful even past that to reduce banding.
- stavros 1y agoIs zooming disabled for anyone else? The article depends on me looking at the photos, but they're the size of a MicroSD card on my screen, and zooming in is disabled on this site!
- charlie-83 1y agoFor some good examples, check out what people have achieved on the PlayDate handheld with dithering on its 1-bit screen.
- smougel 1y agoJust Vibecoded this : https://x.com/smougel/status/1989309185423532120?s=20 https://x.com/smougel/status/1989309185423532120?s=20 Subpixel dithering ! 1 bit per channel which mean that what you see is only 0 or 1 for each channel (R, G, B) By using gaussian blur, the result is perceptually very good ! X compress the image a lot but this truly 1 subpixel ON / OFF
- Akronymus 1y agoOne thing with dithering writeups that always bothered me: There never seems to be coverage of how to calculate colour similarity when there are multiple different colours involved, rather than just black and white gradients. I am trying to implement it for myself, but really struggling to find any proper literature on that, that I am actually able to understand.
- mark-r 1y agoThe first step is to convert from the RGB color space to something more perceptual, like Lab. I'm sure there's a standard for comparing the color similarity of two images but I'm having trouble remembering the name - too early in the morning I guess.
- mark-r 1y agoThat was disappointing. I expected from the title that it would cover modern use cases. When's the last time you needed to use a web-safe palette? It's still useful if you're trying to display a 10-bit-per-channel image on an 8-bit-per-channel display, but the gain isn't nearly as dramatic. And the need doesn't come up very often.
- corysama 1y agoIt’s useful all 8-bit scenarios when you have overlapping transparency. Especially with smooth, dark images. https://loopit.dk/rendering_inside.pdf https://loopit.dk/rendering_inside.pdf The new Silksong apparently shipped with really bad banding that could have benefited from the techniques in that doc.
- magicalhippo 1y agoInside was pretty darn rad, very nice breakdown. They link to the following thesis: Optimal Dither and Noise Shaping in Image Processing http://hdl.handle.net/10012/3867 http://hdl.handle.net/10012/3867
- nixpulvis 1y agoWith high enough resolution does color depth become less important when you also dither?
- corysama 1y agoYep. You are trading special resolution for color resolution.