This 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.<p>I think this is the original, photographed and contributed by Adrian Pingstone: <a href="https://commons.wikimedia.org/wiki/File:Parrot.red.macaw.1.arp.750pix.jpg" rel="nofollow">https://commons.wikimedia.org/wiki/File:Parrot.red.macaw.1.a...</a><p>But this particular derivative is the one that appears most often in the Wikipedia articles: <a href="https://commons.wikimedia.org/wiki/File:RGB_24bits_palette_sample_image.jpg" rel="nofollow">https://commons.wikimedia.org/wiki/File:RGB_24bits_palette_s...</a><p>This parrot has occurred in several articles on the web. For example, here's one article from a decade or so ago: <a href="https://retroshowcase.gr/index.php?p=palette" rel="nofollow">https://retroshowcase.gr/index.php?p=palette</a><p>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!<p>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.
The predecessor of dithering was the art of wood engraving, which reproduced the texture of illustrations in wood blocks used for printing in newspapers and books; necessarily in black and white. It's difficult to imagine now, but there was an entire industry of engravers to
many of whom solely practiced engraving of others designs (often supplied drawn directly on the block to be engraved, to save time). These engravers were highly skilled and the artistry with which a piece was engraved could make a huge difference.<p>For example see "A treatise on wood engravings : historical and practical", by John Jackson and William Chatto, 1839[1]; here is a quote (p585 of the linked edition):<p>"With respect to the direction of lines, it ought at all times to be borne in mind by the wood engraver, — and more especially when the lines are not laid in by the designer, — that they should be disposed so as to denote the peculiar form of the object they are intended to represent. For instance, in the limb of a figure they ought not to run horizontally or vertically, — conveying the idea of either a flat surface or of a hard cylindrical form, — but with a gentle curvature suitable to the shape and the degree of rotundity required. A well chosen line makes a great difference in properly representing an object, when compared with one less appropriate, though more delicate. The proper disposition of lines will not only express the form required, but also produce more colour as they approach each other in approximating curves, as in the following example, and thus represent a variety of light and shade, without the necessity of introducing other lines crossing them, which ought always to be avoided in small subjects : if, however, the figures be large, it is necessary to break the hard appearance of a series of such single lines by crossing them with others more delicate."<p>There was even a period of a few decades after the invention of photography, during which it was not known how to mass produce photographs, and so they were manually engraved as with artworks. Eventually however, the entire profession became extinct.<p>[1] <a href="https://archive.org/details/treatiseonwooden00chat/page/585/mode/1up" rel="nofollow">https://archive.org/details/treatiseonwooden00chat/page/585/...</a>. (This is the 1881 edition)
Unsurprisingly, macaw test images go way back. There is one in this old Kodak test image dataset that is often used in CG tests.<p><a href="https://r0k.us/graphics/kodak/kodim23.html" rel="nofollow">https://r0k.us/graphics/kodak/kodim23.html</a><p>It seems to have been uploaded in 1999 from an old slide dataset.<p>This seems to be the Photo CD from 1993. I suppose the source goes back earlier.<p><a href="https://www.math.purdue.edu/~lucier/PHOTO_CD/" rel="nofollow">https://www.math.purdue.edu/~lucier/PHOTO_CD/</a>
This also used to be a really common test image: <a href="https://en.wikipedia.org/wiki/Lenna" rel="nofollow">https://en.wikipedia.org/wiki/Lenna</a><p>But its apparently a cropped centerfold from Playboy
The original Lenna is controversial, but I'm delighted to share the "ethically sourced Lenna":
<a href="https://mortenhannemose.github.io/lena/" rel="nofollow">https://mortenhannemose.github.io/lena/</a>
What's the impetus behind replacing the image with something <i>even sexier</i>?
This 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.
Now I regretting leaving the machine vision field, I would love to use this picture in a paper xD
Oh my goodness that is delightful
It was shot by an actual Hooker, too.
And a poster of Lenna is on the wall of the Richard Hendricks character in the Silicon Valley series. Which makes sense as he's working on a compression algorithm.
I got a bit wave of nostalgia for my CorelDRAW experience. Thanks!
This was recently shared on HN: <a href="https://visualrambling.space/dithering-part-1/" rel="nofollow">https://visualrambling.space/dithering-part-1/</a><p>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.<p>- <a href="https://visualrambling.space/dithering-part-1" rel="nofollow">https://visualrambling.space/dithering-part-1</a><p>- <a href="https://store.steampowered.com/app/653530/Return_of_the_Obra_Dinn/" rel="nofollow">https://store.steampowered.com/app/653530/Return_of_the_Obra...</a>
Is 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!
Dithering 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.<p>Unlike the examples in this post, this dithering is basically invisible at high resolutions, but it’s still very much in use.
Another 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.<p>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!
A 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.<p><a href="https://en.wikipedia.org/wiki/Noise_shaping" rel="nofollow">https://en.wikipedia.org/wiki/Noise_shaping</a>
I 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.
I 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.
Also by the author: <a href="https://www.makingsoftware.com/" rel="nofollow">https://www.makingsoftware.com/</a><p>Recent discussions:<p><i>Making Software</i> - <a href="https://news.ycombinator.com/item?id=43678144">https://news.ycombinator.com/item?id=43678144</a><p><i>How does a screen work?</i> - <a href="https://news.ycombinator.com/item?id=44550572">https://news.ycombinator.com/item?id=44550572</a><p><i>What is a color space?</i> - <a href="https://news.ycombinator.com/item?id=45013154">https://news.ycombinator.com/item?id=45013154</a>
Dithering is super useful in dark scenes in games and movies.<p>By adding random noise to the screen it makes bands of color with harsh transitions imperceptible, and the dithering itself also isn't perceptible.<p>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: <a href="https://media.steampowered.com/apps/valve/2015/Alex_Vlachos_Advanced_VR_Rendering_GDC2015.pdf" rel="nofollow">https://media.steampowered.com/apps/valve/2015/Alex_Vlachos_...</a><p>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!<p>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
You 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: <a href="https://xcancel.com/chriswade__/status/924071608976924673" rel="nofollow">https://xcancel.com/chriswade__/status/924071608976924673</a>
This 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.
I 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.
The 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.
Can somebody explain to me how dithering is an aesthetic (as mentioned in the article)? I feel I'm too young to understand that
It'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.<p>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.
<a href="https://en.wikipedia.org/wiki/Atkinson_dithering" rel="nofollow">https://en.wikipedia.org/wiki/Atkinson_dithering</a>
<a href="https://shared.fastly.steamstatic.com/store_item_assets/steam/apps/410970/ss_e1c85315d608fc9ee27ed880ab941afbbaabd727.1920x1080.jpg?t=1708071592" rel="nofollow">https://shared.fastly.steamstatic.com/store_item_assets/stea...</a><p><a href="https://shared.fastly.steamstatic.com/store_item_assets/steam/apps/410970/ss_a50b04b27ad755d937f969ec7b7b91b853cf9a9d.1920x1080.jpg?t=1708071592" rel="nofollow">https://shared.fastly.steamstatic.com/store_item_assets/stea...</a><p><a href="https://store.steampowered.com/app/410970/Master_of_Orion_1/" rel="nofollow">https://store.steampowered.com/app/410970/Master_of_Orion_1/</a>
Even 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.
Earlier submission: <a href="https://news.ycombinator.com/item?id=45743067">https://news.ycombinator.com/item?id=45743067</a>
Something that really blew my mind, as someone who didn't study much signal processing: <a href="https://www.audiosciencereview.com/forum/index.php?threads/dithering-is-a-mathematical-process-not-a-psychoacoustic-process.11169/" rel="nofollow">https://www.audiosciencereview.com/forum/index.php?threads/d...</a><p>The tl;dr is that dither isn't just for the eyes, it's mathematically needed to preserve information when undergoing quantization.
What an insanely beautiful website. Reminds me of the golden days of the internet, remastered tastefully.
This is the best explanation I’ve come across. I enjoy dithering as a playful way to compress file size when it makes sense.
Slightly frustrating the author started out with color images and then switched to grayscale.
> Before we all mute the word 'dithering'<p>Is this a reply to something?
Yes, it's referencing a tweet which briefly made the rounds a few weeks ago:<p><a href="https://x.com/TukiFromKL/status/1981024017390731293" rel="nofollow">https://x.com/TukiFromKL/status/1981024017390731293</a><p>Many people believed that the author was claiming to have invented a particular illustration style which involved dithering.
So, uh, why do we need dithering?<p>I thought the era of 4 bit color had passed.
Playdead Games did a really nice presentation about dithering for games, it gets passed around and I'm sure it's been on HN already: <a href="https://loopit.dk/banding_in_games.pdf" rel="nofollow">https://loopit.dk/banding_in_games.pdf</a>
What's with the dithering trend? Why do I keep hearing about it everywhere at least once a week? Where did this originate from?
We really don't anymore.<p>Back in the late 90s maybe. Gifs and other paletted image formats were popular.<p>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.
<a href="https://en.wikipedia.org/wiki/Frame_rate_control" rel="nofollow">https://en.wikipedia.org/wiki/Frame_rate_control</a><p>Your screen likely uses dithering to produce 1-2 LSBs of each color channel of this piece of graphics right now.
We <i>absolutely</i> still need dithering; 24-bit sRGB is not nearly enough for a large monochromatic gradient to not have visible banding without dithering.
We've had a couple of other recent discussions on dithering: <a href="https://news.ycombinator.com/item?id=45750954">https://news.ycombinator.com/item?id=45750954</a> and <a href="https://news.ycombinator.com/item?id=45698323">https://news.ycombinator.com/item?id=45698323</a>. I commented specifically about the history of blue-noise dithering at <a href="https://news.ycombinator.com/item?id=45728231">https://news.ycombinator.com/item?id=45728231</a>.<p>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?<p>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 <a href="http://www.breakintoprogram.co.uk/hardware/computers/zx-spectrum/screen-memory-layout" rel="nofollow">http://www.breakintoprogram.co.uk/hardware/computers/zx-spec...</a>. 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.)<p>Occasionally in ZX Spectrum game videos like <a href="https://www.youtube.com/watch?v=Nx_RJLpWu98" rel="nofollow">https://www.youtube.com/watch?v=Nx_RJLpWu98</a> 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.<p>The Nintendo did something similar, but I think had four colors per tile instead of two.<p>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 (<a href="https://www.rtings.com/tv/learn/chroma-subsampling" rel="nofollow">https://www.rtings.com/tv/learn/chroma-subsampling</a> 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.<p>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.
They answered the question in the first two sentences: We don't need it, it's just an aesthetic nowadays.
Dithering 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.
Dithering 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.<p>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.
It's not just aesthetic, I keep seeing games with color banding because they don't bother to dither before quantizing.