Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Why do we need dithering?

typefully.com

Post reply on HN
Print view View original

101–110 of 115 posts

Re: Why do we need dithering?

#101

Post by lelanthran »

mark-r wrote: post #98
lelanthran wrote: post #87

Earlier quoted context omitted.

> The original Lenna is controversial, but I'm delighted to share the "ethically sourced Lenna": https://mortenhannemose.github.io/lena/ How is this ethically better than the original Lena - the model in that also one expressly approved the usage of the photo for the purposes it was being used for.

How did she expressly approve the original, when she didn't know for decades that it was so widely used?

> How did she expressly approve the original, when she didn't know for decades that it was so widely used?

Maybe I read the wrong interview with her, but when she found out about it she expressed happiness about it.

Since this replacement image was created after her interview, how is it ethically better in any way?

Re: Why do we need dithering?

#102

Post by christophilus »

ajb wrote: post #60
susam wrote: post #15

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. I think this is the original, photographed and contributed by Adrian Pingstone: https://commons.wikimedia.org/wiki/File:Parrot.red.macaw.1.a... But this particular derivative is the one that appears most often in the Wiki…

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 engra…

Malcom Guite’s new epic poem is illustrated that way: https://www.rabbitroom.com/merlinsisle

I love the look of it.

Re: Why do we need dithering?

#103

Post by dinkelberg »

lelanthran wrote: post #101
mark-r wrote: post #98

Earlier quoted context omitted.

How did she expressly approve the original, when she didn't know for decades that it was so widely used?

> How did she expressly approve the original, when she didn't know for decades that it was so widely used? Maybe I read the wrong interview with her, but when she found out about it she expressed happiness about it. Since this replacement image was created after her interview, how is it ethically better in any way?

Lena Söderberg expressed her wish for her image to be "retired from tech" in 2019 (see the end of this clip, https://vimeo.com/372265771), when the above alternative image was published.

Re: Why do we need dithering?

#106

Post by corysama »

mark-r wrote: post #96

That 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.

It’s useful all 8-bit scenarios when you have overlapping transparency. Especially with smooth, dark images.

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.

Re: Why do we need dithering?

#107

Post by kettlecorn »

mordae wrote: post #75
kettlecorn wrote: post #42

Dithering 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/valv…

It'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.

It 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.

Re: Why do we need dithering?

#108

Post by magicalhippo »

corysama wrote: post #106
mark-r wrote: post #96

That 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.

It’s useful all 8-bit scenarios when you have overlapping transparency. Especially with smooth, dark images. 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.

Inside 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

Re: Why do we need dithering?

#109

Post by vardump »

ant6n wrote: post #81

So, uh, why do we need dithering? I thought the era of 4 bit color had passed.

Dithering 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.

Re: Why do we need dithering?

#110

Post by jasomill »

kettlecorn wrote: post #107
mordae wrote: post #75

Earlier quoted context omitted.

It'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.

It 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.

Not so cheap if your hardware decoder only supports 8-bit color, which is a common limitation of H.264 decoders in particular.
Post reply on HN