Error Diffusion Dithering - Computerphile 

...I think it's more likely that the two videos were just recorded on the same day.

@@totlyepic True, but the fact that he wore that shirt for both or each is still funny.

@Zero Cool Oh, I know. Either way it's funny to me, accidental or intentional.

It was probably in the audio of _this_ video :P

I'm definitely here for the audio dithering. There's an excellent Xiph video called Digital Show and Tell, that goes into what dither does for audio. But other than providing a sample code download, it doesn't really go into the how it's implemented.

Me too!

In color, you'd simply dither each of the color channels (red, green, & blue) separately. For higher bits depths, you just pick values for each pixel value. So instead of black (0) and white (255) for 1-bit, you'd have 0, 85, 170, & 255 for 2-bit. You'd use the same error diffusion after picking the nearest value. Technically, your values don't have to be equally spaced, and the formulae really should account for things like display gamma.

What a great idea, why didn't I think of that. Thanks.

It's also my relationship strategy. I don't return to the one I've already done.

Must be a crappy one. I can't work out what was the original image.

...or PCM (pulse code modulation), where the on/off edges are fixed, which can make some parts of the circuitry easier to manage, but the pattern of pulses is varied (basically a single-bit synchronous encoding of a number). That was how single-bit oversampling worked on many of the early "hifi" CD players, for instance, to move the quantization noise far enough out of the audio frequency range to make filtering easy using lower-order filters (which don't hurt teeth nearly as badly as "brick wall" high-order filter phase shifts).

or PFM

If keeping the size of a gif to a minimum is a major concern, dithering is your worst enemy :P

@@superscatboy True. Multi-meg gifs are rarely problematic these days though

There's a nice example at: caca.zoy.org/study/part6.html

Very true. It's adding high frequency noise and most compression methods attempt to throw out high frequency signals.

Seconded or rather, seventhed

nope, that leads to high frequencies, in audio dithering they randomize whether to round up or down so that the error is uniformly a noise

Never thought of that, but essentially yes.

Sounds like it yeah, but for each pixel in an image.

No.

humans perceive audio differently than images so Floyd-Steinberg isn't the best choice for audio dithering, randomizing whether to round up or down gives better results for audio

Lucas Pope (the author) did some additional work to make the dithering more stable under movment. He wrote about the technical details in a post on tigsource, which can be easily found through google by searching for something like "lucas pope dithering" #bayermatrix #bluenoise

There's a limited frame rate most display devices can use, so the benefits are less than you might expect.

space for train

sry bro. ly

First down vote.

This is extremely interesting.