Comment by knaik94 | Hacker News Reader

Comment by knaik94 | Hacker News Reader

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I'm not sure if it's because of growing up watching most things online with limited bitrates, but I realized I dislike film grain a lot. I know that to a certain degree, film grain helps humans resolve finer details. Similar to using noise shaped dithering to allow you to hear more than the theoretical dynamic range in audio or see a larger range of color tones in a picture. But I found that on certain 4K uhd blurays, if I am watching on a small screen the film grain looks very obnoxious. The problem doesn't exist when watching on a big TV, so I know it's not related to projecting on a screen. I really dislike when directors go out of their way to add artificial film grain. Will media players eventually allow users to adjust the film grain that is added back in?

This reminds me of Steve Yedlin's, cinematographer on everything from Brick to Star Wars: The Last Jedi to Knives Out and its 2022 sequel, Glass Onion: A Knives Out Mystery, who showed through research that film can be completely emulated using digital techniques and mixed digital and film shots during Star Wars.

https://www.audiocheck.net/audiotests_dithering.php

https://www.polygon.com/2020/2/6/21125680/film-vs-digital-de...

https://www.yedlin.net/NerdyFilmTechStuff/MatchLensBlur.html

https://www.yedlin.net/OnColorScience/index.html

>Similar to using noise shaped dithering to allow you to hear more than the theoretical dynamic range in audio

I’m not sure how apt this analogy is. Dither is only useful for mitigating artifacts of quantization noise; it does not generally increase perceived detail of any arbitrary signal. More specifically, it is introduced to reduce the harmonic content of quantization noise, at the expense of a higher overall noise floor. Suppose you have a 1kHz sine wave; quantizing it will introduce harmonics that peak at, say, an average of -70dB, with an absolute noise floor of -120dB. Adding dither will raise the noise floor to -90dB, but reduce the harmonic peaks to -100dB. So while it actually decreases the true dynamic range, it increases perceived signal quality by removing the harmonic content.

These spurious harmonics occur because quantizing a signal introduces periodic artifacts. For example, suppose our analog sine wave can continuously vary between 0-7, and we quantize it to 3 bits (discrete values 0,1,2,…,7). Any analog value 4.7 will always be rounded up to 5; in a sine wave, the value 4.7 will occur periodically, thus resulting in a periodic rounding artifact, leading to harmonic distortion.

In order to prevent these periodic rounding errors, dither needs to be added pre-quantization, so that 4.7 can sometimes randomly become 4.4 and get rounded down to 4 during quantization. Adding “dither” to an already quantized signal (e.g. digital video) would just make the apparent picture noisier.

As a test, try quantizing a full-color image to 16 colors, and then adding back some random noise. It won’t look any better. You need to strategically dither the 16 colors with knowledge of the original full-color image.

It's impossible to have a pristine signal when talking about film and tv. Having to transmit over wires and having to go from analog to digital will introduce quantization noise. Additionally raw capture and playback isn't an option because of transmission bandwidth limitations. And displays aren't in 12bit color depth, the most obvious visual example of poor quantization is color banding. While less obvious, film grain does the same for increasing the perceived texture. The quantization errors observable in video are different than in audio and I was trying to make an analogy that feels intuitive. I think the street picture in this link is helpful.

https://www.hdnumerique.com/dossiers/962-test-4k-ultra-hd-bl...

Film grain looks good until you hit a resolution (and color detail) that consistently exceeds the perceived boost that grain provides... which barely exists in pixelated screens in the first place. It provides some anti-aliasing and moire-reduction (at the cost of fuzziness), but that's about it.

When those smooth-then-pixelated-then-smooth lines transition to even-smoother, like 4K / HDR consistently hits, grain looks like the muddying noise that it really is.

I think it has more to do with the artificial boost in resolution not matching the “native” resolution of what the film grain would be in actual film.

Lots of stuff looks wrong with higher resolution and framerate, it’s not the thing (like grain) is inherently wrong, it’s just being done poorly.

Foley sounds and lighting are the things that annoy me the most about modern cinema. Those two characters looking into the sunset in the background… where exactly is the cool white light illuminating their faces coming from?

> Those two characters looking into the sunset in the background… where exactly is the cool white light illuminating their faces coming from?

The same place music in the film is coming from.

> cinematographer on everything from Brick to Star Wars: The Last Jedi to Knives Out and its 2022 sequel, Glass Onion: A Knives Out Mystery

Presumably, "Rian Johnson's cinematographer"?

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