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Comment by cogman10 | Hacker News Reader

> You especially notice the compression on gradients and in dark movie scenes.

That's not a correctly calibrated TV. The contrast is tuned WAY up. People do that to see what's going on in the dark, but you aren't meant to really be able to see those colors. That's why it's a big dark blob. It's supposed to be barely visible on a well calibrated display.

A lot of video codecs will erase details in dark scenes because those details aren't supposed to be visible. Now, I will say that streaming services are tuning that too aggressively. But I'll also say that a lot of people have miscalibrated displays. People simply like to be able to make out every detail in the dark. Those two things come in conflict with one another causing the effect you see above.

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> but you aren't meant to really be able to see those colors

Someone needs to tell filmmakers. They shoot dark scenes because they can - https://www.youtube.com/watch?v=Qehsk_-Bjq4 - and it ends up looking like shit after compression that assumes normal lighting levels.

As I said, I think the streamer services have too aggressive settings there. But that doesn't change the fact that the a lot of people have their contrast settings over tuned.

It should be noted, as well, that this generally isn't a "not enough bits" problem. There are literally codec settings to tune which decide when to start smearing the darkness. On a few codecs (such as VP1) those values are pretty badly set by default. I suspect streaming services aren't far off from those defaults. The codec settings are instead prioritizing putting bits into the lit parts of a scene rather than sparing a few for the darkness like you might like.

> Someone needs to tell filmmakers. They shoot dark scenes because they can…

i disagree completely. i watch a movie for the filmmakers story, i don’t watch movies to marvel at compression algorithms.

it would be ridiculous to watch movies shot with only bright scenes because streaming service accountants won’t stop abusing compression to save some pennies.

> …ends up looking like shit after compression that assumes normal lighting levels.

it’s entirely normal to have dark scenes in movies. streaming services are failing if they’re using compression algorithms untuned to do dark scenes when soooo many movies and series are absolutely full of night shots.

I feel like there are probably cinematic film-making tricks you can use to imply a very dark scene without serving #111 pixels all over the screen.

Video codecs aren't tuned for any particular TV calibration. They probably should be because it is easier to spot single bit differences in dark scenes, because the relative error is so high.

The issue is just that we don't code video with nearly enough bits. It's actually less than 8-bit since it only uses 16-235.

If an eye is able to distuinguish all 256 shades on a correctly calibrated display, then the content should be preserved.

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