10bit to 8bit produces a way darker look

General questions or discussion about HandBrake, Video and/or audio transcoding, trends etc.
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eusi
Posts: 46
Joined: Sun Jan 26, 2014 9:55 am

10bit to 8bit produces a way darker look

Post by eusi »

As the title says, I want to convert a 4k (10bit, HDR) HEVC video into a 2k (8bit) x265 mkv one.

I did this with Handbrake by only changing the dimensions (width/height/cropping).

Since I have the same video also recorded as 2k (but with lower quality) I am able to compare the results.

Result/Issue:
The transcoded one (4k to 2k) looks way darker than the original one.

Question:
Do I need to correct somehow the colors (obviously they change from 10bit to 8bit on a not expected way)?

Thanks,
eusi
Deleted User 13735

Re: 10bit to 8bit produces a way darker look

Post by Deleted User 13735 »

Logs are required for support.
rollin_eng
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Re: 10bit to 8bit produces a way darker look

Post by rollin_eng »

Could you please post your HB logs, instructions can be found here:

https://handbrake.fr/docs/en/latest/hel ... y-log.html
eusi
Posts: 46
Joined: Sun Jan 26, 2014 9:55 am

Re: 10bit to 8bit produces a way darker look

Post by eusi »

Oh, sorry, thought it may be a general issue.

Here is the log:
https://pastebin.com/guTHtPpR

If something else is missing, please let me know.

Thanks!
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Ritsuka
HandBrake Team
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Re: 10bit to 8bit produces a way darker look

Post by Ritsuka »

Your source is HDR, if you want to play it on a player that doesn't support HDR, you need to enable the colorspace filter and set it to Bt.709.
I assume your 2k version is not HDR. Movie studios do a different color grading for HDR and SDR, so they won't look the same anyway.
eusi
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Joined: Sun Jan 26, 2014 9:55 am

Re: 10bit to 8bit produces a way darker look

Post by eusi »

Ritsuka wrote: Sun Mar 21, 2021 2:32 pm Your source is HDR, if you want to play it on a player that doesn't support HDR, you need to enable the colorspace filter and set it to Bt.709.
I assume your 2k version is not HDR. Movie studios do a different color grading for HDR and SDR, so they won't look the same anyway.
Yea that makes sense, thanks!

However, I just tested it via "live preview". The colors in the 10s preview still look darker. Actually I tried to change the colourspace to the other that are available as well. No difference in the rendered preview. All look identical. Am I doing something wrong?
eusi
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Joined: Sun Jan 26, 2014 9:55 am

Re: 10bit to 8bit produces a way darker look

Post by eusi »

Here some example images of the video:

Source 2k (8bit, BT.709):
Image

Source 4k (HDR, 10bit, BT.2020) to 2k (8bit, BT.709) transcoded:
Image
eusi
Posts: 46
Joined: Sun Jan 26, 2014 9:55 am

Re: 10bit to 8bit produces a way darker look

Post by eusi »

I guess this topic is obsolete.

I just found this: oversaturated dark areas playing HDR 10 bit
People reported here that HDR 10bit shows a darken/desaturate video, when they use the newest IINA video player.

Actually I have the same issue with VLC (e.g. compared to MPC).
Obviously those players interpret the color differently (I guess its the tone mapping algorithm).

So, it looks like that it has nothing to do with the transcoding or Handbrake. *thumbs up*
damian101
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Re: 10bit to 8bit produces a way darker look

Post by damian101 »

That has nothing to do with the bit depth, color space issues would also not make the image significantly brighter or darker.
The issue is definitely HDR. The problem is that there is no "correct" way of to convert HDR to SDR.
From my understanding HDR video isn't much different from SDR video aside from having metadata that tells the decoder at what 100% brightness the video has been mastered. If you have an HDR monitor the decoder knows how bright your monitor can be and just increases brightness of the video to match it (resulting in loss of image information in the bright parts), or maybe the monitor does that, don't know. Anyway, the same thing would need to be done by an HDR to SDR conversion filter, you would set the target brightness in Nits (something between 250 and 400 Nits would be reasonable since the brightness of most SDR monitors lies in that range), higher value meaning more image information in the bright parts being preserved but also making the video darker. I wonder if something like that exists. Of course the HDR metadata would also need to be removed when using that filter.
Using some automated "Fake HDR" filter, or maybe just changing gamma value might actually give you more visually appealing results though because more information in the bright parts is preserved, but it wouldn't accurately represent the dynamic range and brightness differences of the original video.
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