Increasing Brightness of Videos (MP4 container)?

[meeshu]

I have some videos downloaded from YouTube. The problem is that some of these videos are just a bit too dark to see what is going on (clearly).

What is the easiest/best procedure to improve video brightness a little without making the videos too pale or washed out, I also understand that some noise reduction may also be required as part of the process(?).

Thanks.

[ProWo]

Use clever FFmpeg-GUI.
Increase brightness to 0.10 and encode a sample of 60 seconds to see the result.
You can also use the preview button.


[Attachment 85353 - Click to enlarge]

[jagabo]

In my experience there are few details in the dark parts of youtube videos. You'll be able to lighten some of the dark areas but there won't be anything there to see.

[meeshu]

Comments noted thank you.

Is there a means of setting the minimum brightness of videos rather than adding a fixed increase of brightness for all of the video? That is, I'm wanting to lighten dark scenes ONLY, leaving lighter scenes alone, and without having to cut out all dark scenes for separate processing(?)

[ProWo]

You cloud decrease the contrast.

[jagabo]

Yes, there are many ways of adjusting brightness. But what do you mean by "minimum brightness?" The darkest pixels in the frame? The brightest pixels in the frame? The average brightness of the frame? For example, you can use a gamma function (darker areas are made lighter, brighter areas remain the same) to bring out details in darker areas. Give a link to one of the videos at youtube.

[Selur]

I would first look at the video while applying Retinex to get a rough idea what details are there that could be highlighted.
For example:

gives a rough estimate of what I'm working with. (here are: some details, but also heavy blocking and artifacts inside the dark)
Then I would think about how to get to where I want with the source, assuming it seems worth it, and play around with the source.

After some quick evaluation, I would decide whether I try to brighten the source up.
Personally, I don't have much hope for dark content that was reencoded multiple times, but you never know unless you look at the content.

Cu Selur

[meeshu]

Yes, there are many ways of adjusting brightness. But what do you mean by "minimum brightness?" The darkest pixels in the frame? The brightest pixels in the frame? The average brightness of the frame? For example, you can use a gamma function (darker areas are made lighter, brighter areas remain the same) to bring out details in darker areas. Give a link to one of the videos at youtube.

Minimum brightness meaning there is a certain minimum level of brightness that areas/pixels of the entire video will not go below and where those areas/pixels are reasonably easy to see (most) details. So there shouldn't be any areas/pixels where it is pitch black with no details seen (excluding scenes where pitch black is intentional as part of the story/plot).

Sample video at YouTube here.

Other comments noted also, thank you.

[Selur]

More artifacts than details there:
Tweak+Retinex:







=> imho: not worth the trouble for stuff that is also available on DVD

So there shouldn't be any areas/pixels where it is pitch black with no details seen

that would only be true when your source was losslessly compressed and just the gamma was a bit low,.. highly compressed, low resolution, the compressor will throw out stuff it assumes will not be shown anyways.

Cu Selur

[jagabo]

Yes, there hardly any detail in the dark areas to bring out. A gamma adjustment brings out a little detail in those dark areas but they are grossly distorted and artifacted by the compression.


[Attachment 85379 - Click to enlarge]

I think you're better off leaving them black.

[meeshu]

Thanks for the detailed comments.

Some videos are not (readily) available on media (DVD, blu-ray) where I am. So for videos of interest, I have to find alternative sources to download.

Gamma correction does seem to work, but there seem to be issues with compression artifacts.

Is it possible to minimize compression artifacts? How?