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video gets darker after denoising

Posted: Tue Mar 23, 2010 3:40 pm
by 21stcj
hey
i've denoised a lot of mp4 and m2t footage recently (via virtualdub and avisynth), and the output version has not only lost noise but also brightness.

http://www.henrikbauer.com/neat-unprocessed.bmp

http://www.henrikbauer.com/neat-processed.bmp

i guess a bit of brightness gets lost because the dirt has been removed, but i'm sceptical if theres also some lost in the process.

Posted: Tue Mar 23, 2010 5:25 pm
by NVTeam
> via virtualdub and avisynth

Perhaps there was something more than just noise reduction in that workflow?

Vlad

Posted: Tue Mar 23, 2010 7:08 pm
by 21stcj
no, nothing like brightness adjustments anywhere.
camera films dv avi, m2t or mp4 file.
import to vdub via avs, just 'directshowsource' and no extras
denoise to lagarith compressed avi video

then i imported the denoised and the source video files to vegas and had the result as seen in the pics.
i know that by removing the noise the video gets a bit darker cause the noise is bright by itself. but i got the impression that nv takes more away than it needs to. some areas are really getting too dark when denoised.

Posted: Tue Mar 23, 2010 7:52 pm
by NVTeam
NV itself does not modify the brightness of the image. It must be something else in that workflow in virtualdub and avisynth.

Please try the NV plug-in for Vegas, to see how it affects the original clip. You will see that the noise is reduced but brightness/contrast remain the same.

Thank you,
Vlad

Posted: Tue Mar 23, 2010 10:51 pm
by 21stcj
it doesnt affect the brightness, but it does affect the brightness...

like i said, it affects the brightness of the noisy parts of the video by removing the noise. maybe i just need to live with it, or raise the gamma value in the brightness plugin after denoising it. however its been something that confused me all the time, so i thought i'd mention it on this forum.

i wont switch away from virtualdub, cause you can lower vdubs priority. imagine denoising stuff for a month without being able to lower the cpu usage (like in vegas). i wouldnt be able to do anything else on the comp for the duration of the denoising, so i would need a second computer, one for denoising and one for editing.
thats why i love virtualdub for what it is.

Posted: Tue Mar 23, 2010 11:05 pm
by NVTeam
Why not just make a small test, to see whether the Vegas version of Neat Video will change the brightness of your original clip or not? Just in Vegas preview. I think it will not change it. I also think that VirtualDub and Neat Video alone will also not change it (in those noisy parts as well). If you can reproduce brightness change using either Vegas+Neat Video for Vegas, or VirtualDub+Neat Video for VirtualDub, please send me a test project allowing to reproduce the effect.

Thank you,
Vlad

Posted: Fri Apr 14, 2017 3:29 pm
by rsh
21stcj, I realise this is a very old thread but when typing in "neat video darker" in a google search, this thread is about the only thing that comes up on the topic... and I have a workaround for your situation.

I was at the end of a project and we filmed a few scenes in low light, so I started using Neat Video to reduce the noise for certain clips. Everything was fine until I saw a clip lose a lot of brightness. This puzzled me because it didn't happen to the other clips. Eventually I worked out that clips being linked to After Effects didn't have the dark issue.

So, I tried simply right-clicking on the problem clip, selected "Replace with After Effects Composition" and then dragged the Neat Video plugin over that on the timeline and, hey presto, no darkening issue.

I hope this helps... seven years too late lol.