Video is Too Dark even after Brightening - How to fix with Avisynth?

[VideoFanatic]

Short MPEG2 sample HERE. Most of the time I can fix brightness issues easily however on rare occasions I get videos like this where even after raising the contrast, brightness, etc the video is still too dark. It's also like there is no detail in parts of the picture. I even raised the RGB levels to increase the brightness but it's still too dark.

Tweak (Hue=20, Sat=1.0 , Bright=10, Cont=1.2, Coring=False)

ConvertToRGB32(interlaced=true). RGBAdjust(1.6, 1.6, 1.6). converttoyv12(interlaced=true)

[Wolfen]

Have a look at this thread on brightness issues. https://forum.videohelp.com/threads/351530-Average-out-brightness

[manono]

Put on the Histogram and you'll see the problem. All the black is at 16 in a big thick line, and just below. There's no real dark grey or even much medium grey. The dark greys have already become black. If you keep good black levels, everything dark stays at black. If you increase the brightness too much, you'll lose all black and everything becomes dark grey. I don't know of a fix for that sort of thing.

What you did is about as much as you can, I think, except maybe for tweaking those especially dark scenes some more.

[sanlyn]

I even raised the RGB levels to increase the brightness but it's still too dark.

The code does brighten the image. Problem is, as manono explained, there is no data below a certain point. All you can do is make the crushed blacks a lighter gray. What you have is prime example of "crushed blacks".

[VideoFanatic]

I noticed with this video and a few others that when the contrast or brightness is raised yet the image still looks too dark apart from the mat which looks bright then I can't increase the contrast further otherwhise it would make the mat look too bright. But raising the RGB levels seems to be the only option for increasing the brightness without causing the mat to look too bright. I don't normally use high RGB levels like this.

What other option do I have to make the image brighter without causing the mat to look too bright?

[jagabo]

gamma

[sanlyn]

Your coded statement "RGBAdjust(1.6, 1.6, 1.6)" has a progressive effect. It is stronger with middle and high pixel values. It has little or no effect on the darkest pixels. 0 scaled by a factor of 1.6 is still 0. But RGB 100 scaled by a factor of 1.6 will raise it to a brighter pixel more than half its original RGB value. The brightest original pixels can get really bright.

To raise dark areas for a look at what's down there, use the RGB bias ("b") parameter, which adds values to pixels. 16 added to 0 = 16.
The statement RGBAdjust(rb=16, gb=16, bb=16) will raise zero-level blacks and all the other pixels by 16 RGB points. The "b" stands for "bias", or "offset".

Trying to work with RGB in a YUV scripting app is taking the rough road. Working with no histograms or waveforms on top of that is like groping along that road in the dark without a map.

[jagabo]

Start with something like this, tune to your liking:

ColorYUV(gain_y=75, gamma_y=200, off_y=-14, cont_u=200, cont_v=200)

[DB83]

I am missing something. But WHAT is the point of having your memberIDName changed ?

[VideoFanatic]

..

[sanlyn]

@jagabo, yep I was about to suggest something similar. And, yep, what's down there in the crushed darks is mostly the same noise I saw on my monitor.

[jagabo]

Yes, the darks are crushed beyond repair. And when you lighten the darks the macroblocking and posterization artifacts down there become visible. VideoFanatic will have to decide for himself how far he wants to go.

[mammo1789]

what about hdr agc in avisynth (or in premiere shadows effect) it is very simple and effective plugin especially for dark scenes.It works similar to HDR photoshop effect http://strony.aster.pl/paviko/hdragc.htm

[jagabo]

what about hdr agc in avisynth (or in premiere shadows effect) it is very simple and effective plugin especially for dark scenes.It works similar to HDR photoshop effect http://strony.aster.pl/paviko/hdragc.htm

It won't help. There are no details in the dark areas to restore.