Best Free Software To Brighten Underexposed Video

[NewTwoVideo]

I have some mp4's that are underexposed because the camera was trying to maintain balance between bright sky and dark surroundings.

What would be a good free software to use to brighten up the people and background even though the sky will become overexposed?

[Sharc]

I have some mp4's that are underexposed because the camera was trying to maintain balance between bright sky and dark surroundings.

What would be a good free software to use to brighten up the people and background even though the sky will become overexposed?

Avisynth is free. Try Levels(), Tweak(), AutoLevels(), AutoAdjust(), Retinex() (with a mask), or upload an example (few seconds) of your underexposed video so someone may take a look.

Some examples of exposure auto-corrections in this thread
https://forum.videohelp.com/threads/406406-Restoring-compensating-overexposed-heavily-...-s#post2662703
https://forum.videohelp.com/threads/406406-Restoring-compensating-overexposed-heavily-...-s#post2662888

[jagabo]

Try VirtualDub2 or AviDemux. You probably want to adjust the gamma or gain.

[Alwyn]

I second VirtualDub2 + Colormill. Colormill has separate adjustments sliders for darks, mediums and brights. Just what you want.

[NewTwoVideo]

Thank you, Sharc, jagabo, and Alwyn.

Looks like I have some experimenting to do.

I will post again with success, failure, or questions.

Many thanks.

[NewTwoVideo]

I have some mp4's that are underexposed because the camera was trying to maintain balance between bright sky and dark surroundings.

What would be a good free software to use to brighten up the people and background even though the sky will become overexposed?

Avisynth is free. Try Levels(), Tweak(), AutoLevels(), AutoAdjust(), Retinex() (with a mask), or upload an example (few seconds) of your underexposed video so someone may take a look.

Some examples of exposure auto-corrections in this thread
https://forum.videohelp.com/threads/406406-Restoring-compensating-overexposed-heavily-...-s#post2662703
https://forum.videohelp.com/threads/406406-Restoring-compensating-overexposed-heavily-...-s#post2662888

Sharc,

I already have Avisynth+ on my machine. Do I need to add Avisynth and can a person have both installed? Or will Avisynth+ do the same function?

[OS/Hardware info]
Operating system: Windows 10 (x64) (Build 26200)

CPU: 13th Gen Intel(R) Core(TM) i7-13700K / Broadwell (Core i7)
MMX, SSE, SSE2, SSE3, SSSE3, SSE4.1, SSE4.2, FMA3, RDSEED, ADX, AVX, AVX2
12 physical cores / 24 logical cores


[Avisynth info]
VersionString: AviSynth+ 3.7.5 (r4289, 3.7, x86_64)
VersionNumber: 3.75
File / Product version: 3.7.5.0 / 3.7.5.0
Interface Version: 11
Multi-threading support: Yes
Avisynth.dll location: C:\WINDOWS\SYSTEM32\avisynth.dll
Avisynth.dll time stamp: 2025-04-21, 03:08:56 (UTC)
PluginDir2_5 (HKLM, x64): C:\Program Files (x86)\AviSynth+\plugins64
PluginDir+ (HKLM, x64): C:\Program Files (x86)\AviSynth+\plugins64+


[C 2.5 Plugins (64 Bit)]
C:\Program Files (x86)\AviSynth+\plugins64\ffavisynth.dll [1.3.4533.0]

[C++ 2.6 Plugins (64 Bit)]
C:\Program Files (x86)\AviSynth+\plugins64+\ConvertStacked.dll [2025-04-21]
C:\Program Files (x86)\AviSynth+\plugins64+\DirectShowSource.dll [2025-04-21]
C:\Program Files (x86)\AviSynth+\plugins64+\ImageSeq.dll [2025-04-21]
C:\Program Files (x86)\AviSynth+\plugins64+\Shibatch.dll [2025-04-21]
C:\Program Files (x86)\AviSynth+\plugins64+\TimeStretch.dll [2025-04-21]
C:\Program Files (x86)\AviSynth+\plugins64+\VDubFilter.dll [2025-04-21]

[Scripts (AVSI)]
C:\Program Files (x86)\AviSynth+\plugins64+\colors_rgb.avsi [2021-01-11]
C:\Program Files (x86)\AviSynth+\plugins64\ffavisynth.avsi [2013-04-16]

[Uncategorized files]
C:\Program Files (x86)\AviSynth+\plugins64+\colors_rgb.txt [2021-01-11]


Thanks.

[Sharc]

Your Avisynth+ installation looks ok to me, so far. Your PC is much more powerful than mine. Avisynth+ is fine, no need to install legacy versions.

With your installation you should be able to run all so called "internal functions" including levels(), tweak() etc.

For more complex filtering tasks you will have to download the corresponding "external filters" (plugins) as required. These are usually .dll files or .avsi scripts. Download and unpack the 64bit versions of the .dll into your 'plugins64' folder.

If you have no or little experience with Avisynth+ this may all look a bit intimidating at the beginning - so start simple and experiment with basic filtering, like levels() and tweak(). There is a steep learning curve initially - but the reward is great.

The other proposals using Vdub2 or Avidemux are definitely simpler (GUI based) but won't offer the same power and flexibility as Avisynth. Maybe you can get away with these well known tools - I would just try. It depends on your source and ambition what is really needed and 'good enough' for your eyes

[NewTwoVideo]

Sorry, posts crossed in time.

Well, I tried installing AviSynth and it trashed my AviSynth+. So I uninstalled AviSynth and re-installed AviSynth+.

I installed Virtual Dub 2 and downloaded the Colormill vdf 64 bit plug-in and copied it to the Virtual Dub 2 plug-in directory.

I can run Virtual Dub 2, but even after selecting all of the video frames, I still do not see any menu entry about exposure or color.

Any help appreciated.

[NewTwoVideo]

I will try Avisynth+ as you described.

[NewTwoVideo]

I found the filters in Virtual Dub 2 and added Color Mill.
Now trying to clean up video.
I have a feeling I will be trying Avisynth+ also.

[davexnet]

Sharc meant the plus version in post #2 . It's not always mentioned explicitly because the vanilla Avisynth is so old now.
Installing the old version over the new is a terrible idea, no wonder it messed up.

On the other hand installing the plus version over the old works fine because the plus version's installer was written to handle that common scenario

[Darryl In Canada]

I'll write the minority report on this one...

I recommend Davinci Resolve to most people who want something free, easy, and good. If your files were lossless HuffYUV or Lagarith I would also suggest staying with a tool like VDub or using scripts. But if your files are already in mp4 (H264?) then just use Resolve.

[NewTwoVideo]

Thank you Darryl in Canada. I downloaded and installed Davinci Resolve.
Easy is a subjective term.
After doing some internet searches and figuring out how to import media and create timeline and find color page,
I find that the easiest way to alter to get faces visible in the underexposed video is to tinker with the curves graph.
So once I get to that point, I can get something usable.
I am not generating recreational content, instead I am trying to make documentation usable.
So, many thanks for that help.

If I may ask all one more question,
just after importing the video into Davinci Resolve before any modification, it looks way better exposed than when viewing it unchanged in VLC Media player. Why is that?

[Sharc]

If I may ask all one more question,
just after importing the video into Davinci Resolve before any modification, it looks way better exposed than when viewing it unchanged in VLC Media player. Why is that?

Different renderer (YUV -> RGB conversion, bitdepth, range, clipping ....) for the preview, maybe.

[Sharc]

I find that the easiest way to alter to get faces visible in the underexposed video is to tinker with the curves graph.

A nifty and easy to use gradation filter (with tutorial) is available for VirtualDub2 as well:
https://neosol.at/vdub/readme.html

Same/similar for Avisynth+
https://github.com/magiblot/gradation

Take note that these gradation filters are "static", means they don't "auto-adjust" along the timeline as some of the "auto-xxx" or Retinex Avisynth filters do. So one may have to adjust the settings manually scene by scene. Pro's and con's.

[NewTwoVideo]

I find that the easiest way to alter to get faces visible in the underexposed video is to tinker with the curves graph.

A nifty and easy to use gradation filter (with tutorial) is available for VirtualDub2 as well:
https://neosol.at/vdub/readme.html

Same/similar for Avisynth+
https://github.com/magiblot/gradation

Take note that these gradation filters are "static", means they don't "auto-adjust" along the timeline as some of the "auto-xxx" or Retinex Avisynth filters do. So one may have to adjust the settings manually scene by scene. Pro's and con's.

I will try these also.
There is a scene in a "Looney Tunes" animated short where Bugs Bunny is looking at the flight instrumentation and controls in an aircraft and it seems to him like miles of panoramic tech. That is how I feel when trying these programs. So many many options when I am just trying to make faces visible.