Good gamma correction?

[axolotls]

I shot some footage in a basically dark room. Very Dark..

If I play it with VLC, I can use their gamma control to bring out enough details to make me happy.

I used Vdub and all of the filters out there (levels, color restoration, gamma) and none of them achieved bringing out the faintest detail (they all acted like brightness/constrast filters).

Any hints (software or techniques would be appreciated). Thanks!

[redwudz]

Try 'Gradation Curves' with VD and you may get better results. I get best results with brightening overly dark scenes using it. Most times when you raise the gamma of a dark scene, you lose contrast and that filter can help there also. You can usually make the scene look better, but there is less detail in dark scenes that you can't really recover. The video may end up a bit grainy.

You might also need to up the color saturation or adjust the RGB levels just a bit, depends on what you have to work with. I use ColorMill II for those adjustments. It also has a level adjustment that can be handy.

I use those filters most often.

[jagabo]

The trouble with VirtualDub is that it converts everything to RGB for filtering. It does this with the rec.601 conversion matrix which performs a contrast stretch. That loses all detail in the blacker-than-black (and whiter-than-white) areas. So there is no way to retrieve it via VirtualDub's filtering. To get at that detail you need to avoid VirtualDub's RGB conversion, or adjust the levels before VirtualDub gets ahold of it. The best solution is to use AviSynth to open the file and convert to RGB with the pc.601 matrix which will avoid the contrast stretch. Then adjust the video in VirtualDub.

AviSource("filename.avi")
ConvertToRGB(matrix="pc.601")

Bit if you're using AviSynth to open the video you can also do all your adjustments in AviSynth and avoid RGB conversion completely.

There does appear to be one filter which works in YUV mode in VirtualDub. The Brightness/Contrast filter. If you use this filter first (adjust the brightness to ~+7 percent and the contrast to ~87 percent) you can recover blacker-than-black and whiter than white detail. Then use the levels (or other) filter to adjust the gamma. This may not work with all sources (some of the input plugins convert to RGB before giving the video to VirtualDub).

[axolotls]

Thanks. That explains the problem I've been having with the vdub filters. I'll try your suggestion with AviSynth (dang I forgot how to do that. it must've been five years since i used it!).

I fully expect the resulting video to be grainy and that will actually enhance the footage I am trying to bring out.

[axolotls]

Are they any other programs that can do this for me beside VDUB since it's not RGB source. Here's the info for the original file:

VideoStream 0:
CodecName: h264
CodecLongName: H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10
CodecTag: 1447904328 (HDMV)
Profile: High @ L4.0
Duration: 00:32:02.387
Start Position: 0.37s
Decoder Timebase: 1001 / 120000
Stream Timebase: 1 / 90000
Frames: 57614
Resolution: 1280x720p
Interlace: Progressive
Aspect: 1.778
PixelFormat: YUV420P
Framerate: 29.970
Max refs frames: 1
ID: 4113

[poisondeathray]

you can stay in the same colorspace if you use avisynth filters

you can try hdragc, smoothlevels ; read the instructions there are a lot of settings and configurability options

if you get stuck, post a sample of the video, and someone will suggest some treatment options and possible settings to use for the filters

[jagabo]

All you need is a simple AviSynth script:

DirectShowSource("filename.ext")
ConvertToRGB(matrix="PC.709")

You can create it with Notepad, just be sure to to name it .AVS, not .TXT. Then you open the AVS script in VirtualDub as if it is a video file.

[axolotls]

SWEET! That did the trick. I am now able to get a little detail out of the video (which is completely black when played normally).

Once I figure how to upload a raw sample. I will. I haven't done any of this type of stuff for years...

[jagabo]

If your video is AVI you can use VirtualDub in Video -> Direct Stream Copy mode to trim out a little sample:

File -> Open Video File
Video -> Direct Stream Copy
mark-in, mark-out
File -> Save as AVI

The mark-in point has to be on a keyframe (if you mark-in on a non-keyframe VirtualDub will start saving at the nearest keyframe before the mark-in frame).

You can upload files <30 MB here using the Upload Files/Manage Attachment button below the message editing box.

[axolotls]

Not even a second...

Original is MTS.

[axolotls]

Top screen is what you see if you play back the original file.
Bottom Screen is with the VDUB Filters using your AviSynth Script and MSU Filter.

[jagabo]

Pretty tough video. You might be able to squeeze a little more out of it with Neat Video noise filtering.

[axolotls]

Thanks. Checking it out now. How did you get the frame brighter? Any particular presets to try? The picture you posted is pretty much what I am looking for.

[jagabo]

I thought Neat Video would work better with an image that wasn't too harsh so I used two Levels filters, one before Neat Video and another after. The settings for the first were 0, 2.5, 32, 0, 255, the second 90, 1, 210, 0, 255. When in the Levels filter dialog you can use the Preview option to see a preview of the results, and the Sample Frame option to see a histogram (as a guide for setting the sliders). You should try variations of this to see if you can get better results.

You can also try disabling the "operate in luma instead of RGB" option of the Levels filter to bring out colors. You'll get mostly blues and magentas but you might be able to use the Gradation Curves to adjust the image to get something closer to the true colors.

Neat Video is pretty slow. If you're going to reduce the frame size of your video you should try doing it before Neat Video to speed up processing. On the other hand, Neat Video's processing might work better at the original resolution so you'll have to experiment.

[axolotls]

thx. been making test clips. will link soon.

[2Bdecided]

The clip you uploaded is RGB. I bet the original was YV12, so it's already been converted. It doesn't look like you lost much, but it's not a good workflow - especially when you intend to change levels.

Anyway, just try this...

avisource("aacc.avi")
#info()
levels(2,1.0,20,16,235,coring=false)
temporalsoften(1,255,255)
#converttoyv12(matrix="PC.601")
#histogram(mode="levels")

Cheers,
David.

[jagabo]

I believe his clip was RGB after ConvertToRGB(matrix="PC.601") so he could use VirtualDub's filters without losing blacker than black.

[axolotls]

http://www.youtube.com/watch?v=47YbmP62Gb8 (light noise filtering w/ sharpening) Test 4
http://www.youtube.com/watch?v=ZNas0x2d3nA (all the noise filters at max w/ no sharpening) Test 6

They seem to like the extreme fuzziness and yes, it's supposed to sound like that.

Any other tips? The samples were only done on 1/2 size xvids to speed up processing time (and still it takes quite a while to encode!!p). I am digging deep in the neatvideo advanced settings and confident i can get it to look at little bit better. It's similar to the Noise Ninja plug-in for Photoshop, except a little more tweakability.