Damaged tape overexposed looking for minor improvements

[SkyBlues2021]

I have a couple of tapes that have some overexposed footage. I know any improvements I make will be small however, I would still like to try. I'm hoping to reduce the high contrast lines and reduce the brightness, anything else would be a bonus. I know there is very little detail to work with.

Sorry in advance for my crude scripts, I don't really know the best way to achieve the improvements. The SeparateFields().vInverse().Weave() seems to work well with the high contrast lines, jagabo used this in a previous script.

I wasn't sure of the best way to reduce the brightness of the pixels with ColorYUV() and Tweak() Any advice would be grateful.

[lordsmurf]

Restoration always starts with the best capture possible.

So what was the workflow?
- VCR
- TBC
- capture card

[Sharc]

@SkyBlues2021
You can't recover the badly clipped brights by lowering the brights level in post processing. What is lost is lost.
Is it a capture problem (levels, proc-amp settings...), or do the tapes look the same when you play them with your VCR connected directly (analog via S-Video or Composite) to your TV?

[SkyBlues2021]

Thanks Lordsmurf & Sharc. The tape is equally as bad when played directly to my TV. I incorrectly thought that you may be able to lower the brightness somehow, I knew I couldn't get back any detail in the video. I'm realistic and only hoped for small improvements. I feel the SeparateFields().vInverse().Weave() improved it ever so slightly? However I will have to live with the brightness.

[Alwyn]

Here's my attempt with Virtual Dub2 64, predominately using the Color Mill filter to adjust the low, mid and high "levels" individually with a bit of temporal smoothing. I've never found simple brightness and Contrast adjustments very helpful in this type of case.

[davexnet]

Regarding tape 12 overexposed 3 script.avi - I doubt if you'll get much better results in the bright end using
Avisynth, but you could darken the shadows a little to increase the contrast.

If you search the internet for this problem you see results for Davince Resolve, Lumetri, etc.

[SkyBlues2021]

Thanks Alwyn & davexnet. I will have a look at Colormill tonight your video looks better than my attempt. I've never used Color Mill before but will read up on it. When I searched the site regarding overexposed/blow whites I did read that someone had used Vegas, I'm guessing Davince, Resolve, Lumetri are similar software? I will also take a look at those tonight. Thanks.

[Alwyn]

Colormill 64bit details here:

https://forum.videohelp.com/threads/394653-Need-help-updating-Color-Mill-plugin-for-Vi...lDub2-to-64bit

[lordsmurf]

Again, the best restoration starts with the best capture.
So how was this captured? What gear?

If using a thrift store VCR, and an Easycap, that would explain the awful overexposure.

[Sharc]

Thanks Lordsmurf & Sharc. The tape is equally as bad when played directly to my TV.

Thanks. This eliminates the capture device or capture process as the culprit, and I don't think it is your VCR which causes the heavy overexposure, as other tapes play fine as far as I remeber, right? So the problem is most probably baked into the tape by the camera, unfortunately.

Added: Retinex with luma masking may help to mitigate the problem somewhat and restore a bit more details from the brights.
Stay tuned ....

[lordsmurf]

Thanks Lordsmurf & Sharc. The tape is equally as bad when played directly to my TV.

Thanks. This eliminates the capture device or capture process as the culprit, and I don't think it is your VCR which causes the heavy overexposure, as other tapes play fine as far as I remeber, right? So the problem is most probably baked into the tape by the camera, unfortunately.

I'd still hesitate to this conclusion, without facts about the deck. There's plenty of VCRs that react badly to the signal, and AGC goes stupid (over- or underexposed). Generally no-name brands, but not always.

[Sharc]

So here an attempt with Retinex. The brights are 'stretched' somewhat, see the waveforms. A little improvement perhaps .... (?)
https://github.com/Asd-g/AviSynth-Retinex

[Alwyn]

Not bad, Sharc.

[SkyBlues2021]

Thanks Alwyn, Lordsmurf & Sharc. Thank you for the Color Mill details I will read them now. Thanks Sharc for the Retinex video again an upgrade a definate improvement on what I have. I will watch it on my TV, it helps to be able to see both videos side by side and it looks better and less bright. I've heard of Retinex but I've never researched it, I will read that now also. All my other tapes are ok just these two, I think I had left some sort of backlight setting on, I'm really dissapointed with myself. The equipment I used to capture was Pinnacle 710, Datavideo tbc-1000 and Sony TRV120 camcorder. Thanks.

[SkyBlues2021]

Sorry Sharc. I didn't see the second retinex MP4 video, again it looks much better. I was just reading a previous post of your regarding Retinex using masks and a lot of filters. You also used convertToYV24() it looks a bit frightening! I need to read more to try and understand how it works.

[Sharc]

.... the Retinex video again an upgrade a definate improvement on what I have. I will watch it on my TV, it helps to be able to see both videos side by side and it looks better and less bright....

Your TV might refuse to play this side-by-side format. So here 2 rescaled variants which your TV should play:

[SkyBlues2021]

Thanks Sharc. I will watch the new video tonight on my TV and start reading more tomorrow and try and get my head around it. Thanks.

[SkyBlues2021]

I,ve added retinex to my plugins. I have tried to play with other people scripts to try and get a feel for it. I'm struggling to get GaussianBlur() to work I get an error message: gaussianblur unable to load libfftwf-3.dll! I've checked and I have a copy in both my SystemWow and System32 folders and the fftw3.dll. I've got the VariableBlur.dll in my plugins folder so I'm not sure what I need to do?

[Sharc]

Hmm, long time since I installed these libraries. Are you on windows 32 or 64? Did you follow the instructions here:
http://avisynth.nl/index.php/VariableBlur#Filters
I think the latest version is 3.3.10 from here:
http://www.fftw.org/download.html

If you don't succeed you could try any other strong blurring filter, for example something like
blur().blur().blur().blur()

[SkyBlues2021]

Thanks Sharc. I'm windows 64 bit. I use Avisynth+ 64 bit, the runtime dependencies I believe are the same as QTGMC which works fine. Looking through previous posts another member had the same error message. Thanks.

https://forum.videohelp.com/threads/406406-Restoring-compensating-overexposed-heavily-...eather-video-s

[Sharc]

You can obtain much the same "improvement" with something simpler like

smoothlevels(input_low=16,gamma=0.9,input_high=235,output_low=8,output_high=235)
smoothtweak(contrast=1.0,saturation=1.3)

as there is not much which can be recovered from the crushed and clipped brights.

[SkyBlues2021]

Thanks Sharc. I will use your code and post. I will persevere and try to get gaussianblur to load. I was pleased with the retinex video you did, it was certainly an upgrade on mine. I'm guessing you used gaussianblur in the code for your Retinex for TV video? If not I could try something else. Thanks.

[johnmeyer]

I got a little better result using the old Vegas over-brightening trick of inverting, then adjusting gamma upwards, and the inverting again. However, I didn't think it was enough of an improvement to post when I first looked at this, but since others have posted, I've shown a frame below.

Lordsmurf posted twice about needed a better capture, but I don't know why he keeps insisting on that. This got me to thinking: is there a difference in the final result between a video that was indeed overexposed, and one which was correctly exposed but then ruined by a capture card proc amp setting or VCR AGC circuit? I'd never heard of a VCR AGC circuit clipping highlights while maintaining the shadows correctly (which appears to be the case in these videos).


[Attachment 75700 - Click to enlarge]

[SkyBlues2021]

Thanks johnmeyer. Yes it looks better than my poor attempt. Your frame and Sharc's video post seem to make the blacks on my son's shirt darker and overall less misty. Do you then think I need to use vegas or capture again with different levels. To be honest these two original tapes had an incorrect setting on the camcorder, I didn't realise until a little later. I'm just hoping I can get something similar to what you have, but obviously I prepared to do anything that gives me a better outcome. Thanks.

[Sharc]

I got a little better result using the old Vegas over-brightening trick of inverting, then adjusting gamma upwards, and the inverting again. However, I didn't think it was enough of an improvement to post when I first looked at this, but since others have posted, I've shown a frame below.

John: Nice trick. In order to remove the horizontal stripes (e.g. on the boy's red shirt) I used:

Separatefields().Vinverse().Weave()

I have observed these horizontal stripes a few times before for PAL home videos. No idea where this comes from. A (SONY?) videocam oddity?

[Sharc]

Thanks Sharc. I will use your code and post. I will persevere and try to get gaussianblur to load. I was pleased with the retinex video you did, it was certainly an upgrade on mine. I'm guessing you used gaussianblur in the code for your Retinex for TV video?

Yes. Here the full script (I hope I remember correctly, a lot of parameters to play with):

AVISource("tape 12 overexposed 3.avi")
converttoYV16(interlaced=true,matrix="Rec601")
assumeFPS(25).assumeTFF()
separatefields().vinverse().weave()  #to remove the horizontal stripes
qtgmc(preset="fast") #deinterlace
clip=last
MCDegrainSharp()  #for denoising, or use your preferred denoiser

#retinex with luma mask:
lmask=clip.mt_binarize(threshold=100,upper=true).converttoYV12(interlaced=false).GaussianBlur(varY=2000.0).grayscale()    # mask based on luma
overlay(clip, converttoYV24(interlaced=false).MSRCP(fulls=false,fulld=false,lower_thr=0.0,upper_thr=0.0001,chroma_protect=3), mask=lmask)

#level adjustments
smoothlevels(input_low=20,gamma=0.8,input_high=235,output_low=6,output_high=245)
smoothtweak(contrast=1.0,saturation=1.3)

StackHorizontal(clip.turnright().histogram().turnleft().subtitle("  original deinterlaced"), last.turnright().histogram().turnleft().subtitle("  retinex with mask"))

#for x264 encoding:
convertbits(8)
converttoYV12(interlaced=false)

#return lmask  #for debugging the mask only
return last

[SkyBlues2021]

Thanks Sharc. I will try and get GaussianBlur working tomorrow. Everything seems to be in place for it to work. Thank you for the code, I will try and upload it tomorrow. I appreciate your help, sorry for being so high maintainance!

[johnmeyer]

Your frame and Sharc's video post seem to make the blacks on my son's shirt darker and overall less misty. Do you then think I need to use vegas or capture again with different levels. To be honest these two original tapes had an incorrect setting on the camcorder, I didn't realise until a little later. I'm just hoping I can get something similar to what you have, but obviously I prepared to do anything that gives me a better outcome. Thanks.

There is no need to get Vegas just to do this one thing. The solutions given by other people work just about as well, although if you already have Vegas, that is an easier approach.

If you have the original camcorder, and you can play the tape on that, look at the viewfinder. If it is bleached out there, then the original video was overexposed. Doing this eliminates any issues with proc amps, AGC and other possible problems in the capture train.

If you are asking whether you can get a better result by re-capturing the tape using different capture settings, if the problem is overexposure on the tape, there is no magic that the hardware can do which cannot be done better in software, so once you determine that the problem is just this particular tape, then your best bet is to do the best fix you can using software.


BTW, I still don't understand why some in this thread keep pointing to your capture system as the fault. If your hardware or settings were at fault, then ALL of your captures would be bad. If it is just this one tape, or just a few scenes on the tape, then problem is obviously the camera's exposure when the video was taken.

[SkyBlues2021]

Thanks johnmeyer. I will look at vegas as well. What Sharc did was better than I hoped for. I knew 20+ years ago I had messed up when I watched the tapes back. I think it was some awful backlight or sunlight button I had left on. I no longer have that recorder but I always knew it was baked into the tape. If I can't get my script working properly is it ok to ask questions on the videohelp site regarding vegas or would I have to go elsewhere? Thanks for the advice.

[johnmeyer]

Vegas has a learning curve and, of course, is a paid program. However, if you plan to do a lot of editing, it is a very efficient editing platform and well worth learning. There is a free download that you can play around with.

You can get help at the Magix forum:

https://www.vegascreativesoftware.info/us/vegas-pro-forum/

although I think you have to have purchased the product to get help. I used to post there daily and had over 10,000 posts before I left, because ... well, it's a long story.

Another place that used to have a lot of Vegas chatter was at Creative Cow:

https://creativecow.net/forums/forum/vegas-pro/