VHS Restoration

[Asesinato]

Woow i need that explained a little better n00b here

[jagabo]

Woow i need that explained a little better n00b here

What "that" are you talking about? The DeStripe filtering? Adjusting the video proc amp while capturing?

[Asesinato]

i use this to chanhe proamp settings direktly on the card and then i can see the changes live on virtualvcr preview when i hit save

[themaster1]

try to remove the auto gain option and capture at default settings, analyse with the histogram

[Asesinato]

auto gain is in sound????

histogram??? what do u mean?

[themaster1]

lol right, sorry

[2Bdecided]

I'd go back to defaults though - reducing contract if it's too much. Histogram = a histogram view in whatever program you're using to capture. I think jagabo has a better idea here.

"PICTURE PROC AMP - PLEASE READ INSTRUCTIONS" - there's a subtle hint right there!

Cheers,
David.

[jagabo]

In VirtualDub select Video -> Histogram. I also have to select Video -> Preview to see the histogram. Keep the histogram out of the red regions at the left and right*:



On my system I can't see the picture and the histogram at the same time. If I try to adjust the proc amp settings from within VirtualDub the historgram freezes until I close the proc amp dialog. So I use GraphStudio (or GraphEdit) to adjust the proc amp. That give me a live histogram while adjusting the proc amp. In GraphStudio I add the capture filter to the graph the right click on it and select Properties. That brings up the dialog with the proc amp settings.

* Sometimes there's a black border that's darker than the main picture so you can allow the historgram to extend a little into the red region. Or you can use the Video -> Crop feature in VirtualDub to crop away the edges of the frame leaving only the main picture. You won't see the result of the cropping in the preview window but the histogram will reflect be built from the cropped frame. Be sure to turn off the cropping before you capture.

[sanlyn]

In the histogram image shown above, the left-end and right-end will turn red when image data exceeds certain values. The left side is darks, the right side is brights. Notice on the far left-hand end, in the blue section there's a tiny blue "spike" at the very left end. That's usually the black borders of the image. It's okay for that to be in the red, it's going to be black anyway.

Now and then some of the image data might drift a little into the red. A little of it is okay, but if colors/lume start flooding into the dark or bright red end, those values will likely be crushed, losing detail.

[jagabo]

Now and then some of the image data might drift a little into the red. A little of it is okay, but if colors/lume start flooding into the dark red or bright red end, those values will likely be crushed and lose detail.

Actually, they will be crushed. The question is whether they are anything you care about. For example, black borders may be blacker than the main picture. You don't care of those black borders get crushed if it makes the main picture look right.

[Asesinato]

i dont have that histotogram in virtaildub?

[2Bdecided]

capture mode

[jagabo]

i dont have that histotogram in virtaildub?

It's in the Video menu while in capture mode.

[sanlyn]

To address the pattern noise, you can try Neural Net and/or Fan Filter
http://avisynth.org/vcmohan/NeuralNet/NeuralNet.html
http://avisynth.org/vcmohan/FanFilter/FanFilter.html

I spent half the day yesterday working with those suggestions, plus the DeStripe function and FFTQuiver. Will also try a script in German I found here: http://translate.google.com/translate?sl=de&tl=en&js=n&prev=_t&hl=en&ie=UTF-8&layout=2...manier&act=url (link is via Google Translate).
Been looking for links like this for 2 years. Might take a while, but I'm working my way thru. Thanks.

[themaster1]

@ Asesinato
I did some tweaking today for the capture2
http://imageupload.org/en/file/219366/new.jpg.html
original:
http://imageupload.org/en/file/219367/og.jpg.html
previous attempt:
http://imageupload.org/en/file/219370/previous.jpg.html

If you like it i'll give you the .vdf

[Asesinato]

I try tweaking alittle now, what do you think?

[Asesinato]

Og here is one from the bright area

[sanlyn]

You have to play with the values, especially thr, and sometimes using iterations with varying rad and offset work better, especially for fixed patterns that move

 . . .
AssumeTFF()
SeparateFields()

AddBorders(256,256,256,256)
Rotate(65)

DeStripe(rad=2, offset=2, thr=10)
Rotate(-65)
Crop(256,256,-256,-256,true) . . .

Got it working so far (Hm. Really softens somewhat, don't it?). I understand the bit about AddBorders and Crop when using Rotate(), and I know the working image should be mod-8 or mod-16. What is the figure "256" based on? Is it the original frame size (PAL) plus the rotate figure (65 degrees)? Or some other factor? I'm rotating 35 degrees with the dinner scene.

[poisondeathray]

Got it working so far (Hm. Really softens somewhat, don't it?). I understand the bit about AddBorders and Crop when using Rotate(), and I know the working image should be mod-8 or mod-16. What is the figure "256" based on? Is it the original frame size (PAL) plus the rotate figure (65 degrees)? Or some other factor? I'm rotating 35 degrees with the dinner scene.

Yes - the edges get cut off when you rotate . It just has to be mod 2 for separated YV12 fields. 256 was just a roough even number big enough that doesn't get cut off when rotated 65

Yes it's quite soft, that's why I called it a "brute force directional blur"

You can get more selective results if you know how to figure out the proper custom coefficients for the FIR filter like mp4guy (one of the avisynth gurus). He wrote that simplified function for dummies like myself - when it's used like that, it's just a vertical blur, but a bit more effective than a plain vertical blur using a box filter because it's honing in on some frequencies. I have no clue how to do the math for the proper method. I think it's the same idea for FFTQuiver or Defreq - you need to know the proper numbers

Read this if you want more info . (I asked about the method to get the #'s in that thread, but still waaay over my head)
http://forum.doom9.org/showthread.php?t=154863

As for the fan filter/neural net combo, I've never got that working either and you need to "train" it with a clean image.

[sanlyn]

Thanks, poison. I had little luck with the older plugins (FanFilter, etc.), thought I'd give mp4guy a try and FTTQuiver later. I'm getting a feel for DeStripe and sort of understand mp4's description of how the shorter version works. I get the theory, I still have no clue how he came up with the coded details.

Thanks for the other link. That sort of thing and masktools will have me busy for a while yet.

Ed: I found that if I do some very light denoise/sharpen before running DeStripe, detail holds up better. I mean start with easy going stuff, though, not to sharpen those lines at first. Then follow DeStripe with heavier guns.

[Asesinato]

I try tweaking alittle now, what do you think?

Anyone seen the new caps???

[jagabo]

I try tweaking alittle now, what do you think?

Anyone seen the new caps???

I didn't realize they were new caps (thought you were playing around with filtering). You still have crushed blacks.



The question is whether this is happening during capture or if it's recorded that way on tape (or something about the equipment). The former you can fix, the latter you can't.

[Asesinato]

What shold i try to change?? Contracts??

[jagabo]

According to Sanlyn, bring the Brightness setting up a bit. Try this: bring the brightness setting up until you can see that blacks are no longer black, but dark gray. Then post a few seconds of that dark dance shot. That won't be the correct capture settings but it will make sure we aren't clipping at the bottom.

On my capture card the black level is Contrast. Brightness is gain. Do whatever is necessary to bring the black levels up to gray.

[sanlyn]

Yes, jagabo is correct about Bright and Contrast on some gear and software. Here's the way it's supposed to work: Bright controls the black levels, Contrast controls the white (or brightest) points. But even Avisynth's own Tweak() utility doesn't work exactly that way! So you do have to fiddle a bit. But it doesn't take long to get a feel for the way a specific device is working. You do have to develop an eye for this stuff -- and it helps to know how to use histograms and waveform graphs.

I don't know what your tweaks were, but here are samples of what I'm seeing. I called thosse two captures "Capture1" and "Capture2_bright". Below is an image of your original dance scene and the way it shows up with no corrections. The ColorTools histogram tells the story: the luma (white graph at top) shows no midtones, suppressed brights, and a sharp wedge cutoff at the left end that indicates clipping of darks (lost detail).


Some work with various levels controls in Avisynth and VirtualDub. The histogram shows some midrange and raised darks. But there are still black "blotches" where detail can't be raised any higher withjout making everything look washed out. This is why you try to keep your darks and brights within a certain range during capture - and never use auto-gain during capture. It almost always does exactly what you don't want. That range might look variable from scene to scene, but you can always adjust later in software.


The second capture of the brighter scene seems to have some odd adjustments going on and the same cutoff wedge at the left. This time the lowe levels are too low and the brighhts are still depressed, so you have what looks like a grayed-out image. For the right-hand image I adjusted everything only with levels controls to balance the darks, midtones, and brights. The only color was adding a small touch of blue to the bright end. I think you can see how just adjusting levels alone can affect your perception of an image.

[Asesinato]

i tried some tweaking and capped 2 clips, but now its seams to **** totally op

[Asesinato]

here they are

[sanlyn]

When you say you "tweaked", exactly what do you mean? Your card's proc amp settings? VirtualDub or Vvcr capture settings?

[jagabo]

The black level is even more crushed than before. And now the whites are blown out too.

[sanlyn]

Give us an idea of what you're using for tweaks. Which controls and settings? I think the last two caps, you're trying to color correct. For now, focus on the levels. Usually, single-slider Hue or Tint controls are difficult to use for color work, and they affect levels as well.

The original colors on the tape aren't that far off. The dance and dinner scenes, for instance, with that type of lighting you have to expect a little more warm colors, but they need adjustment. Look at the dance scene images I posted earlier, and the outdoor shot; notice how the perception of color changes after the darks, midtones, and brights are balanced, with little or no actual color adjustment controls in use. It's best to get your darks and brights within the histyogram limits; colors that are clipped or blown away can't be changed, they're just gone.