ColourLike problem

[Cherbette]

Anybody have any ideas for something to correct the Chroma noise? Still got quite a bit of noise with removedirt+vd's built-in chroma smoother:

[sanlyn]

RemoveDirt didn't leave much to work with (not that there was much image in the first place), but here's the same filters and RemoveDirt v2 (right-hand image) at 4:3 ratio. I don't know, MCTemporalDenoise might clean those shadows a bit better, but. . .they're a little smoother now. The more detail that's removed, the closer we get back to clay-face.

[sanlyn]

I lowered saturation just a teensty notch in the image above. Yes, this is one badly discolored multi-gen dupe job. That lower mkidtone area is a hassle, but I've seen it before. Sometimes it never clears entirely (it can't. Once data gets destroyed, it don't come back). Each shot might have to be tweaked a bit. Very slight adjustments in RGB can make a big difference. But your colors are about in the ballpark.

VHS, especially when duped like this, often displays odd effects in some portions of the image. Small objects get discolored from chroma bleed from nearby objects. There's some bad edge ghosting, too (no surprise). You can use CSamp to check pixel values in tiny spots, then drag in another curves filter to address small areas. With damage like this, unfortunately, sometimes small bugs just won't give up. My guess about the small side view of Cher's face being discolored is that the bright-hand edge ghost from her hair is responsible. Time for me to learn masking and motion tracking in AFter Effects -- if I can ever get to it.

[Cherbette]

So would you advise against using removedirt since it's removing too much of the already lacking detail? lol

[sanlyn]

Say, what color is Cher's hair, anyway? Is it black, or just a really dark brown?

[sanlyn]

So would you advise against using removedirt since it's removing too much of the already lacking detail? lol

Up to you. You can give MCTD a try, I think it works less on fine detail at light settings and more on chroma. I believe jagabo has seen the source code for many of these plugins and likely knows better than I. MCTD did a nice job cleaning chroma on earlier posts, but those videos had much more detail.

[Cherbette]

Say, what color is Cher's hair, anyway? Is it black, or just a really dark brown?

It's a black wig lol

[sanlyn]

Yeah, I know about those famous wigs. I haven't watched her enough to tell which is which.

[magillagorilla]

I think any filter you try is going to remove some bad stuff add add an error because the footage is fragile. I would like to see Removedirt() > VDUB camcorder color denoise, and your color curves. You may be able to do a light sharpen to "unclay" skintones, but sharpening will exagerate some of those multi-gen composite errors at the edges of objects.

[sanlyn]

Anybody have any ideas for something to correct the Chroma noise? Still got quite a bit of noise with removedirt+vd's built-in chroma smoother:

Actually, it's not built-in. The script you're using calls two chroma plugins, but other scripts call different routines. The different plugins do different work in various stages of that script before RemoveDirt's main functions are called to clean up the results.

[sanlyn]

I think any filter you try is going to remove some bad stuff add add an error because the footage is fragile.

True. They're all destructive in some way.

I would like to see Removedirt() > VDUB camcorder color denoise, and your color curves. You may be able to do a light sharpen to "unclay" skintones, but sharpening will exagerate some of those multi-gen composite errors at the edges of objects.

I don't have the original AVI, I've been working with single-frame caps. So the VDub filters are really trial efforts on my end working with png converted to BMP in Photoshop. That, too, can have a variety of effects, so these filters are not The Final Solution to be applied to the original AVI. The VDub filter set is posted as an attachment earlier:
https://forum.videohelp.com/threads/340049-ColourLike-problem?p=2116299&viewfull=1#post2116299

Sharpeners likely wouldn't help, but some of the shots can "look" sharper by playing with the darker levels in the Levels control. IMHO Cher's hair in my v4:3 image post above is a tad bright.

[magillagorilla]

Cherbette, how about upping a sample clip. ... or is there one I missed? I just see screen shots. I may take a crack at it.

[Cherbette]

Sure gimme a few to get one up...

[sanlyn]

Rather than any sharpener, I tried lowering the darkest colors and the lower midtones a bit more. It gives the image a bit more punch, but with bad VHS you have to be careful with the extreme ranges. I also added a pinch of dark blue below RGB 20 because I thought the hair verged on turning a bit green, but those hair colors vary wildly. Cher's hair looks a bit more realistic, but her open mouth is turning black. The lack of detail doesn't help, either; more detail can hide a lot of color problems. With so little detail, bad colors are more obvious.



The "shadows" on Cher's fingertips fall into that low-midrange RGB area I mentioned. Look at how different the colors are in that area. Annoying.

[Cherbette]

Her blouse is pink and her undershirt is white...I think her nails are a metallic baby blue/teal-ish color.

Here is a 1 minute untouched segment:
http://www.megaupload.com/?d=39A8LEB0

I left this segment longer than I normally would see you get several different shots: one of Rosie close up, one of Cher close up, and a zoomed out shot.

[magillagorilla]

Sanlyn, that looks ok but you hace dulled the mid-highs in exchange for improving the mid-lows. I agree about the greening of the hair but I think it's a chroma noise\bleeding issue rather than a color balance problem. The chroma noise splotches are bothering me more than anything.

[sanlyn]

Gotcha, magillagorilla, but it's only one of several versions posted; example of what happens with different settings (which also made the background look less foggy). From the condition of the tape, we can only guess what that scene "really" looked like. It's not just chroma bleed, it's a chroma hemorrhage. Yes, those splotches are ugly. Those are the guys we're after. This is a multi-generational tape dub. We don't know how many generations. I have another bad capture on my PC -- even worse!

[magillagorilla]

"It's not just chroma bleed, it's a chroma hemorrhage. "

HAHAH!

Up a clip, I wanna play.

[Cherbette]

Her blouse is pink and her undershirt is white...I think her nails are a metallic baby blue/teal-ish color.

Here is a 1 minute untouched segment:
http://www.megaupload.com/?d=39A8LEB0

I left this segment longer than I normally would see you get several different shots: one of Rosie close up, one of Cher close up, and a zoomed out shot.

Clip is above

[magillagorilla]

Ohh right. My blindness. I'll give it a go later this evening.

[Cherbette]

haha...it happens to the best of us. It's hard to NOT lose track in a lengthy thread

[jagabo]

You can try sharpening the chroma channels with something like:

MergeChroma(last,awarpsharp2(last,depth=48)) #use on progressive material

But you'll find that small objects lose their color.

[sanlyn]

Mm, that's the biggest problem - the godawful grain in those shadows. If there was a filter that could smooth/degrain only a specific range (from about RGB 30 to 80), things would be peachy (already tried PeachSmoother). Smoothers work on the whole image, not just shadows. After viewing this clip 5000 times this A.M., I'm guessing that at some point during this video's dupe cycle (maybe about the 6th generation? ), somebody sharpened the hell out of this video - so there's ringing, even the ghosting is sharp, and bright detail simply exploded - not to mention some crushed blacks. I've been playing with smoothers/degrainers all morning. Still working. Color balance is pretty much solved.

There's some bad temporal noise, seen on the front of Rosie's desk and in streaks plus some kind of "flutter" in bright areas. I got rid of that with TemporalSoften and RemoveDirt - in that order; for some reason the two didn't work as well in reverse order. Looked even better with SeparateFields. Does that suggest something about an interlace problem at some point? I suspect so.

Streaks, flutter, rainbows and exploding streams of color gone. Now for that grain. Every time something moves, the whole place explodes with gnats and sparkles. Color blotching in shadows is on its way out, too. But those rough edges and sawtooth texture won't leave me alone for other work I have to do. Phooey. Going thru AviSynth filter lists now....

[jagabo]

You can always use Overlay() with mask based on the luma to smooth only dark or light areas. It's easy to smooth anything below a certain brightness or above a certain brightness. Filter only dark areas:

mask=ColorYUV(gain_y=800, off_y=-400).Invert() #build an alpha mask based on brightness, adjust gain_y, off_y to suit
Overlay(last, McTemporalDenoise(settings="very high"), 0, 0, mask)

I'd have to think about how to do it bounded between two levels.

[sanlyn]

Frame 354 from the original cap. It's within 16-235 in RGB (the darks are RGB 30 or higher). There's plenty of grain in the shadows on Cher's face and neck. But look at the black mouth. Lower the darks and the mouth looks worse - because there are no details in the midtones or brights. Cher's nose and other features have no detail, but what's there is just plain black. If you smooth those grainy shadows, you also smooth everything else. You end up with skull-head and clay-face effects.

[poisondeathray]

You can also probably do mask generation with masktools, I think there were some scripts on doom9 on how to filter a certain area of defined luminance. (Personally I think it's easier to do in other programs)

[Gavino]

You can always use Overlay() with mask based on the luma to smooth only dark or light areas. It's easy to smooth anything below a certain brightness or above a certain brightness. Filter only dark areas:

mask=ColorYUV(gain_y=800, off_y=-400).Invert() #build an alpha mask based on brightness, adjust gain_y, off_y to suit
Overlay(last, McTemporalDenoise(settings="very high"), 0, 0, mask)

I'd have to think about how to do it bounded between two levels.

You can also probably do mask generation with masktools

Yes, it's time you got into masktools, jagabo.
One of the most powerful and flexible items in the Avisynth toolkit.

For example, to create a mask of 255 between luma levels 30 to 80, and 0 elsewhere:
mt_lut(mt_polish("x > 29 & x < 81 ? 255 : 0"))

And to apply the mask, mt_merge is much more efficient then Overlay.

[jagabo]

Yes, it's time you got into masktools, jagabo.

I guess so. Can you feather the edges? Other than just using Blur?

[sanlyn]

You can also probably do mask generation with masktools, I think there were some scripts on doom9 on how to filter a certain area of defined luminance. (Personally I think it's easier to do in other programs)

Speaking of "other programs", I finally got myself an affordable copy of AE CS3 for my 32-bit XP . The wife apparently didn't think it was such a great price, she blew her stack for 3 days. Anyway, it'll take me a while to catch up with AE.

Yes, it's time you got into masktools, jagabo.
One of the most powerful and flexible items in the Avisynth toolkit.

Time for me too, gavino. I was just in doom9 looking at it. The idea has been been scaring me to death for years. Oh, well...I'll just keep looking. Hate to keep cherbette waiting too long for answers, but like the opera video I've just about finished, this clip is getting to be a real challenge.

[sanlyn]

The levels in the original cap are at least within a workable NTSC range (mostly). I seem to be having better luck playing with gamma in RGB (I did bring the gamma down in YUV to something easier to work with in RGB). For the time being I'll follow that path, but taking side trips into the other tools mentioned. Piece by piece . . .