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Fixing Chroma Artifacts?

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Continuing a laserdisc preservation, I have a capture with color artifacts.
Below are screen shots.
http://adventureclub.postrock.net/temp/1764raw.jpg
http://adventureclub.postrock.net/temp/4192raw.jpg
http://adventureclub.postrock.net/temp/5018raw.jpg

I've tried:
Cnr2("xxx",4,5,255)
GuavaComb(Mode = "NTSC", Recall = 75, MaxVariation = 25, Activation = 40)

But it mostly seems to wash colors out, with some slight improvement in later frames with interference artifacts (such as the pearls).

I tried color shifting but that doesn't seem to be the problem.

Any suggestions on this?

Dr. M

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Update: I just took a good look at the opening (laserdisc) logo (as opposed to the original one that's part of the film), and that lacks all of these chroma artifacts.

I guess this disc was a second tier release passed to some intern chimpanzee to do.
Sigh, I'll fix what I can, I hoped for some brilliant help to save the day.

Dr. M

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In my grand tradition of talking to myself in forums...

Here's the low down: avisynth's cnr2 and guavacomb are moderately successful at removing the color artifacts.
Many of these artifacts may be edge enhancement related.

Anyway, during fast motion some serious posterization occurs. It's rare, but so bad I can't use those filters.

I switched to VirtualDubMod's Chroma Noise Reduction filter and it work beautifully. It removes 80-90% of all the colors crawling along edges, interference in small textures, and overall improves the picture without softening it. The artifacts are few, far between, and absolutely tolerable in comparison.

This is the second time I've found VD's filters to be superior to the "recommended" avisynth equivalent (the other is Vdub's Levels filter vs. ColorYUV(off_y=0, gain_y=0) ). And I'm talking quality of output. Avisynth may have the edge on speed, but I'd rather encode slower and have better output.

So anyone else that needs to clean Chroma artifacts: try VDubMod's Chroma Noise Reduction Filter. I set YUV to wide and moved the U and V percentages to about 40%.

Cheers to anyone else that gets use out of the hours I spent toying with this. Screenies will follow (maybe).

Dr. M

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Hey there, I'm doing a laserdisc transfer and have this problem in the reds:

http://img99.imageshack.us/img99/5641/chromacrudcn0.jpg

Doctor M, is this anything like the probs you had?

I tried a slight chroma blur to minimize those vertical lines, but it never renders well.

One thing that *sort of* helps is a little de-saturation and slight hue shift, but—nah—the crap is still there. Does anybody know some specific technique that will fix this?

Dr M's above-noted steps are beyond me cuz I'm on a Mac; I'm using After Effects and some FCP plugins ...

Thanks.

(PS the disc is Ken Russell's Lisztomania)

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Uggh, that last example looks pretty bad. The poor contrast and blocky pixels look about as bad as those new digital flatscreen tv's. There's nothing any post production software can help you with because it seems your raw capture is garbage in.
So, how good is your laserdisc player? And what kind of capture device did you use. Laserdisc video is analog so having a good analog to digital converter is as important as the player. The other thing is to be sure you have a computer that can handle video with plenty of processing power, ram, hard drive and all those equipment things that I don't fully understand.

Take back the trilogy. Execute Order '77

http://www.youtube.com/user/Knightmessenger

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LD player is a Pioneer CLD-D504, into a Canopus ADVC-300; computer is all set ...

I only see the blockiness in the saturated reds ...

http://img171.imageshack.us/img171/6733/crud2uh3.jpg

P'raps I'm in denial ...
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Sorry the pics are down. If you COULD see them my problem was a kaleidoscopic rainbow on fringes around edges.
What you have is, oh I have no idea. The funny thing is it looks like a digital artifact.

I'm going to take a stab at this. You are going from your Laserdisc player to the Canopus ADVC-300 into your Mac?
I see that the ADVC has a lot of image cleaning and stabilization features. Have (can?) you play with them?

The problem looks very similar to what you can see in Cowclops' version 1 SW release.
He captured the video to digital tape and then into a PC.
Along the way, the color space changed. The digital cam utilizes 4:2:0 and DVD is in 4:1:1. The result is the worst demoniator of 4:1:0 which causes banding in solid red and solid blue colors, a lot like what you're showing.

I don't know if that's what your ADVC is doing (I'd hope not), but I'm just saying that's what it LOOKS like.

Dr. M

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Yeah, that would suck if the Canopus is simply screwing it up with digital whimsy.

I did about 10 test captures using various settings, only later did I capture the clip with the flames and noticed the problem.

I'll go back and do tests of just that section.

This is the control panel in question for the ADVC-300 with its default settings:

http://img207.imageshack.us/img207/7030/filter1qc6.jpg

I had the 3D and 2D NR off with y/c separation mid-hi—that's the comb filter, right?

Plus I have these to fiddle with:

http://img207.imageshack.us/img207/8268/filter2xw6.jpg http://img245.imageshack.us/img245/2880/filter3et5.jpg

That's my screen-cap quota for the day ...
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Yep, those blocky reds are clearly chroma subsampling artefacts (the Canopus captures in 4:1:1 DV format).

Does Final Cut Pro have a chroma smoothing filter?

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Yeah, there is a chroma blur filter which when applied very lightly works well on the still frame effect preview. When rendered, the blockiness is mostly still there.
That's frustrating. It looks like it's going to do just about exactly what I want, but—yippeee—just teasing, crap still there.

A similar chroma blur in After Effects works just as "well", probably both use the same Quicktime engine; maybe QT can't handle that color space well??

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Ok so now I'm curious. If it captures in 4:1:1 and DVD is 4:1:1 where are the subsampling artifacts coming from?

Are you capturing straight to mpeg2 or are you editing/filtering it and re-encoding it again?

Edit: So wait, are these screenshots a conversion to QT video?

Dr. M

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MPEG-2 is 4:2:0.

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Um, so wait, I got the problem right but the subsampling schemes reversed?

Dr. M

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Final Cut captures a QT DV stream .... I mean whatever the Canopus is outputting is grabbed, no conversion (not that I know of).

Definitely not capturing mpeg-2.

Those artifacts are in the raw DV.
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Ok, I thought all raw DV was the same, apparently the Apple codec gives steppy chroma edges ....
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Yep, NTSC DV has 4:1:1 chroma subsampling. MPEG-2 (DVD) uses 4:2:0. If you don't do any post-processing before encoding, you end up with 4:1:0 (which results in those horrible big blocks in pure reds).

Incidentally, PAL DV is 4:2:0 so doesn't suffer from this problem.

I'm not sure why the chroma smoother is not helping. Perhaps another option is to use a different DV codec that interpolates the chroma on decoding.

Maybe one of our resident FCP gurus (Jambe Davdar, ocpmovie, MoveAlong) could help?

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The chroma smoother works great in the still preview only -- maybe I have a rendering bug.

Anyway, here's what I tried:
I have a 'chroma>smooth-then-sharpen' filter, which, again, returns to blockie after it's rendered in the Final Cut timeline.

However, if I apply the filter, don't render, and instead export as 'uncompressed 10-bit 4:2:2', then put that clip through my mpeg2 encoder, I get this:

http://img172.imageshack.us/img172/9210/smoosharvi1.jpg

Not perfect, but much less blockie reds. The color change is from some desaturation I applied.

I guess this method bypasses Apple's DV codec ... I don't know ...

Is that silly to export as 4:2:2 uncompressed?
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Oh, I know why that's not a good idea, my exported movie would be 1G per minute.
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You might want to PM OCPMovie. I know he's a Mac-y.

Dr. M

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Will do, and thanks for the help.
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So:

If you save out an intermediate uncompressed file then use that as the source for the MPEG-2 encoding, you get the desired results. Do you have the disc space to do that?

But if you encode directly from the DV file it seems to bypass the filter chain, or it does not upsample the chroma (except in the preview).

I'm lost, I'm afraid.

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I'm lost, too! But that seems to be what's happening. The intermediate file is a smaller, 'pointer' file that references the original raw frames and whatever filters/edits have been set in FCP, but, and ....
— f*ck, I don't know!

I'll figure something out ...

No, I don't have the hard drive space.

Thanks for your help, guys, I'll keep you posted if anything comes of this.


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For chroma denoising, I found BiFrost and FFt3DFilter (especially FFT3DFilter) to be the best options.
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You need to avoid the MiniDV codec at all costs, if anything like that is going on at any stage.

I use the PhotoJPEG codec and that solves all my miniDV artifacting problems.