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Chroma probs with miniDV, need comp/grade help

Posted: Thu, 18th Jun 2009, 1:50pm

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taplinb

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Dear CompositeLab Pro wizards,

My half-time summer job is to do post-production in Final Cut on a professor's training video. I am a law student, not an expert in video dev, though I have done a number of home videos with good results and have used Final Cut's chroma tools with mixed results. CompositeLab Pro settings are easier to get right, but I am still having a hell of a time with color spill on two surfaces: gray hair, and black skin.

Please see sample clip Sample-1t.mov within http://www.cuibono.org/21C and I am sorry it's a large file. It's the shortest of a set of clips. Right-click the "filmstrip" icon to download, if so inclined.

It would be impossible to gather these subjects for a re-shoot, so we must make the best of it. A number of people important in my future profession have (unrealistically) high expectations. I have attempted to follow http://fxhome.com/forums/viewtopic.php?t=39552 to little avail. I do not yet have a blank matched backdrop still to use for color diff, but may be able to generate one. 200 hours of work-study, a tiny portion of which is for chroma work, is not enough to do roto work.

If this can be done but must be outsourced, please advise who could do it within weeks and at reasonable expense, and give a wild ballpark estimate of the cost per clip, if you could. I could then concentrate on motion keyframing, assembly, and title work.

Finally, if this is doable, how do I output to Final Cut? Tried once with the alpha channel box checked, but no luck yet.

Many thanks.
-Brad
Posted: Thu, 18th Jun 2009, 2:01pm

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Simon K Jones

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The link to the file doesn't seem to be working - I get a 'page not found' error. If you could fix that I'll take a look! smile
Posted: Thu, 18th Jun 2009, 2:06pm

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Axeman

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Rating: +1

If you remove the comma at the end of the link Tarn, it works.
Posted: Thu, 18th Jun 2009, 2:47pm

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Simon K Jones

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Yowch, that's a tricky one.

Here's an attempt I made to key just now:



And here it is again with light spill to further disguise some of the rough edges:



This was achieved using an Auto Color Difference key filter set to:

Automatic
-0.35
0.21
0.33

LOTS of freehand masks around the table and legs.

A Contrast:Pro grade filter set to:

12
256

And a spill suppression filter.

There are numerous major problems in the source footage, unfortunately, which make it pretty much impossible to get a good automatic key. Whichever way you look at it, you're likely to be doing some roto masking here if you want a good result.

I know you can't reshoot, but for future reference and anybody else reading, the main problems are:

1. The video quality itself seems very low. Is this the original DV footage from the camera, or has it been recompressed? There are some pretty severe artefacts on the greenscreen, a kind of cross-hatching, as well as around the black fellow's head, similar to high JPEG compression. I'm guessing this was shot on a relatively old miniDV camera, judging from the large, uneven black borders around the frame?

2. In addition to the cross-hatching the shot is also a little out of focus, which makes pulling a good key even harder.

3. There's lots of shadowing on the back wall, especially when the fourth guy enters and moves around.

4. The rear greenscreen intersects with the floor at right angles, creating a hard line and a much darker, shadowier area. The part of the floor up against the wall isn't really green at all and also has very low lighting - which is doubly unfortunate given that it's the area around the table and legs, making it very tricky to mask.

If this isn't the original and you have a higher quality source file to work from, you should be able to get better results. Otherwise, though, it's not going to be possible to get a professional comp out of this without extensive manual masking, as far as I'm aware.

Hope this helps somehow!
Posted: Thu, 18th Jun 2009, 3:39pm

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taplinb

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Thank you, Tarn (and others) for the work and the advice. I really appreciate it. Not sure where the original is, but I'll look. Meanwhile, if anyone has ideas about how much it would cost per minute of footage to outsource and get OK (not professional) results, like you just did here, that would help. Are you available, Tarn?

Meantime, I may also need to figure how best to get the output (with alpha) into Final Cut.

Here's another idea, which I will pose in another post here. Could I simply replace all green within the chroma range with a neutral gray (with a hint of brown and blue)? That is, forego alpha channels and change one color to something that would look good and accommodate titles? I prefer to avoid roto, given time constraints.

-Brad
Posted: Thu, 18th Jun 2009, 3:57pm

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Simon K Jones

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(no need to post another topic, it's best to keep it all here so people can find it easily, I've edited the name of this topic to better represent the issue)

How much video footage is there to be processed? This one clip is pretty short, but how much in total are we talking? It's unlikely I'll be able to do the work, I'm afraid, but if anybody else is able to offer their services they'll need to know what they're letting themselves in for. smile

Here's another idea, which I will pose in another post here. Could I simply replace all green within the chroma range with a neutral gray (with a hint of brown and blue)? That is, forego alpha channels and change one color to something that would look good and accommodate titles? I prefer to avoid roto, given time constraints.
That's actually a pretty good idea, and will vastly reduce the work required.

Here's a quick attempt:



The background can essentially be whatever colour you want. You're not going to escape the inherent low quality of the video source, but going this route is probably going to look better than actually trying to composite onto something else.

To do this I created two layers of the clip on the timeline.

The top layer I applied the same auto color difference key to as in my earlier post, as well as the spill suppression and contrast pro.

The bottom layer I didn't key at all. Instead, I applied a Desaturation grade filter to suck out all the colour, then used a Multi-colorize filter to add back in the browny tone. The Multi-colorize should be set up with 3 tabs, far left being black, far right being white and the middle being whatever you want as your background colour. Make sure you whack the filter up to full strength, too.

Thinking about it, Multi-Colorize might be a VisionLab-only filter, I can't remember off the top of my head.

Doing it this way will be a much, much faster job - once you've chosen your background colour you can just save it as a preset and apply it to all the clips (you'll need to have two layers for all of them still).
Posted: Thu, 18th Jun 2009, 8:59pm

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spydurhank

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Here's what I came up with.
As you know the video was pretty bad quality and I did what I could. Sorry I'm not as good as Tarn. Some of the clip can be saved or fixed but will take some roto work. I've been doing this kind of stuff for the past few months and figured out some short cuts or workarounds for speeding up the process of having to roto by hand or frame by frame so it's no big deal for me. I have plenty of free time and am willing to help out but first...

One or two questions though...

1. What is your deadline to have this completed?
As I've stated, I've got plenty of free time. The sooner you get back to me... the sooner it'll be done.
2. What kind of background are you going to use? This will affect the overall outcome. Is it dark or bright?
A bright background seems to hide any imperfections in the keying process as you can see in my render.

3. Are there more clips that you need to be worked on?
4. Do they have more complex movement than this clip?
This will affect the amount of time that it will take to roto.

Let me know what you think and try to give as much info as you can... by all means.
Oh and sorry about the purple shirts that used to be white. I had to play with the colors to get rid of the green spill on the people's faces and cloths.


By spydurhank at 2009-06-18
Posted: Fri, 19th Jun 2009, 8:42am

Post 8 of 16

Simon K Jones

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spydurhank wrote:

Oh and sorry about the purple shirts that used to be white. I had to play with the colors to get rid of the green spill on the people's faces and cloths.
Hm, the spill suppression filter should take care of it without needing too much in the way of colour distortion.
Posted: Fri, 19th Jun 2009, 6:50pm

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taplinb

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Thank you spydurhank, and again to Tarn, for looking at this. I must bounce the idea and color options off a marketing person for my school. I lean towards neutral gray with some teal, something dark enough that white text overlays would stand out, but we'll see.

As to assistance, kinda depends on the cost, as we are very tight, and moving gigabytes of footage over the Internet could be a problem, but I gotta finish a rough cut by the end of July. I will concurrently work on another part, using a generic backdrop (same color) with text rolling to the right and pictures dropping in on the left via motion keyframing. That stuff I'll do in Final Cut (I assume) and is beyond the scope of this discussion or CompositeLab Pro.

I'll get back to y'all.

-Brad
Posted: Fri, 19th Jun 2009, 7:28pm

Post 10 of 16

spydurhank

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You should be able to animate the text in Compositelab, I use Visionlab and it has the same features with a few extras. I was going to suggest that you do all the keying and text animation in Compositelab or Visionlab, that would cut down your workflow.

As far as assistance goes... My offer still stands, Don't worry so much about price... just let me know what you "can" pay. I can work for cheap but will do a good job. Apart from that it's good experiance that I'm after.
Posted: Fri, 19th Jun 2009, 7:41pm

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Axeman

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Nah, it'll be better to do the titles in Final Cut, where you can create them and animate them all in one go. Its certainly possible to animate them in CompositeLab, but it would require creating a title card for each title in a graphics application, then importing them into CompositeLab to do the animation. Final Cut's titling abilities are quite good.
Posted: Sat, 20th Jun 2009, 6:23pm

Post 12 of 16

taplinb

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Tarn, spydurhank, and axeman - you all rock! Being a newb, it took me a while to realize that I just right-click/copy my clip's title in the timeline and paste it, but once I got that Tarn's trick worked great. No need for multicolorize; Ambient light grading of the bottom layer after desaturation gave me my nice teal backdrop for text overlays. Many thanks, including to spydurhank who generously offered to help.

Is there a batch mode in CompositeLab Pro, or some other way to apply the same process to each of a hundred clips? I may automate some keystrokes, but every clip will otherwise require at least some human intervention.

I'll try to upload my presets if I can find how and where. Maybe just to www.cuibono.org/21C where you all would be welcome to snatch them and repost to www.FXHome.com as general methods for converting low-quality green-screen footage into something useful.

-Brad
Posted: Sat, 20th Jun 2009, 7:24pm

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spydurhank

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Dude that sounds awsome.
Can you post a photo of how Tarn's idea worked out for you?
That would be great. biggrin
Posted: Sat, 20th Jun 2009, 8:50pm

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Axeman

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There isn't really a batch control as such, but by creating a preset you can quickly apply the settings to whatever clip you want. Also, if you export all the clips from Final Cut as a single file, then you could process them all at once in CompositeLab, then bring them back into Final Cut and dice them up again. Of course, that would require that all of the clips involved need the exact same settings. If anything needs tweaked from one clip to the next, then working them individually is probably the way to go.

As far as uploading presets, its quite simple really. Export them from CompositeLab, then go to the presets page, scroll down a bit, and on the right hand side there is a "Submit a FXpreset" box with a "Submit" button. Click the button and navigate to your FXpreset_pack file is about all there is to it.
Posted: Sun, 21st Jun 2009, 3:06am

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taplinb

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Hey all,

Thanks again. I have uploaded "21C top" and "21C bottom" presets but neglected to describe them or add keywords. Tried to earlier today, but had to fix something and overwrote descriptions. Ouch.

The descriptions should say something about how used together with identical, layered copies of a lower-rez clip, they can turn the green into any other color without noticeably corrupting the subject or creating that halo effect that might otherwise require frame-by-frame rotoscoping. All credit to Tarn, of course, for the settings.

If anyone can find my two "21C" uploads and plug in that paragraph to each, or a variation, go for it. I just don't have time right now. For the output, see http://www.cuibono.org/21C/sample-1t-output.jpg

-Brad
Posted: Mon, 22nd Jun 2009, 9:37am

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spydurhank

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Okay...
I'm glad that you got what you needed but I'm a little confused right now.
Did you need the green background re-touched or fixed so that you could key it out!?
Or did you just want to change the hue to a neutral color but still have that same "textured" background?

Either way I worked on your clip for about an hour before I had to go back to work on another project that some folks and I are in the middle of, but I did get some very promising results.

I'll post a link to the work I've done on your clip in a day or so, once I'm done playing catch up with this other stuff. It pretty much involves cleaning up that horrid green background and the green spill on the people so you can get a better key. But if you already have what you need... then disregard this post.