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blue/greenscreening problem

Posted: Sun, 2nd Nov 2003, 9:26am

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fertesz

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I wonder, how did You guys did that???
I mean, the part of greenscreen is almost white, when other is almost black, like his costume crazy
Currently, I'm making movie, and in some scenes I use bluebox, and I have same problem, even though it doeas not seem to be a problem in your case... biggrin
Now I started to manually paint bluescreen, but this is aLOT of work, and I fear it won't be as accurate as I would wish...
I'm using Magix Video Deluxe.
If someone can help, I would be most greateful wink
Posted: Sun, 2nd Nov 2003, 9:33am

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cantaclaro

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They used Chromanator...CSB's solution to compositing in and greenscreening...You can pull off no frills keys like that in seconds, according to CSB. Schwar says that the render times are about .05 sec per frame...which is extremely good. So get Chromanator when it comes out and you will be pulling great keys in seconds...

Canta unsure
Posted: Sun, 2nd Nov 2003, 12:56pm

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fertesz

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Yeah, perhaps you're right....
I'll most certainly think about it, but I don't have as much $$$ as I would wish.
Otherwise, I would have ALL filmmaking software available twisted twisted twisted twisted twisted
Posted: Sun, 2nd Nov 2003, 2:05pm

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Pooky

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That would be fun. And I was wondering what made chronomator so special till now... but now that I know, I have to buy it, and if I have to buy it, I need money, and this will mean I have to get an extra job during the summer... tard
Posted: Sun, 2nd Nov 2003, 3:26pm

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Illuminator

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It looks as though Chromanator might be a great tool. I look forward to seeing more about it.
I currently use the Serious Magic Ultra Key, and took the .jpg in this thread to see if I could get anything close... An example of the rendered can be found here:

Posted: Sun, 2nd Nov 2003, 3:47pm

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Joshua Davies

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Ultra Key is $795 - thats quiate a bit more than Chromanator.

Still it looks like we both give great quality keying tools. I'll have to check their demo (if they have one) - I doubt their animation and grading tools come close to Chromanator.

Maybe we should put the price up a bit wink
Posted: Sun, 2nd Nov 2003, 3:50pm

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AndrewtheActorMan

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no! heh
Posted: Sun, 2nd Nov 2003, 8:45pm

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neo_man89

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Chromanator will be great! I'm getting that and AlamDV3.....I can't decide if I should get DigiGrade also.
Posted: Sun, 2nd Nov 2003, 9:21pm

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Pooky

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I'm stupid so I don't get what digigrade is supposed to do...
Posted: Mon, 3rd Nov 2003, 2:30pm

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fertesz

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Uhm, funny, I just checked it with Magix Video Deluxe, and it seems, I've got great effect confused
Well, I suppose greenscreen is better than blue sad Maybe blue is darker?
Am I right?
Oh, and one more thing, schwar, that's not a good idea hugegrin wink
Posted: Mon, 3rd Nov 2003, 2:36pm

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Joshua Davies

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Have you got any of your blue screen images around? I could try them in Chromanator and stick up the results maybe...
Posted: Mon, 3rd Nov 2003, 4:29pm

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Coldfuse

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the digi grade tool, i think will be pretty sweet.

Like after effects plugins that i use. It will allow you to give a look to ur footage like minority repots. and also the colour levels of the matrix the blue and green i think... crazy

WILL be a nice tool i think and for the price. As im hoping it will give it that clean look i have been wanting. To take out grainy areas and also myabe improve levels. Just giving it a clearer look.. Thats what i think it is from what i have read maybe wrong.
Posted: Mon, 3rd Nov 2003, 4:35pm

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Coldfuse

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ive been talking to a friend. whos testin it at the moment. and i think people should buy this.

It seems very revoutionary to our type of community. the fact its at a reasonable price is even more of a reason to get it.

im pro getting chromanator. the fact youre gonna get amazing quality with ur dv camera footage.

actually a question to ask how do i clam my free alamDV3 program?
Posted: Mon, 3rd Nov 2003, 8:59pm

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Amadeus0

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In DV you Green screen due to the extra bandwidth on the green channel (in 4:1:1 compression Green has 4 times the color info, which will give a cleaner key.)

For film it's different. You generally want a blue screen due to the Lack of color channel info it takes up.

Note you can due blue in DV, and green in film (they did green for some parts of Titanic due to the blue outfits the crew were wearing.) If you do blue in 4:1:1 DV you'll have a harder time getting the key to come as clean as Green.
Posted: Mon, 3rd Nov 2003, 9:05pm

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Joshua Davies

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Thats not technically true. 4:1:1 doesn't represent Red, Green and Blue channels at all. 4:1:1 (NTSC) or 4:2:0 (PAL) is the sampling of the LUV channels. All colour information stored on DV equipment is fairly poor, hence the problems with blue and green screening on DV.

4:1:1 means there are 1 U and 1 V sample for every 4 luma samples meaning all colours are pretty much equally poor.

What is true is that CCD are green biased. The human eye sees detail in the green colour range better than any other. Around 60% of the detail we see is in green, 25% in red and 15% in blue. CCD makers know this so they put more green pixels on the CCD than the other two colors.

Even with this extra green detail the resulting image will still only be converted into U and V sampled every 4 pixels horizontally therefore making blue and green much the same when it comes to DV keying edges.

Last edited Mon, 3rd Nov 2003, 9:58pm; edited 1 times in total.

Posted: Mon, 3rd Nov 2003, 9:37pm

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Amadeus0

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I know, I know, I know. It's the 'simple' explaination.

The lum. is sampled every pixel, and red/blue are sampled every fourth pixel (every other when dealing with 4:2:2). When you put these 3 streams together you get the final picture. So there is more Green info/larger channel in a 4:1:1 picture, then blue.

What really causes poor keying on DV (green or blue) is the 5:1 intraframe compression. If you could get rid of that somehow, then with a 4:1:1 color space, Green would REALLY stand out (but also everyone would be getting better keys, blue or green.)

Also if you keep a YUV stream YUV during the keying process (instead of converting it to RGB as some programs do) the green screen will come out cleaner then the blue.

Which begs the question: Does AlamDV/Digigrade/Chromantor keep the video in it's native (usually YUV) form, or does it convert it to RGB?
Posted: Mon, 3rd Nov 2003, 9:56pm

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Joshua Davies

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DV's intraframe compression does indeed contribute to problems keying moving objects. Green information stored in the YUV format is more than that of the blue and red channels put together but it still suffers at the hands of the 4:1:1, 4:2:2 or 4:2:0 colour sampling. They will all suffer from poor edges without filtering, but its always going to be best to have as much information as possible there to start with meaning that green is the best followed by red then blue last. We do advise all Chromanator users to avoid blue screen as camcorders are pretting much biased against it from the CCD onwards.

As for Chromanator, all on screen display is in RGB (as you would expect) but otherwise it depends what key method you select. Chroma Key is RGB, Colour Difference Key is HSL (again as you would expect). Conversions made to create a matte (to HSL) only effect calculations for the matte, not the final image so retaining quality.
Posted: Mon, 3rd Nov 2003, 10:48pm

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Pooky

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woh... I'm lost... tard
Posted: Mon, 3rd Nov 2003, 10:50pm

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Joshua Davies

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If you're working with a DV camera then use green screen and a 3CCD camera if possible. Chromanator will do the rest.
Posted: Mon, 3rd Nov 2003, 10:58pm

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Pooky

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By the way, has beta testing of Chronomator started yet? AlamDV 3? If not, how do you join? biggrin
Posted: Tue, 4th Nov 2003, 3:53am

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Illuminator

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Regarless of all that has been said, based on the actual key that Chromanator displayed, and the cost, one can be sure that it will be a best seller. I can honestly say that I will most likely buy it due to the fact that it will probably more easily integrate with AlamDV2 and 3.

I look forward to it's introduction!
Posted: Wed, 5th Nov 2003, 5:00pm

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fertesz

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Hey, Schwar, I have two frames online cool
http://www.debce.republika.pl/kostek.html
You can find them on this site.
I'm curious of results with Chronomator biggrin
I know bluescreen is poorly set, but we had'nt much time redface
Next time will be better biggrin
Posted: Wed, 5th Nov 2003, 5:17pm

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Joshua Davies

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Neither would blue screen at all well. You first frame has black and white on the textured cloth. The second is just nasty compression. You should use green screen an at least hang it on a wall so it is smooth. Chromanator is really good, but it won't work miracles.
Posted: Wed, 5th Nov 2003, 5:19pm

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Simon K Jones

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Yeah, that isn't a bluescreen. It looks more like a tablecloth with a random bumpy texture to it. Bluescreens/greenscreens are supposed to be flat, smooth and matte. smile
Posted: Wed, 5th Nov 2003, 5:35pm

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fertesz

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Yeah, but I couldn't get anything better.
Still, could it work, if placed better?
Or maybe this texture makes it impossible? After all, Your greenscreen was partially black, and partially white.
What's the difference??
When I tried bluescreening with those images, they eventually gone 'invisible' ( biggrin ), but also small part of me did (on the edge of my figure).
Posted: Wed, 5th Nov 2003, 5:38pm

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Simon K Jones

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Chromanator can work with imperfect greenscreens, like in the Sollthar example. However, your bluescreen isn't even a screen, it's a big nobbly wobbly thing. confused

You could, however, still composite it in Chromanator, it just might take longer and require some manual work. The point of using a blue/greenscreen is to make the process quick and easy, rather than having to manually isolate elements of the shot - but you can't expect an automatic system to work properly if the raw footage contains so much random noise.
Posted: Wed, 5th Nov 2003, 5:42pm

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Joshua Davies

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One thing you'll notice is that our green screen is very green even if it goes bright and dark. Your blue is not only light and dark but also not that blue.
Posted: Wed, 5th Nov 2003, 5:48pm

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fertesz

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All right, so I suppose the proble is that I had textured 'screen'.
What's your solution to material? That was a blue sheet wink
Previously I tried with trash bags, but it was even worse confused
And now I will have a lot of work correcting those frames.... confused confused confused
Posted: Wed, 5th Nov 2003, 5:50pm

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Joshua Davies

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Rating: +1

Green cotton fabric. Use greenscreen with miniDV, not bluescreen.
Posted: Wed, 5th Nov 2003, 6:38pm

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fertesz

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Thanks! hugegrin