Chromakeying vs Masking
 

Hi everyone,

Here's my question, I'm testing chromakeying for an upcoming project, here's the situation (look at the pictures) :

I'm filming a person in front of a greenscreen not wide enough (see picture CK-1)

I thought of going into the EVENT/ PAN CROP and reducing the width but this is what happened (see picture CK-2) notice the vertical lines on each side of the person

Then I thought of going into the EVENT/ PAN CROP and using the MASK option, but the same thing happened so I used the FEATHER TYPE option, set it to BOTH at 10% and this is what happened (see picture CK-3)

There must be something I'm not doing right.

Thanks.

Here's what I got:

Edward,

I'm using Vegas 7,

I could'nt open your VEG file.

Here's what I did (I don't have Vegas 7 on this machine and don't want to turn the other one on right now)

Track 1: Your picture
Track 2: Background image

On your picture:
1. Used Pan/Crop masking to create a mask around the girl with NO feathering. This let me see the background image outside of that area.

2. Used ChromaKey on the green area close to the girl. Had to adjust the high and low settings to get things to look right.

Edward If you read my first post that's exactly what I did, I used the feather option because It came out like this (see CK-4.jpg)

I think it's not a chromakey problem, I don't have any trouble adjusting highs and lows to get the look right.

I think it's a masking issue, If i remember right I already had this trouble masking on another project.

What version are you using Edward? could that be it?

Donald, it appears you've got a track motion shadow enabled, for starters? Or did you do that to better illustrate the key?
First, use the key to set your green. Then use the mask to cut her out. Be sure you don't have shadow on. Use the feathering both in/out.
We have a key that is too short for anyone much taller than 6', and have to often cut this, and have been using masking combined with keys since Vegas 5. I assure you, it works. But...you'll need to set the key first. Go ahead and key with the ugly sides. Then cut it out.
Make sure you're setting this to post, not pre.
HTH

Also, if you want to post YOUR VEG file, we can look at it to see where any issues may be.

Note that I haven't shot a chromakey yet, so anything I say is just from memory on what others have said or from what I see looking at your screen cap.

It looks like the subject is standing too close to the key screen and that the screen isn't hung or lit evenly enough. Some of the shadows on the wrinkles in the key are standing out.

When I tried my hand at the chromakey from your picture, the outside edge of her jeans too easily blended into the background because it was dark, as was that part of the chroma key cloth.

Like I said before jason, now I don't think it's a chromakeying issue, I already fixed the original problem (see CK_5) just by zooming in on the subjet and not having the need to mask because of the not wide enough greenscreen. But I still want to know why it happened.

I Had this problem before and there was no chromakey involved, just plain masking, An irregular line seems to apear around the mask (as you can see on CK-4 in my earlier post) the line is irregular.

I remember the last time this happened to me, I had filmed a field of white snow, and I wanted to mask out a dark rock in the middle of the field, so I masked it out, duplicated my track and chose the white snow on the side as background and the same thing happened, an irregular line appeared around my mask.

And to answer your question Douglas, no I did'nt add any shadowing of any kind in the track/motion section.

I should have had another Title to my original post "Masking problem" instead of "Chromakeying vs Masking"

Can you just post the VEG file? Then we can see exactly what you're doing and try to diagnose what setting is off.

Donald, try dropping a Chromablur on the event, and set it to "Pre" by toggling the little triangle in the plugin timeline head.
Set blur to 2.0.

If you still are struggling, do a framegrab PNG at Best/Full, email it to me, and I'll see if I can mask it for you.

You really shouldn't have to mask it, should you? If the green screen is evenly lit, subject is away from the green screen and casting no shadows, all should be good, right?

Question: When you cropped, did you ensure the aspect ratio was maintained?

I see the results, but I don't understand why it is effecting the image the way it is.

Could this be caused by the green screen being unevenly lit? (looking at the first pic)

I am very curious to find out what remedy was made....please keep us posted.

Good luck.

Masking can be necessary for any number of reasons, one of them being that he's got empty space behind the key that is in the shot. Another might be an unevenly lit key. Another might be that a boom mic fell into the shot.
Donald, did you try Chromablur yet?

Here's my VEG file
 

Ok guys, so I'm finally posting my VEG file so you can see for yourself.
The 2.7m WMV file wont load because it's HD, If you want it I can send it to you by e-mail, just let me know, that way you'll see exactly what I see...

Edward, sorry if it took some time I had to make another VEG file because I had alot of other stuff on it.

Douglas, I added the chromablur, anyways see for yourself!

Michael, I now think it dosent have anything to do with chromakeying, read my earlier post.

Thanks.

The veg without the content doesn't work. Can you upload or email a single frame grab as suggested earlier?

Douglas here's the new VEG files with the added JPG but the problem dosent show with a still, curiously the outlined mask shows only with a video. I can send it to you by e-mail it's only 2.7megs.

Move the Chroma Keyer FIRST in the chain. Or the Chroma Blur first and Chroma Keyer second. Put all the other effects AFTER those two. I did that on your original VEG file and the things that you're seeing totally went away.

Now... you still have the issue of black showing up above her head and below her legs but that's related to where the mask is located. However, just moving those two effects in the chain of effects clears it right up.

Ok so Edward figured it out!

The chromakey should always be first I guess, It was the Brithness and contrast effect that was outlining the mask.

It added some kinda shadowing around the women, I just adjusted the low threshold to 0.30 in the chromakeyer and voila.

Thanks Edward!

I did another test (see JPG) there was no chromakeying involved in this one, I copyed my original video file on to another track (track 1 & track 2 identical) deleted the chromakey and blur effect just for this test, I kept the brightness and contrast + color corrector + sharpen effects on both tracks at exactly the same settings, then I masked only the first track (without any shadowing), we can still see the masking outline, even if you change the order of the effects, the problem was fixed when I deleted all the effects.

So my conclusion to all this is that you have 2 options, 1- when masking you should never add any effects 2- render a file of the masking part without any effects then add it to the timeline and finally add the effects.

Wich to me seems like a major Vegas bug don't you think? by doing that I'd loose time and quality, what I don't understand is why nobody ever talked about this earlyer on this forum?

I did tell you to make sure that Blur/Keying are first. FX are ALWAYS added after a mask or key, regardless of what application you're using. Otherwise, you're asking the mask or key to process the FX, too. That's very hard to do. Color correction, FX, levels...all come after the key, never before. Chromablur and key first in chain (pre) and everything else comes after (post).
Whether it's Vegas, AE, MC, Premiere...It's all the same.
BTW, try to avoid brightness/contrast on video. Use Curves instead. B/C works on the chroma and luma, curves works on Luma and doesn't raise the apparent noise as much.

Thanks Douglas
 

Thanks for sharing your expertise, Douglas.

haha sorry Douglas! I just noticed it.

Thanks for the great advice Douglas, if I use the Curves FX instead of Brithness & Contrast will my mask outline show? (like the JPG in my last post)

As was said, place curves AFTER the key.

I agree that Brightness and Contrast really is NOT what you want to use. The other effects to a much better job. There's an entire discussion on Brightness and Contrast in another thread here from not too long ago. Here it is:
http://www.dvinfo.net/conf/what-happ...o-lighter.html