thin black frame around a chroma green screen ...

kraz wrote on 5/24/2011, 6:16 AM
I assume my issue has something to do with aspect ratios off by a slight bit.
or my chroma settings

I have a graphic video that I made on top of a green background. that I saved an an mpg (dvd standard)

I imported that image into another show ... where I Chroma Keyed the green away and then the graphic after a while as the whole screen ... gets smaller and moves to a corner.

For some reason though - there is a very thin black line around the frame (prob 1 pixel all around) so instead of the graphic looking like it is just getting smaller ... it is shrinking with a frame around it ...

Any ideas or suggestions -

thanks
Allen

Comments

kraz wrote on 5/24/2011, 6:22 AM
I just answered my own question. And in case other have the same issue I will post it (instead of just removing the whole thing) - when I first learned vegas chroma Keying I got it from a great video tutorial (with the Charlie Brown theme in the background) and in that tutorial .. he said to first do medium chroma blur and then do the chroma keyer greenscreen. I never understood why to do the blur - but it worked well so I never challenged it.

well it seems that that blur is what caused my frame - not sure why .. but I just killed the Blur and lost that "frame box"

for curiosity - anyone know why to do the blur before? (does it help the green color be more constant?
Steve Mann wrote on 5/24/2011, 10:20 AM
Is the line the outline of your garbage mask?

Look at this:
http://www.sonycreativesoftware.com/forums/ShowMessage.asp?Forum=4&MessageID=721169
Rory Cooper wrote on 5/25/2011, 12:18 AM
A pre blur before you get your key will get rid of some digital data noise around the edge and reduce movement. the image scans horizontally so you will blur horizontally but only slightly if you add a vertical blur as well this will cause problems like you mentioned.

As Steve pointed out a garbage mask can be a real life saver for problem clips

Once you have keyed out the green you might need to choke/clean the mask if you don’t have BCC7 Alpha choker or matte cleaner etc then use your key as a mask on top of your clip add mask fx or add levels to choke or add secondary colour corrector select mask option and use smooth to choke/clean