blue screen chroma key question

little bird · Post by **little bird** » Mon Apr 30, 2007 3:08 am

Hi All,

Great Forum. Never thought I'd need to ask anything....however.....

I am working on a little blue screen/chroma key project. In anime studio pro I place picture of a car against a blue background (seperate layer) which i then output as an uncompressed AVI. (car is animated to look like moving across screen). I then place anime pro avi into adobe elements 2 and using the chroma key remove the blue background so that the anime footage on track 1 is superimposed on the dv-avi footage on track 2.

Problem is that when the vehicle picture (track 1) moves it has a very noticeable blue haze around the edges.

I would like to reduce or eliminate the blue haze and was hoping that one you guys can help out.

PC Quad proccesor, 2gig ram, 300g hard drive. (my brothers super computer......"to be used for REAL work only!!!") Yeah sure.

thanks,

Little Bird

heyvern · Post by **heyvern** » Mon Apr 30, 2007 3:40 am

If the car already has a transparent background or alpha in ASP there is no reason to use the chroma key.

Just render the car out into a format that supports an alpha channel (image sequence or mov format with alpha)

This should eliminate the blue halo when compositing.

You could also eliminate the whole step and render out from AS with the background you need behind the car.

If the car already has the blue screen as part of the image the halo problem is with Adobe Elements. The chroma key is not getting the edges of the blue because they aren't "exact'.

Does Adobe Elements have any way to modify the chroma key value? Adjust the falloff so it includes the edges of the blue that aren't 100% "blue"? Antialiasing causes that blue background to mix with the pixels of the car and produce a "nearly blue" edge that appears as a halo. This is a common problem using straight single value color replacement as a mask. You always end up with a "fringe".

-vern

little bird · Post by **little bird** » Mon Apr 30, 2007 4:02 am

thanks for your helpful response HeyVern. I'll try your suggestions.

It does however lead me to another question. For some reason I can't seem to import AVI into anime studio pro on the computer I am using. It works on my old laptop (very slow) and it did work on my old desktop. However on my brothers XPS quad processor all i get is a graphic where you would expect the avi file to be. The avi's work perfectly in other applications (media player, adobe etc). Also if I output an animation as avi from Anime then bring it back in to anime as an avi - woks fine. However the dv- AVI footage I capture using adobe elements does not work in anime. (thats why I have been doig the whole blue screen thing.)

I have checked the various settings against my laptop set up (in which AVI work) and they all appear to be the same as the desktop setup so I am at a loss to explain.

Please advise if you can.

thank you very much

Little Bird.

heyvern · Post by **heyvern** » Mon Apr 30, 2007 4:55 am

My only guess would be the format of the dv-AVI on this other computer is a format that ASP can't read for some reason.

Have you tried transferring AVIs from the other computers that worked in the past to this other one?

-vern

cribble · Post by **cribble** » Sat Jul 21, 2007 5:48 pm

If you can't solve the problem, just convert the avi's to mov format instead.

Mikdog · Post by **Mikdog** » Sat Jul 21, 2007 7:19 pm

There's a good tutorial that comes with the program for exporting AVI's with a transparent background, then re-importing them.

I think you leave the background empty, export as an Quicktime .MOV with whatever codec (Animation, Sorenson, etc...) with MILLIONS OF COLOURS +. This exports with a blank background.

Then, re-import it. It will ask you whether you want to import the .MOV with the mask. Say 'yes'.

The tutorial gives better details. Follow it closely. The example they use is of an exlposion animation.