chromakeying stuff in 1080p and exporting it

proximity

proximity

Well-known member
Does some one know how I could chromakeying stuff in 1080p using FCP (this part is easy), and then exporting just the keyed area, leaving transparency around this.(not so easy?) - Letting me import this into another application, like Motion?

- Prox
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I do not use FCP. Is it possible to save the keyed output as a targa 32-bit file sequence (24-bit image file with an 8-bit embedded matte file)? Alternatively, export the keyed sequence as a QT movie and then export the matte channel separately to be used with, say, a luminance keyer in Motion.

This is something I would do from a compositor, like Digital Fusion. I hope the concept is of some help.
 
You would need to set your timeline for a codec that supports an alpha channel; basically Animation or None. Animation at its best quality is about 1/3 the size of None and is essentially lossless. Then, render the timeline with the keying. Finally, export; I think "Quicktime Movie" would be the best because it's quicker, and it's not recompressing. It will be in the same codec that your timeline is set for. Then you can use this file in any program that can accept Quicktime (though I seem to remember having a problem with Combustion, maybe version 3; then you would export "Using QuickTime Conversion"). You will need to add .mov to the name for most programs, such as After Effects.

There is one problem with this approach, however: Animation and None codecs are RGB, so there is a YUV to RGB conversion. Motion and After Effects are RGB native, so sending a YUV file to them would go through this conversion anyway when you use it in these programs, but there may be an issue with gamma interpretation - the footage may become brighter in the mids, for example. Then you would have to bring the gamma back down.

The previous post about exporting the picture separately, and then the alpha or matte channel as picture information also works fine.

Verko
 
Verko said:
You would need to set your timeline for a codec that supports an alpha channel; basically Animation or None. Animation at its best quality is about 1/3 the size of None and is essentially lossless. Then, render the timeline with the keying. Finally, export; I think "Quicktime Movie" would be the best because it's quicker, and it's not recompressing. It will be in the same codec that your timeline is set for. Then you can use this file in any program that can accept Quicktime (though I seem to remember having a problem with Combustion, maybe version 3; then you would export "Using QuickTime Conversion"). You will need to add .mov to the name for most programs, such as After Effects.

There is one problem with this approach, however: Animation and None codecs are RGB, so there is a YUV to RGB conversion. Motion and After Effects are RGB native, so sending a YUV file to them would go through this conversion anyway when you use it in these programs, but there may be an issue with gamma interpretation - the footage may become brighter in the mids, for example. Then you would have to bring the gamma back down.

The previous post about exporting the picture separately, and then the alpha or matte channel as picture information also works fine.

Verko
Click to expand...

Thank you, this was very helpfull. - I'll try this. My plan is filming the head of some people in a bluescreen environment, then having just these keys into motions replicator, so that the heads can animate around the center of attention in advanced patterns.

Thank you again,

- Proximity
 
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