Rotoscoping query

3 replies [Last post]
Snake Plissken
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Joined: Sep 17 2000

I use adobe premiere for editing and occasionally save a sequence of frames as a filmstrip for Photoshop, and paint etc on the frames. However, I de-interlace the frames so I can work on the images clearly. Can anyone tell me if this decreases the resolution of the image? And when I transfer back to premiere, should I re-interlace the clip?

Alan Roberts at work
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Joined: May 6 1999

Yes, it will lower the resolution because interpolation takes place. Deinterlacing is one of the hardest things to get right, professional kit doing this properly costs thousands.

Whe you transfer back, the interlacing is automatic because your project is interlaced, you have no control over that.

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tom hardwick
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Joined: Apr 8 1999

But do we surmise that on re-interlacing (if we can call it that) the original resolution is not regained? It sounds as if the reduced resolution now becomes the norm, only it's interlaced to be displayed properly.

tom.

Alan Roberts at work
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Joined: May 6 1999

No, the original information is lost in the deinterlacing. When you return the now pro-scanned images to the project, I expect something as simple as dropping alternate lines will happen. The only way to find out for certain is to use a test signal, and I just happen to have exactly the signal you need. Look at my profile for a website, go there and extract the signal that I provided for measuring display gamma. It has information that is specific to every line (i.e. the two fields are very different. Try importing that as a still into video and it will flicker madly on TV. Export it to graphics and the deinterlacing will wreck that aspect of it. On reimporting, you won't get any of the flicker back again.

But try it and let us know what happens.