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Video - dark edges


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#1 Ben Rollason

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Posted 04 May 2005 - 11:05 AM

I'm going to be doing a test next week on 35mm adapters for both mini DV and Digibeta cameras with regard to finding just how far lenses, grade, deinterlace and grain addition can go to overwhelming the inherent 'videoness' as compared to telecined 35mm. There is however one video artefact that I don't really know how best to deal with, or indeed why it occurs.

When you have highly exposed or over exposed areas along a sharply focused edge which is in front of a less exposed background, the sharp edge often appears to have a dark rim to it. The greater the difference in exposure, the stronger the effect. It's peculiar to video and seems to happen on all kinds of cameras from DV to digibeta SD to HD.

Here's two jpeg attachments - close ups of stills from an HD shoot demonstrating the effect.

hatrim.jpg
manrim.jpg

I've never seen the effct on telecined 35mm footage which suggests it's either to do with lenses or that the grain structure of the film minimizes the effect when telecined.

If you have suggestions about how you can reduce this effect, please let me know.

Regards,

Ben Rollason.
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#2 Phil Rhodes

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Posted 04 May 2005 - 12:08 PM

Hi,

Turn off the edge enhancement/sharpening/aperture correction/whatever.

Phil

Edited by Phil Rhodes, 04 May 2005 - 12:08 PM.

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#3 John Pytlak RIP

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Posted 04 May 2005 - 12:30 PM

Yes, it is edge enhancement. If you reduce it or turn it off, the "edginess" or "ringing" should be reduced, but so will the apparent sharpness.
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#4 Ben Rollason

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Posted 05 May 2005 - 05:55 AM

Thanks guys....that's really useful.
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#5 Stephen Williams

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Posted 05 May 2005 - 01:16 PM

I've never seen the effct on telecined 35mm footage which suggests it's either to do with lenses or that the grain structure of the film minimizes the effect when telecined.

Regards,

Ben Rollason.

<{POST_SNAPBACK}>

[/quote]

Hi,

I have seen this with telecine, but to a much lower extent. I always ask for the noise reducer and all sharpening to be turned OFF at the start of the transfer, I prefer to see what my film stock and lens choice have produced.

Stephen Williams DP
Zurich

www.stephenw.com
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