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Levels change when using Witness Protection

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Lee BergerLevels change when using Witness Protection
by on Jun 20, 2007 at 4:45:41 pm

I've been using the Witness Protection filter in Boris Continuum 4.0 for FCP 5.1.4. It works very well except for a change in levels when the effect is applied. I split the clip (using the razor tool) isolating just the portion of the clip where a face needs to be hidden and applying Witness Protection to that portion. The problem is that the video level changes between the filtered and unfiltered portions of the clip. It looks as if the Boris filter is clamping the video. I particularly noticed it in a shot with a hot sky, but looking back at other clips it's there as well. Any suggestions?

Thanks,

Lee

Lee Berger
http://www.leebergermedia.com


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peter mcauleyRe: Levels change when using Witness Protection
by on Jun 21, 2007 at 2:07:26 pm

Hi,

I've been trying to replicate this but can't seem to see the difference that you are seeing. What effect method are you using? And within what host environment / platform?

Thanks,

Peter.



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Lee BergerRe: Levels change when using Witness Protection
by on Jun 21, 2007 at 3:27:55 pm

Peter,
Thanks for responding.
[peter mcauley] "What effect method are you using?"

I'm not sure what you mean by effect method.

[peter mcauley] "And within what host environment / platform?"

I'm using Final Cut Pro 5.4.1. and Boris Continuum 4.0 filters. It doesn't make any difference if the effect is rendered on not. I tested a few other Boris Filters (page turn, lens flare) and the same thing happens. Video is clamped to 100 IRE. This wouldn't be a big problem if I was applying to an entire chip and not trying to match frame to the split portion. The problem does not occur when applying FCP or other third party filters.

I'm monitoring analog using AJA IO and a Tektronics Waveform Monitor.

Interestingly enough when I tried to export a couple of example frames to post both frames were identical in level, clamped to 100 IRE. As a workaround I exported the full clip as a sequence of stills, opened in QuickTime and then exported as a movie. This solved the level mismatch, but is cumbersome.


Lee Berger
http://www.leebergermedia.com


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peter mcauleyRe: Levels change when using Witness Protection
by on Jun 21, 2007 at 3:56:05 pm

Hi Lee,

By effect method I meant were you using the blur, the mosaic, the brightness, or the tint. The default effect is a blur.

I'll check with engineering to see if someone knows why we would clip levels like that and I totally understand how this would be a problem in the workflow that you are using.

Thanks for reporting this.

Cheers,

Peter.



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mark harveyRe: Levels change when using Witness Protection
by on Jun 22, 2007 at 10:34:54 am

In prefs there used to be a setting that was called generate color safe levels....Is that preference activated in your Borisfx preferences ????

Mark


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Lee BergerRe: Levels change when using Witness Protection
by on Jun 22, 2007 at 7:56:06 pm

Thanks Mark,
That's an interesting thought, but Boris Continuum (BCC) for Final Cut Pro is a plugin with controls native to the FCP interface. In other words the familiar Boris FX or Red Keyframer does not open when you apply a BCC filter in FCP. All settings and keyframes are done in the Filters tab of the Viewer Window. Aside from Help and Open/Save Presets, there is no preferences setting. It seems that if you want safe colors you have to add a BCC filter called (what else) "safe colors."

Perhaps the color safe setting is hard coded into the plugin?



Lee Berger
http://www.leebergermedia.com


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peter mcauleyRe: Levels change when using Witness Protection
by on Jun 25, 2007 at 3:34:15 pm

Hi Lee,

I discussed this problem with engineering and they told me that what you are seeing may be due to the conversion from YUV to RGB and then back. BCC filters process color internally in the RGB color space.

If you could please send me a zipped sample frame, before and after, we'll take a look at it in our labs to see if there is anything that might be done to prevent this from happening. My email is peterm@borisfx.com

Cheers,

Peter.



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Lee BergerLevel Change Work Around
by on Jun 28, 2007 at 2:25:14 pm

For those interested, a work around is to apply a BCC Safe Colors filter (under BCC 4 Color Blurs) to the incoming clip which will match the levels and is a relatively quick render. In the meantime Boris engineering is looking into the problem. Thanks to Peter for his assistance.

Lee Berger
http://www.leebergermedia.com


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