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ProRes Auto Gamma On or Off?

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James Vincent
ProRes Auto Gamma On or Off?
on Mar 11, 2013 at 8:08:57 pm

TV show is being shot on sony XDCAM HD Discs at:

1080p 23.98 Compression XDCAM HD 422

The Files will be brought in then transcoded to Apple ProRes 422 for online and Apple ProRes 422 Proxy for offline editing.

My question is the gamma correction tab in compressor (under video). The options are Automatic or None.

Which one is correct to use for broadcast?

One thing I do know is that the automatic setting takes twice as long to compress out then having none selected.

Thanks

james

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40tb Xsan


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James Vincent
Re: ProRes Auto Gamma On or Off?
on Mar 11, 2013 at 8:28:36 pm

Just looking at the clips in fcp with the scopes up and my broadcast monitor on I can't tell any difference just a note

Heres what it says about gamma correction directly from apple

Apple ProRes Tips

This section lists some practical tips for working with Apple ProRes codecs.
Gamma Correction

Apple ProRes codecs have a native gamma of 2.2. The Gamma Correction setting in the advanced compression settings pane allows you to disable the automatic 1.8 to 2.2 gamma adjustment that can occur if RGB material at 2.2 gamma is misinterpreted as 1.8. In some cases this gamma adjustment is not desirable (for example, if the source image is RGB 2.2, or if the encoded Apple ProRes file is meant to be used in another RGB-based application).

Automatic: Select the Automatic setting to have the Apple ProRes codec convert RGB 1.8 gamma source media files to 2.2 gamma.
None: Select the None setting to disable the adjustment of 1.8 gamma to 2.2 gamma.


So is the better question to ask is the pdw-700 camera recording at 1080p23.98 50mb @ XDCAM HD 422 , is it already a 2.2 gamma or does it record in a 1.8 gamma?

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David Kuhnen
Re: ProRes Auto Gamma On or Off?
on Mar 13, 2013 at 7:01:32 pm

Typical setting is to leave on Automatic.

That being said, a professional video camera will record files in a YUV color space (as opposed to images created in a RGB color space) and will not need gamma correction when converting to Apple Pro Res. so, for conversion of your XDCam files, you can select None.

David Kuhnen
BVK-Milwaukee
Video Editor/Engineer


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