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Juan Juig
Importing 601/709 footage
on Oct 10, 2015 at 5:47:49 pm

Hello,

I understand what happens with RGB footage once imported (with either RGB or 601/709 settings) into Avid, but what I do not know is, what happens with footage that was shot in 601/709 colour space.

I would like to know, what happens to the footage if you choose RGB import under import settings or 601 for SD 709 for HD option.

Also I wonder what then happens with footage once you export it as RGB or 601/709. How does an RGB monitor displays colours and how 601/709 displays colours with different exports.

Cheers

Juan


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Michael Phillips
Re: Importing 601/709 footage
on Oct 10, 2015 at 6:43:15 pm

Getting all the nuances and differences between color spaces can be quite as task. Here is a primer on Color FAQ by Charles Poynton for starters:

http://www.poynton.com/PDFs/ColorFAQ.pdf

Or get the second edition of his book - Digital Video and HD, Second Edition: Algorithms and Interfaces:
http://www.amazon.com/gp/product/0123919266?keywords=charles%20poynton&qid=...

Or this one:

http://www.amazon.com/gp/product/047112253X?keywords=charles%20poynton&qid=...

Or visit his site or subscribe to some of his seminar/webinars:

http://www.poynton.com/


That being said - Avid's import/export setting affect levels more than anything else that might be visible to the eye to the average user. If video is 601/709 and you choose RGB, you are telling Avid to scale black and white levels as though they were 0-255 (8 bit terms). So if you had black at 16 and 235 and chose RGB, 16 would become closer to 30 and whites would be closer to 200. You can do a very simple test yourself and make 4 squares in Photoshop that are in RGB terms:

0, 0, 0
16, 16, 16
235, 235, 235
255, 255, 255

And import with both settings and use the color dropper to see what the values are once imported. If you select 601/709, then your levels remain the same. Video is also YCbCr and you can read up on that as an overview here:
https://en.wikipedia.org/wiki/YCbCr

As mentioned elsewhere, color space conversion will happen with some rounding, but difficult to see to the normal eye - the biggest difference in Avid misleading import terminology will be the black and white levels of the image. In v7 and later, you can bring everything in "full range" and work with LUTs if desired.

As far as monitors go, reading up on monitors like the Dreamcolor will give you an idea of what those differences are and the use of different color gamuts.

https://library.creativecow.net/articles/garchow_jeremy/HP_DreamColor_CRT_R...



Michael


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