Debayer knowledge

[simonphw]

Hello all

This is my first posting so forgive me if I'm asking the obvious and its also in the right place.
I have just finished an edit for a friend on Final Cut pro, who shot it on a red camera.
I have a little bit of experience with FCP and Red but I'm no expert.
The footage i had to work with had been trans-coded from the 2K RD3 files by someone else to Apple pro res and they looked good.
The project all worked fine until I came to outputting it for the grade.
The graders had asked me to send them a Tiff sequence so i reconnected the footage back to the F Red proxies so i could create it, I had done this a couple of times before and it worked fine.
I noticed that the proxy files looked like they had a blue tinge to them.I had not seen this before in the couple of times i had reconnected on other projects.
I now know that I should of called the graders at this point to see if this was right.
When the people doing the grade saw them they starting talking about "debayering" and had problems getting the Tiff into there system, I don't know what they are using to grade.
I have looked online at this and frankly am left a bit confused.
In the end they asked me to make an EDL of the cut and they made a DPX file and graded from that.
I would like to know more about this to avoid this problem in the future.
If this all makes sense or i have not put enough information then i will add.
Any help advice or knowledge on this would be fantastic and much appreciated.

Thanks

Simon

 

[I Bloom]

Simon,

Debayering is the process of turning an image from what we call Bayer Raw to RGB. Which basically means converting it from the raw pattern recorded on the sensor to a complete image with red, green and blue components for each pixel.
http://en.wikipedia.org/wiki/Bayer_filter

There are actually many different algorithms for going from Bayer to RGB, some are faster and some are much higher quality, but need alot of computational power to do thousands of frames of 4K. I'd need to check with the latest from Red, but from what I know, none of the quicktime reference files do a full debayer of your image. Especially when working with 2K original material, you may find this is really important. Likewise, compression and loss of bit depth can also occur in that pipeline.

I'm not sure if that has anything to do with a blue tint. You may want to consider using a grader with more experience with Red, such as Offhollywood, LocalHero, LightIron, or PlasterCity.

IBloom

 

[Simon Blackledge]

The blue tint is the QT proxy issue with pre 20 material being pushed through the new colour science.

you can re white balence the r3d's in redalert but the proxies wont act the same.

try updating to the latest Quicktime codec from Red.com 3.9 i think. apparently it solves the proxy issue though I have not had time to upgrade yet.

RedTeam, is this proxy new colour science fixed yet?

Cheers

Si


s

 

[simonphw]

hello bloom and fellow Simon

Thanks for all of this information.
I understand it a bit more now and will do some tests.

Thanks again

Simon

 

[Jeff Kilgroe]

Simon,

If you are creating TIFF or DPX sequences for color grading and finishing, you do not want to generate from the proxies. Better to create them from other tools like red alert w/ redrushes, clipfinder, etc.. The proxies often have gamma and color space issues, you can't change your color space or color LUT / curve / look or whatnot. You don't have control over them.

 

[jimhare]

Jeff and Ian are right, it's easy to make a mess if this isn't done right.

In my opinion, this is what has caused some negative views when it comes to RED's quality. The post gets massacred and RED gets blamed.

In my opinion, your best bet would be to use a grading suite that first has RED experience, and second uses a system that can talk to RED R3D files directly, such as SCRATCH or even COLOR.

I don't think they would be asking you to export TIFFs if this were the case.