[Tig] RGB to XYZ on Resolve

Rogério Moraes rogermamo at gmail.com
Thu Feb 16 12:29:54 GMT 2012


Yes! That´s some o f my problme plus I get darker images. Wich, for m, goes
up to the question : in the RGB>XYZexporting the Resolve applies a 2.6
gamma or preserves the native RGB gamma form the unrendered material, the
one in the timeline (let´s say REC 709, a log-to-lin with a baked in LUT).
the color conversion is pure martrix mathematics, and the numbers can be a
little off in one or another software, thus the resulting greenish tone.
But what about the Gamma? I use easyDCP and if I do bypass the color
convertion I (and thye software) are assuming that the image is already DCI
compliant in terms of color sapce (XYZ, and gamma). XYZ, easy to spot the
difference, but what about gamma? Who can say for sure that the input image
is already with the required gamma? All coments are welcome at this stage.
Thanks all

Yes! That´s some o f my problme plus I get darker images. Wich for me goes
up toi the alley os the question : in the RGB correction the Resolve
applies a 2,6 gamma or preserves the native RGB gamma form the unrendered
material (let´s say REC 709, a log-to-lin Lut). the cocolor conversion is
pure Martrix mathematics, and the numbers can be a little off in one or
another software, thus the resulting greenish tone. But what abou the
Gamma? I use easyDCP and if I do bypáss the color convertion I (and thye
software) are assuming that the image is already DCI compliand in terms of
color sapce (XYZ, and gamma). SXY, easy to spot the difference, but what
about gamma? All coments are welcome at this stage.
Thanks all

---------- Mensagem encaminhada ----------
De: "Susiluoto Jarni" <Jarni.Susiluoto at kava.fi>
Data: 16/02/2012 07:35
Assunto: VS: [Tig] RGB to XYZ on Resolve
Para: "Rogério Moraes" <rogermamo at gmail.com>

Hello

I've tried to use Resolve's own rgb2xyz LUT and render out both 10bit DPX
and 16bit XYZ tiff. DCP were made with Curator and bypassing color
conversion.  BW originals appeared to get greenish tone in projection...

Have anyone any idea for what that Resolve's LUT is supposed to use for?

Jarni Susiluoto

Film Technician
National Audiovisual Archive, Finland

-----Alkuperäinen viesti-----
Lähettäjä: tig-bounces at colorist.org [mailto:tig-bounces at colorist.org]
Puolesta Rogério Moraes
Lähetetty: 15. helmikuuta 2012 18:33
Vastaanottaja: gold at duplicorp.com
Kopio: TIG
Aihe: Re: [Tig] RGB to XYZ on Resolve

Sohonet http://www.sohonet.co.uk sponsors the TIG.
Support from Nucoda www.imagesystems.tv
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No responses yet. It appears that the 8.2 Resolve deals with some DCI/XYZ
issues( found a thread here http://www.knuterikevensen.com/?p=711 ). Since
I do not have this version, and at 8.1 Resolve does not output .j2c files
(basically, I'm trying to improve a DCP workflow) the gamma (or degamma)
question still is the main point for me in here. Where in Resolve should I
tell it to output the image (even if a tiff... my  DCP software will do the
.j2c/mxf wrapping, without color converting to XYZ and the required gamma
later, if the image is already DCI compliant) with a 2.6 gamma? Will I have
to create a 3d LUT for this?
Thank you all

2012/2/15 gold at duplicorp.com <gold at duplicorp.com>

> Hi Rogério,
> I didn´t find  a response to your question and I am very intersted in it.
> Did you receive a response or found anything new?
> Thank you in advance for any info you can give me.
> Daniel Goldschlager
>
> DRG New Media
> Caracas, Venezuela
>
> Original Message:
> -----------------
> From: Rogério Moraes rogermamo at gmail.com
> Date: Mon, 13 Feb 2012 12:15:18 -0200
> To: tig at colorist.org
> Subject: [Tig] RGB to XYZ on Resolve
>
>
> Sohonet http://www.sohonet.co.uk sponsors the TIG.
> Support from Nucoda www.imagesystems.tv Support from Blackmagic Design
> http://www.blackmagic-design.com/ Have a beer in Hollywood on 9 Feb.
> Details:
> http://tig.colorist.org/pipermail/tig/2012-January/019841.html
> ====
>
> Hello
>
>      In an experiment, I was trying to do a color conversion from a
> REC
> 709 colorspace to an XYZ, for DCI compliant images on a Resolve and as a "
> control group", did the same on AE. Got two different images as output....
> my question: does anyone knows what kind of conversion Davinci Resolve
> does when exporting (rendering) a REC 709 graded material (or in any
> RGB color
> space) to an XYZ .tiff? Does it apply a gamma of 2.6 for the XYZ color
> space or just converts the color gamut matrix for it's calculations,
> resulting in an XYZ colored image, but with a different gamma (2.2 is
> my guess)?
> Thanks for the attention
> --
> Rogério Moraes
> _______________________________________________
> http://reels.colorist.org
> http://tig.colorist.org/wiki3
>
>
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--
Rogério Moraes
_______________________________________________
http://reels.colorist.org
http://tig.colorist.org/wiki3


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