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RGB target values for DaVinci Resolve

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Arturo Sinclair
RGB target values for DaVinci Resolve
on Sep 1, 2014 at 8:16:43 pm

Hi all, does anyone know what the RGB values are for the target values on the vectorscope? In other words for R, Mg, B, Cy, G and Y. I am trying to create a color card (hard copy) that I can use and that has those primary and secondary color values to use as a reference during shooting. (please don't suggest I buy a CamAlign or similar for a few thousand dollars!)

Any help will be very much appreciated,

Arturo


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Bill Ravens
Re: RGB target values for DaVinci Resolve
on Sep 1, 2014 at 10:53:53 pm
Last Edited By Bill Ravens on Sep 1, 2014 at 10:55:51 pm

The answer to your question may not be too simple. Target values for HD content is defined as 100%. You'd have to refer to a CIE Color Chart to relate the XYZ values to the targets. According to the REC709 specification,
xW= yW= xR = yR= xG= yG= xB= yB=
0.3127 0.3290 0.64 0.33 0.30 0.60 0.15 0.06



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Arturo Sinclair
Re: RGB target values for DaVinci Resolve
on Sep 2, 2014 at 2:45:49 pm

Thank you for your suggestion, very helpful. I did find a calibrated CIE color chart with all values printed as well from http://www.brucelindbloom.com/ if anybody else is interested. More technical explanations as to how to interpret and apply these values (including a script) are at http://www.rags-int-inc.com/PhotoTechStuff/AcrCalibration/.


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Peter Chamberlain
Re: GB target values for DaVinci Resolve
on Sep 2, 2014 at 1:38:24 am

I don't suggest you try to make your own chart. The one shot and spyder and x-rite pocket are us$100 or less and have known xyz values under the d65 illuminate.


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Arturo Sinclair
Re: GB target values for DaVinci Resolve
on Sep 2, 2014 at 2:53:18 pm

Thank you for your response. The cards you mention are very good for small product shots etc. but I need a larger card. Also I need the digital file of the card to use in DaVinci to demonstrate certain functions and it is practically impossible to get accurate values by either photographing or scanning the card (specially if the are protected, like DSC's CamAlign.
Now that I have all individual values, primaries, secondary and additional (like skin tones) etc. I'll have an accurate digital file that I can use as a reference to the one shot on location,


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Bill Ravens
Re: GB target values for DaVinci Resolve
on Sep 2, 2014 at 6:53:00 pm

Peter is right. There's a reason the Cam-Align charts are so expensive. It's very hard to find pigments that will reflect the appropriate frequency. To complicate the issue, most pigments are transient. That is to say, fading begins to occur almost immediately, so, even if the reflect the right frequencies to start with, they won't for long. Making your own targets are, well, not an easy proposition.



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Marc Wielage
Re: GB target values for DaVinci Resolve
on Sep 3, 2014 at 4:22:13 am

I had a 15 minute with David Corley of DSC Labs some years back, and I got an earful as to just how difficult it is to make camera alignment charts that come back with the color vectors right in the boxes.

To me, I think you're just as well off shooting a grayscale chart, showing what we used to call DMin and DMax in scanning (blackest black and whitest white), make everything else neutral, then look at the scene and adjust to taste. No automatic control or magic camera chart can do better than that.

What complicates the process is many cameras tend to hype certain colors more than others, so getting linear results is problematic.


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Margus Voll
Re: GB target values for DaVinci Resolve
on Sep 3, 2014 at 10:12:55 am

As Marc said no auto tool can fix camera footage when some serious woodoo has been applied
to the footage in your camera body before recording.

Peter has pointed at that also in some other thread or forum.

I feel that Marc's way of balancing "ligth" and adjust colour to taste is rather fast if you are experienced
with scopes.

--

Margus

http://iconstudios.eu
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