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Difficult to fine tune colors in Resolve

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Itai Bachar
Difficult to fine tune colors in Resolve
on Nov 26, 2013 at 1:02:22 pm
Last Edited By Itai Bachar on Nov 26, 2013 at 1:14:11 pm

Hi all
Sorry for the dramatic title,
but I find it is extremely difficult to work when,
at 0.001 green gain (for example) the shot looks too green,
and at -.001 it looks magenta.
I mean, there is not enough space to work within, the tolerances are too tight, theres a microscopic range that I can use.
Luminance seems to have plenty of range,
and it doesnt react so extreme.
(currently working on Alexa log-C Pro-res materials)
Any tips?
Thanks
Itai


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Toby Tomkins
Re: Difficult to fine tune colors in Resolve
on Nov 26, 2013 at 1:44:14 pm

Sounds like you could be a Tetrachromat!

But to answer your question, use a node's output gain to fade the adjustment node effect from 0-100%


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Juan Salvo
Re: Difficult to fine tune colors in Resolve
on Nov 26, 2013 at 1:52:47 pm

Can you describe a bit more about how you are working? Are you adjusting under a lut, in aces? Do you have a node that's increasing your saturation perhaps? How are you monitoring?

http://JuanSalvo.com
http://theColourSpace.com


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Itai Bachar
Re: Difficult to fine tune colors in Resolve
on Nov 26, 2013 at 2:24:01 pm

Im "LUTing" it manually, just adjusting some primaries and curves,
nothing out of the ordinary, monitoring on a calibrated apple cinema.
I'm attaching a screenshot, showing the greenish cast achieved by 0.01 gamma change. it is really a struggle currently to fine tune this.
(I am new to resolve)
Thanks



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Kevin Cannon
Re: Difficult to fine tune colors in Resolve
on Nov 26, 2013 at 3:38:35 pm

Hi Itai, could you show your node tree and give your order of operations?

Keep in mind that if you put the LUT (or corrections that do the same) in a later node (say node 3), that will drastically exaggerate changes you make in nodes 1 and 2. But if you add a node 4 the corrections you make there won't be multiplied by the LUT, so to speak. For that reason I like to set up three node: 1 is for rough adjustments to the log image, 2 is for the LUT (or corrections that do the same) and 3 is for fine adjustments.


KC

Prehistoric Digital


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Itai Bachar
Re: Difficult to fine tune colors in Resolve
on Nov 26, 2013 at 7:39:33 pm

Hi Kevin, my node tree is actually similar to what you are describing,
I do the LUT (either Arri lut from the 3d lut menu, or my own "lut"),
than minor tweaks.
So I guess no un-necessary "multiplications" happening,
have I got it right?
Thanks


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Marc Wielage
Re: Difficult to fine tune colors in Resolve
on Nov 26, 2013 at 11:39:33 pm

[Itai Bachar] "Hi Kevin, my node tree is actually similar to what you are describing, I do the LUT (either Arri lut from the 3d lut menu, or my own "lut"), than minor tweaks."
What happens if you eliminate the LUT entirely and just use the first node to simulate the actions of the LUT? I have encountered Log-C situations before where I just went at it with no LUT and did just fine.

Bear in mind that in The Old Days, we color-corrected for decades without LUTs using film, which is always photographed Raw, essentially in Log space. It can be done, it's just a question of where you need to go and what you're trying to do.

BTW, I always find it's best to use the first node to get the image to something approaching normal, then do all the fine-tuning downstream from there. Whether I use the LUT or not is dictated by the material.


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Itai Bachar
Re: Difficult to fine tune colors in Resolve
on Nov 27, 2013 at 9:52:13 am

I actually work like that. I check the Arri LUT, sometimes it gives me a good result, but many times it
looks wrong, too contrasty, colors become to blue and other oddities.
On this job, I have a few clips that took the Arri LUT nicely, and many others that I correct myself.
As you say, first node is for primary and overall level and than more tweaks.
I worked like that in a few cases before and noticed Resolve's, or my system config + Resolve, "lack of color space" behavior, and I actually thought this is because I don't have a Panel,
but this project is too much, this is close to unusable.
Maybe it's the version 10 beta?
But again, I did 2 jobs before this and it behaved flawlessly.


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Joseph Owens
Re: Difficult to fine tune colors in Resolve
on Nov 26, 2013 at 4:58:45 pm
Last Edited By Joseph Owens on Nov 26, 2013 at 5:02:58 pm

[Itai Bachar] "nothing out of the ordinary, monitoring on a calibrated apple cinema."

For starters, you're more than likely monitoring in 8-bit, so what you think is a .001 change is quite a bit more than that even if you are working in full scale 0-255, less if you're working in 709. Hues are going to pop in large increments, more than one degree at a time, if you do the math. (360/255, roughly, at full saturation.)

If not for any other reason, the coarseness of an 8-bit display, which describes most graphics monitors, disqualifies them for grading. Apple Cinema Displays are particularly bad, "calibrated" or not.

As far as tetrachromatic color vision goes, I thought that was genetically impossible for males, my understanding being that the trait resides on the second X-chromosome. But that reflects an imperfect understanding on my part, probably.

jPo

"I always pass on free advice -- its never of any use to me" Oscar Wilde.


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Itai Bachar
Re: Difficult to fine tune colors in Resolve
on Nov 26, 2013 at 7:52:08 pm
Last Edited By Itai Bachar on Nov 26, 2013 at 7:53:40 pm

Hey Joseph
Thanks for the scientific explanation, I guess I'll need a pro grade monitor one of these days.
In what way apple monitors are worse?
Can you recommend a monitor (a computer monitor) that will be better for the job than apple cinema, or they are all un-qualified?
What about those Eizos and NEC pa's, or any other high end pc monitor?
Or is that will always be a compromise and I need a pro broadcast monitor?
those work in 10 bit?
Thanks

Tetrachromatic? you guys can see the green cast in the screenshot above,
no need for special female genes... just plain eyesight...
:-)


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Toby Tomkins
Re: Difficult to fine tune colors in Resolve
on Nov 26, 2013 at 8:11:14 pm

That is an oddly large change, 8 bit or not! The gene has only been discovered in women but I don't think there's a limit on the genetics side to women but I might be wrong, it was just a throwaway comment as a joke! (-;

I think something is wrong with your install or set up. Try reinstalling the latest version maybe? If you do t want to do that then use my workaround described in the first reply I gave! This will also test the 8 bit monitor issue but I highly doubt this is the case.


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Itai Bachar
Re: Difficult to fine tune colors in Resolve
on Nov 26, 2013 at 9:03:59 pm

Yes I agree this is odd, though I did encounter this "narrow color space"
before in Resolve, but I have just a few projects under my belt with it.
Your workaround is useful, and your joke is useful too! :-)
thanks


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Juan Salvo
Re: Difficult to fine tune colors in Resolve
on Nov 27, 2013 at 4:43:16 am
Last Edited By Juan Salvo on Nov 27, 2013 at 4:45:31 am

Itai, can you post a drp of your project. I'm curious to solve this one. :)

Also a screen grab of your system preferences>display>color page. Have you tried to "calibrate" the apple Cinema Display... Maybe with something like a spyder colorimeter?

http://JuanSalvo.com
http://theColourSpace.com


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Itai Bachar
Re: Difficult to fine tune colors in Resolve
on Nov 27, 2013 at 9:12:37 am

Hey Juan
The monitor is calibrated with an X Rite i1.
But even if it wasn't calibrated, Resolve would still behave like that.
Im uploading and sending you the drp,
I cant see what prefs page you want me to grab, It sounds like a mac...
I'm on a win 7 box, running Resolve Lite 10b, gtx680 card.
Thanks


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Adam Claude Jones
Re: Difficult to fine tune colors in Resolve
on Nov 27, 2013 at 10:23:35 am

[Itai Bachar] "What about those Eizos and NEC pa's, or any other high end pc monitor?"

I'm thinking of getting an Eizo CX240 or CS230. They can do 10 bit if you use Display port. But you would need a Blackmagic card to send out a correct video signal. I was told that a set up using these monitors and Resolve's Monitor output LUT for 3D LUT calibration is a valid workflow.


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Joseph Owens
Re: Difficult to fine tune colors in Resolve
on Nov 27, 2013 at 11:28:09 pm

[Itai Bachar] "In what way apple monitors are worse?"

One part of my reservations about Apple generally is that they have consistently shown a fairly limited understanding of SMPTE/EBU CCIR practices. They cannot decide what gamma to use for display transfer functions and this has lead to an almost universal mistrust of exported media. Depending on decoders, displays, and operating systems, you *might*, but usually *might not* get back what you thought you were sending out. Beyond that, at least the Apple Cinema Displays are *not* designed to tell the truth -- they are juiced to make everything look "great"... and they are all glossy now, you can't get the matte low-glare glass anymore. Its actually harder to find something 'right' with them than it is to list everything that is wrong with them, which is just about everything. The power supplies fail regularly, and it is pretty much impossible to fix or replace them... shall I go on?

As far as the green/magenta flip/flop, its another argument against using mouse/stylus controls as a User Interface. Even back when we were exclusively grading in SD, daVinci systems were famous for over-sampling, not just at 4:4:4, but at 8:8:8 (which resulted in the name of their intermediate SD grade system). The current spec for Resolve is to process the source data in 32-bit float, which should have a very high degree of fine-ness.

It sort of reminds me of an incident that occurred while there was a pan-and-scan job in the telecine gate a number of years ago. A trainee was assisting, and noted that my X-Y coordinates were "not exactly" half of the maximum/minimum excursion values for a centred image. One issue with that is that the 8:8:8 displayed all its parameters in hexadecimal... so math in base-16 is not the same as base-10, that's just one issue, but the other reality is that interlaced 525i29.97 doesn't really have a 0/0 center value -- in the world of 262.5 interlaced lines, 240 of which are active in any particular field, there will always be a slight geometric offset, but nothing below .5% is gong to make any difference at all because we are dealing, once again, with a sampled system. That means something else in the greater field of Communication Theory. So the reality was that there was no "line" that would be exactly centred vertically... its an even number of lines, so half would have to be above a certain point, and the other half would need to be below that value. Its a little like the joke that half of the people you might meet are "below average."

You might note that you can really only adjust blur/mist in Resolve in 2-pixel increments (that has an effect), and certainly only even-number amounts are actually saved and retrieved. You mibght get the feeling that what we do is an inexact science...

jPo

"I always pass on free advice -- its never of any use to me" Oscar Wilde.


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Juan Salvo
Re: Difficult to fine tune colors in Resolve
on Nov 27, 2013 at 4:41:15 am

jPo, you're right as usually. Technically the marker which would support the development of a third type of color receptor, and tetrachromatisis, would only be found in a second X chromosome.

http://JuanSalvo.com
http://theColourSpace.com


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Fred Ricci
Re: Difficult to fine tune colors in Resolve
on Nov 27, 2013 at 9:07:11 am

Are you using a panel?
Tweaking values with numeric pad or mouse gives you this "odd jumps".
When working with a panel, you get much more range than whats showing in the gui.

Resolve Beta 10 OSX 10.8.2
Macpro 5.1 12x2,66
GTX 570 MacVidcards
12 Giga RAM
16 Giga SAS


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Itai Bachar
Re: Difficult to fine tune colors in Resolve
on Nov 27, 2013 at 9:19:55 am

No, a wacom stylus.
I can take this to a post house that has a panel, to check this out,
thanks


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Andy Winter
Re: Difficult to fine tune colors in Resolve
on Nov 28, 2013 at 8:09:10 pm

perhaps i dont get it, but:
isnt the picture still greenish after the correction?

and: even with the mouse you are able to finetune much subtler changes,
only the displayed numbers change "later".


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Juan Salvo
Re: Difficult to fine tune colors in Resolve
on Nov 29, 2013 at 12:29:49 am
Last Edited By Juan Salvo on Nov 29, 2013 at 3:14:53 am

Itai actually sent me his project. I found the same. Adjusting with the mouse while looking at the digits indicator resulted in steppy adjustments, but there was actually much finer graduation available.

One technique I suggested to him, was to have one node where he doubled the saturation to 100 then another node where he would make his adjustments, then a third node where he would half the saturation to 25. This gives the second node a much finer level of operation in terms of color balance.

That said, this is a non-issue if one doesn't look at the numbers, or if one uses the panel interface instead and again, doesn't look at the numbers.

http://JuanSalvo.com
http://theColourSpace.com


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Robert Ruffo
Re: Difficult to fine tune colors in Resolve
on Dec 6, 2013 at 11:07:58 pm

True 8 Bit is fine, the problem is an Apple cinema is less than 8 bit and does not display all colors in the 8 bit palette.

Another problem is if you are using a LUT to correct your apple display, in 8 bit, there is your multiplier right there.


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