cmyk color encoding model in DR?

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dariusii

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cmyk color encoding model in DR?

PostTue May 11, 2021 4:10 pm

Hi all.
Hadn't see any topic about cmyk color space in Davinci.
There are a lab one, but not cmyk.
I understand, that cmyk are used for print and not for any viewports, but with cmyk curves very comfortable to correct color. There is a black point compensation strategy. I can change contrast of saturation for every cmy channel. Values of cmy curves stand not at lignthness, but on vibrance/color boost (resolve). As in ab (lab) curves. But lab paradigm is more harder, than rgb/cmyk.

But if developers hadn't that one, that they were thinking about something.

An example, how can use cmyk curves:
Last edited by dariusii on Sun Nov 21, 2021 8:42 pm, edited 1 time in total.
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Re: cmyk color space in DR?

PostWed May 12, 2021 7:07 am

It's very strange, that the topic no one's interested.
Excuse me, that I'd begin it.
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Re: cmyk color space in DR?

PostWed May 12, 2021 8:35 am

You can use RGB + luminance in most of the color controls which is in essence the same as CMYK. Also any true CMYK color profile would have a gamut that was partly outside any RGB output space which would be problematic.
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Re: cmyk color space in DR?

PostWed May 12, 2021 9:51 am

CMYK is a PRINT color profile and not for digital video

https://en.wikipedia.org/wiki/CMYK_color_model

Flyeralarm_CMYKvsRGB_en.png
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Re: cmyk color space in DR?

PostWed May 12, 2021 9:59 am

rgb+luminance is based on luminance curve. 0-255/black-white. a color value is based on luminance curve. cmyk based on saturation curve. 0-255/high vibrance-low vibrance. as in lab.

cmy isn't a just "inverted" rgb (red-cyan, green-magenta, blue-yellow).
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Re: cmyk color space in DR?

PostWed May 12, 2021 10:03 am

Mark Foster wrote:CMYK is a PRINT color profile and not for digital video


dariusii wrote:I understand, that cmyk are used for print and not for any viewports, but with cmyk curves very comfortable to correct color.


pseudo cmyk as in 3dlc.
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Re: cmyk color space in DR?

PostWed May 12, 2021 10:08 am

Just I can't use lab color space for curves, because curves in Davinci resolve have a s-shaped curve. I can't use broken line in resolve's curve. For lab curves it's better, than s-shaped as for rgb.

A right example of lab curves - Canopus Edius' lab curves. There's I can use broken lines for that curves. As and into 3dlc app.
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Re: cmyk color space in DR?

PostWed May 12, 2021 6:24 pm

2 Mark Foster

I won't gonna to render video in cmyk image stills))

..strange people.
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Re: cmyk color space in DR?

PostWed May 12, 2021 6:55 pm

Mark Foster wrote:CMYK is a PRINT color profile and not for digital video

Oh no! Will monitor start oozing ink? In all seriousness this is absolutely irrelevant what the primary use case is for some color system, can you tell me if component value 0.27 is from RGB or CMYK system?
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Re: cmyk color space in DR?

PostWed May 12, 2021 7:51 pm

Perhaps, people say about color gamut. In rgb one the gamut wider, than in cmyk, but what prevent to wide it. Artifically.
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Re: cmyk color space in DR?

PostThu May 13, 2021 5:53 am

cmy curves = sat vs sat curve (Davinci), but for separate c, m and y channel.
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Re: cmyk color space in DR?

PostSat May 29, 2021 11:29 am

So does somebody know, how to create node' structure, that be emulate cmyk curves? ;(
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Re: cmyk color space in DR?

PostFri Nov 19, 2021 7:21 pm

bump
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Re: cmyk color space in DR?

PostFri Nov 19, 2021 8:32 pm

Read through this. https://hg2dc.com/

If you have questions, Troy responds on Twitter.
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Re: cmyk color encoding model in DR?

PostFri Dec 03, 2021 11:02 am

It seems that everyone are indifferent to this topic.
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Re: cmyk color encoding model in DR?

PostFri Dec 03, 2021 12:02 pm

It's interesting but for Resolve there are already countless ways to work an image for good skintones or looks in general. I don't think an added CMYK model is that necessary. The fairly recent addition of the color warpers gives us plenty flexibility.
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Re: cmyk color encoding model in DR?

PostSun Dec 12, 2021 7:37 am

shebbe wrote:It's interesting but for Resolve there are already countless ways to work an image for good skintones or looks in general. I don't think an added CMYK model is that necessary. The fairly recent addition of the color warpers gives us plenty flexibility.


Somebody told me (about 3 years ago), these things (color warper etc) are not needed ;) About grids from 3D LUT Creator, that brazenly took from Oleg Sharonov. Why? what's the point...
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Re: cmyk color encoding model in DR?

PostSun Dec 12, 2021 12:38 pm

RGBW
In "1" node, in gain, we disable luma only.
Node "2" we can change luma.
In nodes r, g and b we can to change saturation for every rgb channel - with curves etc.. As for cmy in cmyk. left side of curve is max white generation point. The right side is max gen of saturation for channel.
In every r, g and b node we are turning off colors to 0 in rgb mixer. For red node we disable to 0 green and blue levels etc.

Now, we can make a cmyk converting - rgb mixer.

/upd
we can use a combiner node instead parallel one.
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