Blackmagic Forum

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.

It's very strange, that the topic no one's interested.
Excuse me, that I'd begin it.

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.

CMYK is a PRINT color profile and not for digital video

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

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).

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.

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.

2 Mark Foster

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

..strange people.

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?

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

cmy curves = sat vs sat curve (Davinci), but for separate c, m and y channel.

So does somebody know, how to create node' structure, that be emulate cmyk curves? ;(

bump

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

If you have questions, Troy responds on Twitter.

It seems that everyone are indifferent to this topic.

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.

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...

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.

Hello, I really need this node for converting to CMYK. I did not make it myself as you described. Can you share a powergrade with me? Thank you so much. This is especially useful for me. I also prefer CMYK curves for colour mixing.

dariusii wrote: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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