CMYK channel mixer problems..

[saberlancer]

Hi,can anyone help? Thks thks.
I usually convert to B/W for RGB using channel mixer, which works great.

But when I work in cmyk, using channel mixer to convert seems to give it a very 'washed out' look. My image must remain in CMYK mode but grayscale.

[mistermonday]

Saberlancer, why don't you just bring the image into RGB or LAB first. Use one of the 10 methods to convert to grayscale and when you are done convert the image back to CMYK?
Regards, Murray

[saberlancer]

Thks Murray,
Well thats one alternative I've been using..
Just wondering if there's a way to retain the channel mixer layer and just show/hide.

Any reason why it works so much better in RGB than CMYK?
I mean the channel mixer method to adjust/convert to B/w.

[Kraellin]

saberlancer,

i'm no coder, but color mixer seems to have been made pretty much for rgb mode. i mean, even the sliders are labeled red, green and blue.

why not use hue/saturation? you can simply move the saturation slider all the way to the bottom. this removes all the color but keeps you in 8 bit color mode.

[saberlancer]

Originally Posted by Kraellin

saberlancer,

i'm no coder, but color mixer seems to have been made pretty much for rgb mode. i mean, even the sliders are labeled red, green and blue.

why not use hue/saturation? you can simply move the saturation slider all the way to the bottom. this removes all the color but keeps you in 8 bit color mode.

Hi Kraellin, actually the channel mixer in cmyk files are CMY&K.
Another question is that when I use saturation to 0%,my file appear 'reddish'..why?

Again this is only for CMYK, RGB is fine..

Help...

[OnAir]

In CMYK mode you are working with channels, that are build according to a certain printing process. Structure of every channel is very much depends on CMYK profile. Sometimes it is impossible to build nice structure, only mixing channels. Go with Lab, it is better.

[saberlancer]

Originally Posted by OnAir

In CMYK mode you are working with channels, that are build according to a certain printing process. Structure of every channel is very much depends on CMYK profile. Sometimes it is impossible to build nice structure, only mixing channels. Go with Lab, it is better.

I've considered LAB.
But my stuff go to print CMYK. So if I work in LAB, then convert to CMYK,there'll be color shift right?

Does any DI/retouchers here use LAB?How to control color shifts issues?

[OnAir]

When speaking about grayscale conversion via Lab, I meant, that you need to convert your image to Lab, then desaturate, usually add some contrast and after convert to grayscale or CMYK with your printing profile.

[Ant]

For B&W, it is standard practice to use Quadtone.

[KR1156]

what colors do you normally set for your quadtones?

maybe it varys for the feel your going for, cool, warm etc.?

or do you mean you get the tonal values that you like using quadtne colors, then convert to grayscale?

[CJ Swartz]

Originally Posted by saberlancer

Thks Murray,
Well thats one alternative I've been using..
Just wondering if there's a way to retain the channel mixer layer and just show/hide.

Any reason why it works so much better in RGB than CMYK?
I mean the channel mixer method to adjust/convert to B/w.

Saber, what percentages are you using in CMYK? I decided to play around with some samples, and if you keep the total percentages of the FOUR channels at 100% (as we're encouraged to do in RGB) then I think it is more likely to look washed out -- but if we think "I've got 4 channels instead of 3 to work with, I should be able to play around with higher percentages" and add another 25% to the total you can play around with -- I think you'll have more contrast.

You can also copy each of the CMYK channels as separate layers into a new CMYK document, and then use blending modes, opacity settings, and even layer masks to give you a LOT of options in creating the B/W look you want.

And then you start working with duotones, tritones, quadtones as Ant mentioned, and there are even more lovely options for end results.

[Kraellin]

i'm surprised you would get a red tint by desaturating with hue/sat. that just seems odd. nonetheless, if that's what you're getting then that's what you're getting.

try Fotomatic's 'Fast Fix' plugin. this is one i've used a lot to desaturate quickly.