4 col. process seps.

[Rockers]

How are you all doing your 4 color process seps?
We use Union process inks so I downloaded their magic numbers and loaded them into Photoshop to use instead of their standard CMYK values. Anyway then we convert the RGB image to CMYK and the use the according channels as seps. Might do some slight curve adjustments. But that`s about it. Am I`m missing something  or are there any other ways to do it?

[Doug S]

Pretty much the way I do it.  I do most of the adjustments to the image while it's still RGB so that most of the time I don't have to touch it after I convert.

[Colin]

Always double check for color conversion "problems".  This always happens.

I.e. check yellows for blue contamination/check greens for magenta contamination etc....

Go over the image with a fine toothed eye dropper

Other than that, it's a great cmyk system.

What are your CMYK dot gain (curves)/black generation/ink limit settings?

[Dottonedan]

Always double check for color conversion "problems".  This always happens.

I.e. check yellows for blue contamination/check greens for magenta contamination etc....

Go over the image with a fine toothed eye dropper

Other than that, it's a great cmyk system.

What are your CMYK dot gain (curves)/black generation/ink limit settings?

Well, there ya go. That's the difference between conversion and loading color presets.
It's one thing to load a color set that matches the inks. That's one of the good things to do.


There is more, (when you convert the RGB - to a CMYK color setting), what does that do?


It gets pretty congested with options (and for various art). You may not want to use one RGB to CMYK conversion for dark muted colors and you may choose another setup for a very bright design with near rich (heavy %'s of straight up Cyan, Magenta etc.  It's all different.


Some people can get by (at random times) getting a fantastic result this time...not knowing why they did so well ....and other times they do a CMYK with the same settings to find that it's just not working. The color settings should be tweaked before each conversion.


To boot, you then will need to adjust manually in the channels. That can be by isolating an area with a selection and cutting it back or adding to...or it could just be by taking the 50% area and dropping it down to 40% (in each channel). I do both for most people.


I first use the conversion of my many options. I think I have about 12. Then, I review the seps, consider the mesh, consider the garment color (often white), but sometimes its light colors with a base. All of these make a difference.


For the most part, you can do pretty good with just always using UCR (Under Color Removal) but sometimes, I use GCR (Gray Component Replacement).


In general, the total ink should be about 260-270
Black ink limit should be 100.


Black generation will be in various options of MAX, Heavy, Medium and Light.
This determines really, (how much) color content is in each channel to make up the same art.


Offset printers will use something totally different than we do.

[RICK STEFANICK]

YOU GO DAN CAMPBELL.. To me that sounded like chinese but any seps i have used of yours were dead nuts on man!!!

[Rockers]

Always double check for color conversion "problems".  This always happens.

I.e. check yellows for blue contamination/check greens for magenta contamination etc....

Go over the image with a fine toothed eye dropper

Other than that, it's a great cmyk system.

What are your CMYK dot gain (curves)/black generation/ink limit settings?

Well, there ya go. That's the difference between conversion and loading color presets.
It's one thing to load a color set that matches the inks. That's one of the good things to do.


There is more, (when you convert the RGB - to a CMYK color setting), what does that do?


It gets pretty congested with options (and for various art). You may not want to use one RGB to CMYK conversion for dark muted colors and you may choose another setup for a very bright design with near rich (heavy %'s of straight up Cyan, Magenta etc.  It's all different.


Some people can get by (at random times) getting a fantastic result this time...not knowing why they did so well ....and other times they do a CMYK with the same settings to find that it's just not working. The color settings should be tweaked before each conversion.


To boot, you then will need to adjust manually in the channels. That can be by isolating an area with a selection and cutting it back or adding to...or it could just be by taking the 50% area and dropping it down to 40% (in each channel). I do both for most people.


I first use the conversion of my many options. I think I have about 12. Then, I review the seps, consider the mesh, consider the garment color (often white), but sometimes its light colors with a base. All of these make a difference.


For the most part, you can do pretty good with just always using UCR (Under Color Removal) but sometimes, I use GCR (Gray Component Replacement).


In general, the total ink should be about 260-270
Black ink limit should be 100.


Black generation will be in various options of MAX, Heavy, Medium and Light.
This determines really, (how much) color content is in each channel to make up the same art.


Offset printers will use something totally different than we do.

Question- The image I`m working on has pretty much solid areas of black. Still the CMYK channels clearly show that even in those solid black areas values of up to 50% of magenta, same for yellow and at least 25% cyan. Would you recommend to reduce those values if possoble. I can`t see why there is cmy needed anyway if it`s really just black what should print there. By the way we are talking about an image of a Panda Bear.

[Colin]

CMYK inks are very very translucent.  I.e. very low levels of pigmentation.  You can try to print just black there, but you will find the image looks "washed out" in those areas. 

So, if you end up adding the other 3 colors under it - in percentages that end up looking like mud - you can get a nice clean rich black.

The added benefit is that you also lay down a thicker deposit of ink over all - thereby increasing your fibre matte.  Which with cmyk inks, is very low to begin with.

This is the tldr version. 

I know the reasonings have been written up several times over the last few decades.

I would look and see what you can find from Mark Coudray on the topic.

Or:  Honestly - Have Dan sep your first job.  Once you get the seps back and you can see how awesome it looks, compare what your seps would look like to what he produced and learn from dissection.  The follow up with a job you guys sep and see how it goes!