Using Custom Dot gain and Ink Color Setting in Photoshop.

[russpears]

How does one use the custom color settings in Photoshop? Like the GCR and UCR, Custom Dot Gain Curves and Ink Colors. And in what circumstances might they be useful?

[langier]

All this is pertinent in a prepress environment when Photoshop is used to prepare your files for making separation negs, CTP or Di to the press. Usually, unless you are working in an offset (or similar) press or electronic prepress department, it isn't anything to worry about.

However, if you do head that direction, you are now aware of some of the hidden powertools of Photoshop! Congrats for exploring in these hidden recesses!

[russpears]

My reason for asking is that I have a new Canon Mark II printer and if I get something to measure the various densities, then I might be able to build custom color settings just as you would in prepress. Am I thinking wrongly?

[langier]

Generally, I think, if you run profiles, you don't have to get into UCR/GCR, dot gain, or other prepress techniques since you are building a LUT that translates what you see into what you print. The only changes I tend to make with my workflow very occasionally is to tweak the color, thickness and drydown in the the printer controls of the printer driver, not mess around with the images and make them only printable to me.

The goal of all this color management isn't to fool around deep in the menus, but to get as close as the technology will allow to WYSIWYG color so what you print on one printer with one set of inks on one paper is similar if the same on other printers/inks/papers.

If you don't think you'll ever change printers, papers, inks, then changing all these output settings may make sense, but be ware that you may though all your settings out of kilter.

Even when I did a lot of prepress, I seldom dealt with those settings and aspects of production since most of what I did pretty much reproduced just fine without much tweaking. But that was when my images went to film for the press. Today, I work predominately in RGB and if needed, I'll convert to CMYK if the work is going to press (post cards, brochures, catalogs) IF I'm doing the design. Otherwise, stick to RGB, get a good profiling system (I'm using the ColorMunki for both my displays and custom profiles), and spend your time crafting the best print you can!

[russpears]

You really offered wise advice here and I think it is convincing enough. However, I am curious about much of the inner workings and so I like to learn more about them. But for sure the end goal should be the focus and making all of theses color changes of one output is not being smart down the road as printing technology changes and you purchase a different printer.

One guy made a good suggestion about using UCR and GCR when printing on different surfaces in CMYK. By eliminating a channel with GCR you can avoid registration and color shifting on press.

Also what is "LUT"

[russpears]

Maybe you can lend advice on this: If I use a levels or curves adjustment in Photoshop to set a 240 black point and a 7 white point for my print, then set Photoshop to management color in my print dialogue with a black point compensation. Will this help or hurt to results?

[Nigel Johnson]

I have a new Canon Mark II printer

Russ

As far as I am aware, like most consumer inkjet printers (and large-format printers such as the iPF 8300) the Canon Mark II expects RGB data not CMYK, as such the standard Canon printer driver will either not be able to print a CMYK image or will convert it to RGB, undoing your custom colour settings (I am not certain but it may be the computer operating system or Photoshop that will do the conversion to RGB, but the effect will be the same). One of the problems you will find is that you won't be able to print out pure C, M, Y & K patches to measure.

In order to print in CMYK on your printer you would need to buy an expensive RIP, if there is one that supports your printer.

Note that the comments refer equally to printers from other manufacturers such as Epson & HP.

Regards
Nigel

PS I can understand your desire to experiment and remember trying to do this about 15 years ago using a Colortron II spectro with a dye sublimation printer, not realising that the printer only accepted RGB .

[ckimmerle]

Yup, inkjet prints require RGB, despite using inks such as cyan, magenta, black and yello. CMYK is only for commercial printing presses in which each channel is directly related to an ink.