CMYK Press Setup for Inkjet?

[sk_arts]

Can i use the CMYK setup tables and curves with the XY or LAB readings

from a photodensitometer, work in CMYK Preview and obtain a proper soft

proof provided that my monitor is properly calibrated to middle grey?

 

I HATE open loop systems, I never seem to set them up right. I've read the

very best books and studied under some of the leading names in digital

darkroom. Since only I use my system, I scan all my stuff (or will once i get my

scanner) and output to my printer alone, and when I do send to a service

beurow I certainly don't trust profiling enough, nor do I trust my provider has it

set up right so i send a proof along with a profiled file anyway. I see no reason

to try to set up an open loop system in this case?

 

I'd prob keep my half-reared attempt on an open loop, but rely on a closed

system, is there any reason this would be impossible, should i invest

thousands in all the necissary calibration toys?

[andy_piper2]

Most inkjet printers do their own conversion of RGB data to CcMmYK(k) data for the printer. Give them anything else (CMYK, Lab, etc.) and the driver will just convert it to RGB, and then reconvert it to its own preferred CMYK equivalents. Which adds to the print-spooling/printing time, and throws away most of your effort. And usually looks much worse than straight RGB data, as well.

 

The CMYK setups work fine if you're printing to a plate-making machine for offset-press reproduction, or saving a file to make separations to eventually produce printing plates via Quark or InDesign or some such. To consumer inkjet printer/drivers they're just so much garbage.

 

I get the best color results just using plain ol' Photoshop color management: RGB files, color profiles for the paper I'm using, print button. Others like to use Epson's color controls in Page Setup instead. But in either case, trying to outsmart the basic workflow the printers are designed for and expect is usually counterproductive, at best.

 

The newspaper I work at has spent long hours setting up an old Epson 3000 to accept CMYK data for hard-proofing pictures (which sounds like your intent). What they get (and want) is newspaper-quality reproduction on newsprint - fine for their purpose - but not the quality of prints I'd want to exhibit!

 

"Never try to teach a pig to sing - it wastes your time and annoys the pig." Lazarus Long in "Time Enough for Love" by Robert A. Heinlein

[sk_arts]

Andy-

I do not think you understood, I plan to remain in RGB with CMYK *preview*

using the primaries and secondaries as registered from my inkjet printer. to

build that preview.

 

Working in CMYK preview has many advantages over working in CMYK in

any setting.

 

If I understand it properly, you can make C register as anything, heck, even

Red if you wanted to.

 

BUT- looking about photoshop I realised that you can set up a proof based on

your printers profile. I guess getting a swatchreader would make more

sense...

[steven_clark]

I would say don't work in CMYK and expect anything resembling consistent color management. Mathematicly the K channel is a redundant degree of freedom that is hard to decide on how to control. Methods for generating the black channel vary too much. All those nice 3-component coordinate mappings and transformations that make color matching possible don't work out so nicely with 4 component vectors. At least that's my reasoning.

 

I'd say don't use CMYK unless you are doing prepress. If you've got the instrument use it to generate some good color profiles and don't try to reinvent the wheel through CMYK on an inkjet.

 

If you're really ambitious write your own software for making the profiles. I know a guy on campus who does it that way and he says it isn't all that hard.

[andy_piper2]

Ahaa! Yes. Back in my PS 3.0 days, (no profiles - no color spaces) I used to use "CMYK Preview" occasionally, and sometimes it did give me a better idea of how the final print would look - or at least some of the gamut-bending colors.

 

I've tried the print preview (command- or control-Y) setting a few times, using both printer profiles and default CMYK, but it rarely does a better job of 'previewing' my prints than just my normal monitor view. But some people here swear by it.

 

Sorry for the confusion.

[sk_arts]

Steven-

 

If using a swatch reader, wouldn't a generated profile simply do that, make a

profile and force the soft proof into the RGB color space, no matter how "hifi"

the printer is, even if it had 3 million inks to generate from? You can even soft

proof other RGB profiles in the "view>>proof setup". For instance, you can get

a profile from your friends computer and see what your photo would look liek

on his screen, though I am not sure why you would want to do that.

 

Modern swatch readers take over 64-samples, wouldn't that provide enough

samples to gain a profile which is <97% accurate??

 

The reason it is always best to work in RGB proofed in CMYK Preview is

because you can push colors into gamut to your liking, and not let the

computer do it for you which is often quite clumsy.

[sk_arts]

<<RGB proofed in CMYK Preview>>

 

This is a little confusing, I meant "RGB soft proofed in CMYK or Custom

previews"

[kevinconnery]

If you have a decent printer profile, and your monitor is properly calibrated and profiled, the Soft Proofing function works VERY well.<p>

A lousy profile, for either the printer or the monitor, will make softproofing of very limited value.<p>

Using "generic" CMYK to proof an inkjet--whether it's a 4-color or 7-color one--won't help much. How the "CMYK preview" will work will depend on how you have your CMYK set up, as you note, but it'll be a whole lot more work to get an accurate setup for your printer than it would be to simply profile the printer itself, as it's based on an incorrect model. It can (probably) be done well enough to make kinda-sorta estimates, but if you took the same time and just made test prints, you could probably get an equivalent mental picture just from the samples than you would using pseudo-softproofing.

[sk_arts]

Kevin, this is why i am looking into the xRite automated spectrophotometer

and an xRite monitor profiler.

[ethan hansen]

anno,

 

The problem with the approach you are out to use is that you likely have no control over the individual ink densities on your inkjet. If you are using a fancy RIP, then you may be able to. If you are using a six or seven color ink jet, then it becomes more difficult still.

 

You can try to measure the ink colors for C, M, Y, MY, CY, CM, CMY, paper white, and K and plug these into the custom CMYK dialog in Photoshop. As Andy pointed out, however, you really have no idea what the printer was told to print. With most inkjet drivers, when you send CMYK input it is first converted (usually very poorly) to RGB and then back to C©M(m)YK(k) again. Even if you tell it to print C, you may well get other colors in the mix.

 

You can test this. Make a CMYK document. Make two squares; fill the first with C=M=Y=0, K=100. Fill the second with C=M=Y=100, K=0. Print it. Do the squares appear identical? If so, your printer is performing an intermediate CMYK conversion and this is all a waste of time. If the C=M=Y=100, K=0 square prints as a muddy brown, then your printer accepts CMYK without translation.

 

If you have control over the ink percentages, print ramps with 2, 4, 6, 8, 10, 20, 30, 40, 50, 60, 70, 80, and 90 percent inks. Measure these to find the dot gain. Plug these values into the custom CMYK settings and you will have a reasonably accurate profile for *simulation only*. Do not use this "profile" to convert your files to -- the results will be really screwy.

 

There are still big problems here. First, what is calibrating a monitor to middle gray? Being able to trust what your monitor shows requires two a display that is not only calibrated (black and white points set up optimally, RGB gains adjusted to get the correct monitor white point, RGB gamma values adjusted to produce neutral colors over the black to white range) but profiled as well. If you are looking at color images you need some control over how colors are rendered on your monitor. Plunk down the $240 an Eye-One Display costs and you'll be set.

 

The next problem comes when you send a proof to your service bureau. If you do not have accurate profiles for both their printer and yours, this is a very simple process. Convert your images to the service bureau profile using the rendering intent that looks best. Next, convert to your inkjet profile using Absolute Colorimetric rendering. Print.

 

Without a profile for your service bureau you are back to color by number. I would recommend going to a lab with a clue instead. Without a profile for your printer, your service bureau should refuse to guarantee any matching to your inkjet print. Your desktop job will have a wider color range than any four color press. Colors your printer can easily achieve simply can not be reproduced without spot colors or a multi-color printer.

 

Profiles give you your closed loop system. Profiling your monitor is easy and relatively cheap. Profiling your inkjet will cost about $50 per paper if you contract it out, or you can plunk down $1400 for an Eye-One Photo and have at it. The latter gives you the most options.

[sk_arts]

Ethan-

 

I was stuck thinking I was a few versions down from PS7 ... this post isn't really

relivant anymore. Thanks for you input ;)