Re: Color schemes, color printing

Subject: Re: Color schemes, color printing
From: Laura Lemay <lemay -at- DEATH -dot- KALEIDA -dot- COM>
Date: Wed, 2 Mar 1994 09:27:45 +0800

>Can anyone recommend references that explain the various color schemes, such
>as CMYK, Pantone, etc., that are used in DTP and graphics apps on PCs?

Any good graphic design or graphic production book should explain each of
these, but here's a summary:

RGB = Red, Green, Blue -- the color standard that's used on your monitor.
All the colors on the monitor are some combination of these colors, which
are additive, meaning that full amounts of all three add up to white.

CMYK = Cyan, Magenta, Yellow, Black -- what are called process colors,
Most color printers use a CMYK model. CMYK colors are subtractive --
if you take all the red out of a picture, you get cyan in the negative.
If you take all the blue out of the picture, you get yellow in the
negative, and so on (its the sort of thing thats very easy to explain with
pictures, and a real pain to describe in text).

Pantones are printing inks -- more on that later.

The practical part of color models is trying to match up the RGB model
on the screen when you lay out your color work, and then see what happens
when you print it using the CMYK model. Generally the results are
drastically differerent.

So how can you assure that the color you're going to get on the screen
is going to be the color that you get on the printer?

The answer is, you can't. There are systems that will calibrate
your screen to your printer (and most DTP software should have some method
of doing simple calibration), but the essential problem is that light
reflects differently off of colors on the screen than it does on the
printed page. Not to mention the fact that differerent monitors, different
printers, and even different papers represent color in different ways.
So, once you get the colors right on your in-house proofs, once you send the
document out to the print shop, everything will be all wrong again.

There are three solutions that I've seen --

- you can often get close to the colors you want by using software
calibration. Most of the bigger DTP software packages allow you
to calibrate screen color with printer color. its not great. But
if you're not overly concerned with exact matches, then this will work.

- you can do extensive page proofs using the final printer output. A
writer friend who was involved in a software manual for a color printer
had to spend *three* *days*, full time, at the printer in Utah, waiting for
page proofs for about a dozen reasonably complex color pictures, making
corrections with the operator, and then waiting for printout again.

- The third way, if you're doing spot color, or color drawings, as opposed
to full photographic layout, is to print seperate proofs for each color
on the page (for example, one for just the text, and one for the spot
color), and then tell your print shop exactly which Pantone color to use for
each seperation (this, of course, only works if you're working through a print

Pantones are printing inks, in a wide assortment of colors. Each number
corresponds to a tube of ink, so if you tell your print shop to use Pantone
#86 for your callouts, you're certain to get *exactly* that shade. When
I work with designers, usually when they hand over the final pasteboard
they write the pantone numbers on the transparent cover for the design.
With those numbers, its usually very easy to get quality results from
the print shop.

I've seen some DTP and illustration programs that try and give you pantones
on the screen. I suppose thats useful in some ways, but again, if you're
trying to measure by eye whether two colors look good together, you simply
can't do it on the screen.


I'll leave it up to someone else to compare color printers -- I'm not up
on the current technology, and most of my color work has been through
a print shop instead of in-house. I know that MacUser, in thier most
recent issue, did a big comparison of color printers for the Mac that
may be useful to you.

good luck;

Laura, tech writer

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