Have you ever wondered why the color
you believe you have created is not the color you get?
Light & Color
The primary colors are red, blue, and yellow; these colors refer
to pigment and paint rather than the spectrum of light. In fact,
the primary colors of the light spectrum are red, green and blue.
Objects appear as a certain color because they absorb some primary
colors and reflect others. A red object appears red because it
is absorbing green and blue light, while reflecting red toward
your eyes.
RGB
The RGB (Red, Green, and Blue) colors on a screen are created
by adding light to change a black appearing screen. Four color
process printing uses colored inks to partially obscure the paper's
white surface and subtract reflection of certain colors until
a desired color is visible. These two different systems are called
additive color and subtractive color. The screen is additive
color because light is added to create color. The press uses
subtractive color because inks are used to partially block the
reflection of light.
CMYK
CMYK (Cyan, Magenta, Yellow and Black) uses different percentages
of cyan, magenta, yellow and black to create or "build" color.
This technique is sometimes called screened color because screens
of each color are used to create a new color. Because process
colors are "built" from two to four inks, they sometimes look
murkier than a spot color. Some spot colors are impossible to
render through process color. Consequently, the color on the
monitor can create a number of strong colors that cannot be reproduced
in print. A conversion from RGB to CMYK is necessary for printing
process color.
RGB vs. CMYK
Remember: NEVER judge color based on what it looks like on your
monitor. One of the issues that affects color printing on a fundamental
level is the incompatibility of screen color with printed color.
Converting RGB to CMYK
RGB - Red, Green, and Blue, are the colors of your monitor.
CMYK - Cyan, Magenta, Yellow, and Black are the four process
colors used in printing.
RIP devices tend to prefer RGB - EPS images because they are
usually better at reproducing CMYK values. Some digital devices
will accept RGB images and convert them into CMYK, sometimes
with good results. But this is a little like Russian Roulette
with a paint gun, so beware. Results can be different from one
job to the next!
If you need full color printing, your files must be converted
to CMYK in order to get process color separated film.
When color is the most important issue, a color proof is a must.
A digital press, such as the Xeikon or Indigo can provide a press
proof. However, for traditional offset printing, a matchprint
or a cromalin can be expensive but are precise in rendering process
color.
Spot Color vs. Process Color
Spot Color - The use of a specific ink color on a designated
area of the sheet.
Process Color - Using CMYK and 4 halftones the press can reproduce
full color artwork beautifully.
You may combine spot color with full color photographs. In this
case, it is recommended that all spot color be converted to process
color in order to save money in the printing process.
Color Correction
Beyer Printing must convert your photographs or scanned images
to CMYK before they RIP the file to an imagesetter to obtain
film or print to a digital press. However, color correction should
be done in RGB. Here's why:
Scanners are RGB devices and will scan your image as RGB color.
It is recommended that all color correction and image manipulation
be done in the RGB mode, as monitors are also RGB devices and
will render more accurate color correction for viewing. Additionally,
RGB has less color information, so the image is a smaller size
making working with it easier and faster.
When the file is ready for printing and does not require any
further prepress, only then will your printer convert the images
to CMYK. Your printer will make a copy of the file and make the
final changes to CMYK on the copy.
