In Print

Process printing uses the subtractive method of creating colors. Obviously, because printed matter such as magazines and newspapers don't give off their own light, they cannot support the additive color method. There are only usually 4 colors of inks used. Cyan, magenta, yellow and black. You may be wondering about the black, but we'll get to that. The reason the first 3 colors are used is simply this. The cyan reflects blue and green and absorbs red. The yellow reflects green and red light and absorbs blue. And the magenta reflects blue and red and absorbs green. Therefore you have set the stage for creating almost every color under the sun. The addition of black is simply this. When you combine the CMY colors in printing, theoretically you should get black. For details I won't get into here, you don't. You get a muddy brown. Therefore, a black ink is added to the process to neutralize that brown mud color and also provide a way to extend the printable contrast of the images.

The other thing you should know is that printing presses cannot print shades of colors. Only solid color. Imagine it being like a light switch. It's either on, or off. It either prints solid ink, or it prints nothing. So how do you accommodate varying amounts of colors, or shades you ask? Well, the answer is, you print tiny solid dots of colors. The smaller the dot, the less of that color is present and vise versa. However, to the eye, the dots are small enough that it just appears as though its a shade of that color.

One more problem in printing colors is that not as many colors can be printed in CMYK as what can be produced in RGB. Therefore you usually have some color loss going from RGB to CMYK. It's unavoidable. At least until the day that our magazines etc. are capable of giving off their own source of colored light. Until then, we'll have to rely on the surrounding light and subtractive method to allow us to see color on paper.

Notice the loss in color from the RGB image to the CMYK image. This can be quite drastic in certain colors such as a saturated blues or reds. It has been known to cause many headaches for printers and desktop color people who end up dealing with customers that just don't understand why their beautiful RGB images look flat in print. A good desktop color specialist will minimize this degradation, but will still have to live with some color loss. It's the nature of the beast.

Here is a close-up of a printed image. You could see this yourself by looking at printed material through a magnifying glass. You can see in the above image the little dots of Cyan, magenta, yellow, and black. Remember, these dots are not shades of the four colors, but strictly dots of solid ink. An offset press cannot print shades. Only solids. But tiny dots of solids allowing varying amounts of white paper to show through or other colors of inks, create the illusion of shades to the eye.