Commercial Color Printing: An Illusion?

By Author: Kay Zetkin
Total Articles: 8
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Printers and designers do not have far to go if they work only in black and while printing productions. Now, there&#39s this not-quite-so new, but still ever-expanding full-color printing. Intrigued? Well you must be, because commercial color printing is quite a booming business today, what with the continuous demands on printers for high-quality, unique outputs. Not to mention, the never-ending rise of new color printing technologies. But, the color printing process does not exactly come out of the innovations themselves. They are but designed to go along with the interesting aspects of full color printing.

Understanding the world of commercial full color printing may take us a few years to grasp completely. But in a nutshell, here&#39s an introduction of the necessary concepts with regards to it.

1. Halftones -- this the simple process of adding some color even if it&#39s only gray. In this, an image setter is quite handy, although presents its problems because of being a binary digital device. It can only produce black pixels or leave white spaces. Still, there is its resolution in handy and the ...
... human eye&#39s limitation to make some tricks work. Each pixel of an imageset is smaller than the eye can resolve. Once a dot has been built up, it will be perceived as a 50% gray.

This kind of optical illusion is to break the image into a very fine grid with each square of the grid given an appropriate gray level. The imagesetter is used to simulate this gray level by creating its own grid and fills in the appropriate number of pixels. The notional grids that break the image into cells are called screens. A halftone is then created by the resulting image that gives the impression of continuous grayscales.

2. Spot Color -- it is adding some simple true color. The process is based on the simple principle of putting the page through the press more than once with a different ink each time. The colors must be kept absolutely separate so that the item being colored, e.g. the masthead, will only be printed with the colored ink while the text will only be printed black. Tippexing out all the elements to be printed in blank ink on one sheet and reversing the process on the other can be the theoretical way to produce the needed color-separated plates. Due to innovative technologies allowed for spot colors to be automatically separated.

Spot color presents 2 difficulties, though. Color accuracy due to the separated imageset output but resolved by the Pantone library. It is a printed palette with some 1,000 that are based on a precise combination of inks. Next difficulty may be developed once you get adventurous and start adding overlapping colors. The main solution for this is to set output to include registration marks.

3. Process Color -- is really the answer to how all the continuous photographs and solid colors in the magazines and brochures that surround us were created. It is the combination of the halftone and spot color effects. Apparent colors are produced through blending, rather than creating each color by blending inks, it is again done by taking advantage of the human eye&#39s limitation. Colored dots too small for the eye to distinguish are placed next to each other which makes them seem like a combined color. This combination of 3 inks, cyan, magenta and yellow produces the full range of color in printed materials we always see. 100% combination of this 3 inks makes black.

The dots were slightly offset and not placed directly on top of each other. To achieve this, the inks&#39 halftone screens were set at an angle to each other. Actually, the trick is that by blending 256 levels of each of the three coloured inks as halftone dots, the theoretical maximum of 16.8 million colours (256 x 256 x 256) is achieved. It has become a simple solution that has worked well beautifully and elegantly.

However, it also proves that a full color print is actually an optical illusion -- of blending and built on halftoning. You might think it a case of magic trick of the eye, but even as it is explained quite simply, it is still puzzling enough that you might even get the wrong solution if you tried.

Of course many other factors contribute to the whole colored output -- the quality of the paper to be used is considered a great deal in all three concepts of color printing. Another factor to be considered in full color printing is the assistive technology you are using and how innovative it could be. There you are, a few revelations on commercial color printing...isn&#39t it quite an illusion, really?

Copyright © 2005 Kay Zetkin Resource box: For comments and inquiries about the article visit http://www.colorprintingwholesale.com