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Training for Reproducible Color

(December 2001) posted on Fri Jan 18, 2002

Today, promotional graphics demand process color. Can your screen-printing shop deliver?

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By Bruce Ridge

Each of these problem areas involves circumstances that are unique to screen printing, so process-color training must be similarly specific to the process. However, there are basic principles that apply to all color-reproduction methods, and these fundamentals must also be addressed. The most important of these process color basics are described in the following sections.

Additive and subtractive color theory We have all learned from an early age to understand color as if all color is created from opaque paints. One of the first hurdles to understanding the way process color works it to understand that color is a product of light. We find that most of the people working in art departments understand this since they frequently view images in an RGB mode on their monitors, then convert the image to CMYK for printing. But once the image leaves the art room, most of the other people in the shop don't understand the importance of how additive (transmitted) and subtractive (reflected) color come together in print reproduction. The role of light in color perception is clearly evident from the confusion that results when a color appears to change because the image is being printed on a different substrate or the graphic is viewed under different lighting than originally.

Proper viewing distance Many screen printers are constantly being pushed by their clients to print halftones at higher line counts. This is the fall out we get when our customers have been working with offset lithographers, who compete with one another on a higher-line-count-is-better basis. But screen printers face a major obstacle in printing higher line counts: mesh interference, which compresses the reproducible tonal range and color gamut we can achieve.

Now consider what happens if the graphic is being reproduced as a medium or large-format piece. To support a high halftone line count, the digital artwork needs to have a high resolution at the desired image size. This leads to huge graphic files that are difficult to store, transmit, and manipulate.


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