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A Lesson in Color Printing
Color printing is the act of reproducing an image or text in color, as opposed to black and white or monochrome (one color). Nowadays, color printing is a commonplace task that most people perform on a daily basis. In fact, full color online printing services are now readily available if you’d rather not deal with such a chore. The process of full color photo printing and full color fine art printing is a precise and detailed science.
Have you ever pondered the symbolic relationship between the computer and the printer? How is it that colors we designate on screen are able to so accurately replicate on paper? Equally as fascinating is the color copier; which is able to instantly clone and multiply our original color pieces. Who is the man behind the curtain making all of these features possible? Today’s technological machinery had the power to print custom pantone colors in full range, due to a method known as four-color process printing.
Four-color process printing is, exactly as its name suggests, a process of full color fine art printing which uses four colors—or three primary colors and one shade—cyan, magenta, and yellow, plus black. The commonly accepted abbreviation is CMYK. While four-color process printing is most typically used, six-color process printing is the new trend in full color giclee printing. Six-color adds orange and green to the CMYK model for a larger palette of vibrant color resolution.
In order to print a color image in CMYK, a series of steps must occur.
Color separation process
First, the original color piece is separated into three gray scale images of red, green, and blue (RGB) components. Next each of these components is inverted into their negative counter part. CMY are subtractive primaries. Each component of CMY represents two of the three additive primaries (RGB) after one additive primary is subtracted from white light. In other words CMY represents negative images of RGB. When inverted red transforms to cyan, green transforms to magenta, and blue transforms to yellow.Cyan, magenta, and yellow are the three main color properties used for color printing. When these three colors are combined the result should fall fairly close to the original piece. Due to the shortcomings in ink pigments, however, the darker colors of the pieces become muddled. Black is then used to fine-tune the shadow and contrast of the image. The letter “K” is used to represent black in the CMYK model. The “K” stands for “key,” because black is the key color or shade used in the RGB printing conversion process. The black separation allows accurate colors within a color model to be obtained. This is called color matching.
Screening
The next step in the custom pantone color printing process is screening. Screening essentially accounts for the fine details of a color image. In screening, lighter shades are represented as tiny dots rather than solid sections of ink. A printing press on its own cannot determine the variations of ink needed to detail an image. In the process of screening the screen grids are set at different angles. The screening dots create tiny rosettes, which, through the power of optical illusion, appear to form a continuous-tone image.
And this is how you get your finished color image in print. Now you’ll know, the next time you hit the “Print” button, exactly what’s going on amidst all that humming and whistling of the printer.
Filed under: Uncategorized, Education, Technology on January 24th, 2008