October 24, 2007
An Overview of Color Printing Technology
Color printing vastly improves the quality and readability of documents, particularly those that are data intensive. Color printing technology typically involves breaking the image to be printed into component colors and then recreating the image using a fixed number of ink colors (typically 4, though occasionally 6 colors are used) that, when combined, accurately recreate the image.
The first step in color printing is to separate the image into primary color (red, green, and blue) components. Modern color printing technology uses digital signal processing to separate the colors. In the days before the PC, color separation was accomplished by taking three photographs of the object through different color lenses. After the colors have been separated, a negative is produced that translates each primary color into its compliment color (for red, green, and blue we have cyan, magenta, and yellow). Color printing involves placing the cyan, magenta, and yellow on the print media in such a way as to recreate the original image. Black ink is also used in color printing for dark colors and contrast.
Screening in color printing is the act of placing the ink on the media in such a manner that the individual inks work together to form colors. Screening places tiny dots of ink at specific points on the print media. Large dots are used for areas that are rich in the ink color, and small dots are used when the concentration of the color is low. The dots are oriented differently for the different colors, so they do not directly interfere with one another. Under magnification, it is plain to see that color printing produces only discreet dots, no continuous images. However, under normal conditions the dots are not visible.