Color is a serious problem because the people who wrote high-end graphics design software (Adobe Indesign®, Adobe Illustrator®, CorelDraw® and others) did not understand certain concepts of color management. As a result, they made a serious error that is problematic for graphic designers.
There are several color systems that are used in graphics design. The most common ones are RGB (red, green, blue), used to create video images such as for Websites; CMYK (cyan, magenta, yellow, black), used to create four-color process images for printing; and spot colors.
Spot color is a method of specifying and printing colors in which each color is printed with its own ink. In contrast, process color printing uses four inks (cyan, magenta, yellow, and black) to produce all other colors. Spot color printing is effective when the printed matter contains only one, two, or three different colors, but it becomes prohibitively expensive for more colors.
Spot colors are the problem. The authority on spot color inks is Pantone, Inc. It has a system (PMS) in which color is designated by a three or four digit number. To help users of the system select colors, the company prints a book of color samples. Unlike paint, that has the texture built into the liquid (gloss, semi-gloss, flat, etc.) all ink is the same. The appearance of the ink, however, depends on the type of paper stock (coated, uncoated, etc.) to which it is applied.
In its swatch book, Pantone distinguishes the differences in appearance of a color by means of a suffix (C for coated, U for uncoated). Let me say that again: The suffixes only represent the apparent color; the ink is exactly the same; the sole purpose of the suffix is to identify the swatch in the sample book.
For example, PMS 185C and PMS 185U are the same color red. In fact, if you use PMS 185U and print it from your computer on glossy photo paper, it will look exactly like PMS 185C. PMS colors also will look the same on the computer screen regardless of suffix.
So where is the problem? Apparently, when programmers examined the printed book of ink samples, they did not understand that the suffixes were merely an added feature for the sample book only. The sole purpose of these suffixes was to make it easy for the reader to distinguish between those swatches that were printed on coated paper and those that were printed on plain paper, even though the distinctions were patently obvious.
As a result of this misunderstanding, graphic designers have problems with color images and colored text that were created by different artists when they are combined into the same computer file. Images created by the same designer can also be a problem if they were created with different color palettes or were created using different software.
Sadly, all graphic design software will treat two colors with the same number but different suffixes as two different colors when generating color separations. This means that when working with spot colors, graphic designers have the tedious task of eliminating duplication of colors within the same file.
Accordingly, software creators need to eliminate the distinction between one suffix and another, but this is not likely to happen.