What is Colour Separation?

Understanding the difference between spot and process color is extremely important when designing a job for flexography. Apart from minimizing prepress cost, the difference can effect trapping, print repeatability, color accuracy and the overall readability of any text that may knock out of the color in question.



Process Colour

Process color is the combination of different percentages of cyan, magenta, yellow and black to produce an infinite number of perceived colors. In most cases, process color is used to print multicolored imagery like the apples to the right- Objects that can’t be achieved with flat spot colours.


Spot colour is when you assign one color, or percentages of that colour, to a particular object.

process to spot 1

Spot Colour

This circle can also be designed to print 4-colour process.

process to spot 2

Process Colour Equivalent


Spot 168 is made from one plate and one station on press where as it’s process equivalent needs three plates and three stations to print on press. It is also important to note that PMS 168 is matched to a Pantone standard while it’s process equivalent is not. The process equivalent, once dot gain and registation factor in, will not always match the spot colour it was derived from.


The benefit of four colour process is that it only takes four printing plates and four stations on press to achieve an almost infinite number of colours. Percentages, or screens of cyan, yellow, magenta and black, appear as circular shaped dots under a high powered magnifying glass. These dots fluctuate in size and angle in order to achieve the wide gamut of color seen in the image below.

proc to spot 3

The figure above shows a small sampling of the image of the apples. Broken into their respective separations, each process color plays a part in creating the various shades that are printed.

proc vs spot 4

Enlarged, it is easy to see how the size and angle of each dot can create the seemingly infinite spectrum of color.



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