Two serious errors that occur while changing printing quality - Part 1

In printing, we deal with a world of Halftones or Dots. By putting together many Halftones, you will get a Matrix or Screen, and that Matrix will play a key role in determining the printing quality. Considering various criteria, if you don’t choose the right angle for the Dots and Halftones, your final print will receive a lot of damage.

here we will point out two factors that must be considered regarding the Matrix of Dots, and you will see how this definition would affect the Matrix of Dots and the quality of the final print. it is part one and about MOIRE:

1- Moire

While printing, the goal is to create a visual illusion. By putting together many Dots, you create an illusion that the picture you are watching has harmony or a Continuous Tone; therefore, the correct arrangement, the number, and the density of Dots are essential to have a perceivable surface. Now you must take into account that these Dots are made by lithography using a specific software called RIP; consequently, the graphic designer has no direct role in the process of making them.

A practical example: imagine we have two Matrices of Dots placed above each other. We try to rotate one Matrix and keep the other one standstill at an angle of zero degrees. The Rotation of one Matrix will affect the inner dots, and this will change the structure of the two superposed Matrices.

The resulted texture, which is called Moire, will be see able. We increase the span angle of the second Matrix until we can identify a beautiful texture called Rosette. The new texture won’t cause any disharmony. Also, the continuous perception of dots and the proper percipience of the picture will be easier than before. In conclusion, Rosette is a kind of Moire pleasant to the eyes.

The process of turning a file into some Dots that a printer can read and operate is called Halftoning or Screening.

Consider the matrix rotation of the four primary colors. Every CMYK color used in a printing process has a matrix of Dots and a specific rotation rate. Several experiments have proved that every color’s Dot must be at a specific variance with the other color so that the development of the Rosette would be accurate.

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