moire pattern

to anyone who knows more about printing....

help please....
in printing there will always be moire pattern (rosette pattern), example: i had four dot screens, CMYK, where the Y is 15 degrees apart from C and M, how do i calculate the area of the pattern.

 

wow I havent seen a morie in years....well correct screen angles>>

Moirés can also be created through incorrect screen angle settings in color printing. Usually, page-layout programs, which are used to import photos into page layouts, set default angles which will print correctly. Occasionally, a printer will have their own preference of screen angles and a moiré can occur.

The standard process printing screen angles are Cyan = 105û, Magenta = 75û, Yellow = 90û and Black = 45û. The important thing to remember is that each color must have a distinctive screen angle of its own. These angles are unique and will help avoid an unpleasant moiré pattern.

 

Moiré can occur even if the screen angles are correct. Examples can include close up pics of satin or other textiles with a tiny repeating pattern, more usual to find it when a scan of a previously printed original is reprinted without any descreening.

The rosette pattern is generated by the imaging device (imagesetter/platesetter). The pattern is generally referred to as clear-centrered Euclidian. You can opt for stochastic screening to eliminate the rosette pattern if you have deep pockets

 

yellow should be in 0 or 90 degrees