*What are Traditional and Frequency Modulated (FM) Screening?
Traditional screening, in which the size of the dots varies but the distance between them remains constant, relies on calculated angles and frequencies that produce a simulation of continuous tone color when screens of the four colors (CMYK) are printed together. If there is interference between two or more of the screens, a Moiré pattern occurs. Interference may result from badly created screens or from the nature of the image itself (if the image contains repetitive patterns, such as certain textiles or offset printed materials).

---In FM screening the distance from dot to dot varies, while the dot size remains constant, and the appearance of patterns is avoided by fitting the edges together very smoothly when a tile is repeated.
In FM screening, however, the number of gray levels is no longer closely tied to the resolution. This reduces the size of the files and thus reduces the time needed to process these files. It also eliminates color banding and gives accurate and increased tonal range.

---With traditional screening print time is lost trying to establish the correct ink-water balance. Because dots vary in size, smaller ones become saturated with ink before larger ones. With FM screening, because dots are the same size, this problem does not occur.

---Market feedback indicates that FM screening is now generally accepted as a higher quality, more productive way to offset colour printing.