The first FM algorithms, called later first order FM screening, were inspired by the Floyd-Steinberg algorithm: they build a threshold map by placing the pixels to achieve a smooth, dispersed look. The obtained threshold map is then magnified to reach the needed dot size (typically using dots of 2×2, 3×3 or 4×4 pixels by 2, 3 or 4 times magnification).

First order FM screening	StudioRIP's second order FM screening

This technique has a number of disadvantages:

· The dots are squares rather than circles (inevitably distorted by the offset machines).
· The dots can be placed only at certain positions (using 2x2 pixel dots, for example, the dots can have only even coordinates). This ordered placement will cause a moiré on slight registration errors.
· The so-called ‘chessboard’ effect will appear near 50%, which will cause local plugging, and therefore unstable and noisy.

The second order FM screening techniques try to overcome the problems mentioned above. There are several different second order techniques used by RIPs, but their common characteristics are as follows:

· The dots are freely placed (avoiding moiré on registration errors).
· Typically, over 20%, the size of the dots will be grown rather than adding more dots to increase dot density.
· The chessboard effect is avoided, usually, by the so-called clustering effect.

StudioRIP has a second order stochastic screening, with a few special features:

· Smoother tints: a special filtering technique enables StudioRIP to produce very smooth tints in the AM part, suppressing considerably the specific blue noise of stochastic techniques. Individual films (and therefore the stand-alone colors) will be almost as smooth as with the traditional halftoning, and the noise will only appear on overprinted inks.

· Round dots: StudioRIP produces real round dots (if a minimum of 3×3 pixel dot grid is used), and it also optimizes the dot placement to form, when possible, rounded shapes without sharp angular corners or thin lines. 

· Different black and white dot size: a unique feature of StudioRIP’s stochastic technique is the ability to use different dot sizes in the highlights and shadows. This is useful because the dot gain of the CTP, imagesetter or press usually increases the size of the dots in the highlights, and reduces the size of the dots in the shadows (which, in extreme cases, causes the plugging effect). Using bigger dots in the shadows than in the highlights enables StudioRIP to achieve the same black and white dot size on the final printing.