Calibrator: FM and ED dot patterns
Generic info on FM and ED screening
FM Screening
Whereas conventional screening methods place dots in a grid pattern to reproduce a continuous tone image with FM screening, tone densities are varied by placing different numbers of small dots within a given area rather than by changing the sizes of a fixed number of dots as in conventional AM screening.
Tonal characteristics are simulated by enlarging or reducing the dot size in a particular area of an image. With FM screening, the dots are dispersed in a less structured manner. Varying shades are created by the irregular frequency, or dispersal of the screening dots.
Dots seem to disappear, resulting in exceptional clarity and detail, especially effective in printing images of jewellery, fabrics, fine automobiles and skin tones. FM screening also eliminates moiré effects, color shifts and rosettes which can form in conventional halftone images.
Error diffusing (ED)
It is sometimes the case that there are visible artefacts in the resulting image. To circumvent this problem, so-called error diffusion ED techniques can be used. As the name implies, the error (difference between the exact pixel value from the original image and the approximated value being displayed in the result) is distributed to the neighbouring pixels, thus introducing a kind of “smoothing” into the dithered image. There is a computational overhead to the calculation of this screening method.
Related Articles
Dot Curve Editor Tool
The Dot Curve Editor Tool is a new addition to the Inkset-up dialog of a PMM. The button will only work when the screening is FM and more than 2 dot levels are in the print mode. This tool is in place for users with some knowledge on editing dot ...
Dot Curves: Graphs explained
In this page we'll learn how to read the graphs before making any changes to the settings. Preview Chart The top chart reflects in pixels the distribution of the dots and in particular the dot transitions and interleave between Small, Medium and ...
Screening Properties
To set the screening properties of a PrintFactory Queue Proceed as follows: Double-click the PrintFactory Queue of your choice. Make sure that the correct Queue type is selected. Click the Screening tab. For each of the color channels, check and, if ...
Dot Curves: changing dot distribution
The dot distribution can be changed by altering the curves of each dot size by pulling the curves and changing Max amount and Dot weight values Changing the dot distribution by dragging each dot curve In case where you wish to e.g. eliminate the use ...
Calibrator Screen Icon overview
Main screen Objects Spot Colors