ThermoFisher Scientific EZx, User Manual

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Filter Selection
Thermo Fisher Scientific Filter Selection D-3
REC 4132 Rev E
Some packages have dense edges like the edges of some cardboard
cartons or boxes. These edges appear as dark lines on the perimeter of
the package when viewing the product image. The edges are just as
dense as the contaminants that we are trying to find. If the edges are not
removed, sensitivity is severely compromised.
To reduce the effect of edges, add side edge masking as the first step to
the filter sequence chosen from
Table D–1 .
SEQUENCE EXAMPLES:
•
Side edge mask, Simple
•
Side edge mask, Simple, Enhanced Gradient
•
Side edge mask, Simple, Gamma
•
Side edge mask, Simple, Gamma, Gradient
•
Side edge mask, Simple, Gamma, Enhanced Gradient
Cans and cardboard cylinders present some unique challenges because
they produce X-ray images having a dark edge inside the package
perimeter.
Figure D–1. Typical X-ray Image from a Tin Can
A regular side edge mask would mask the outer edge but leave the inner
ring intact. This inner ring would cause the gradient to false trip because
the ring represents a sharp change in contrast. Sensitivity suffers because
small contaminants would not be detected without a gradient filter.
The problem cannot be eliminated but can be managed by adding a
simple filter followed by a side edge mask prior to the filter sequence
chosen from
Table D–1 .
Filter
Adjustments
for Packages
with Sharp
Corners or
Edges
Adjustments
for Cans
Outer edge of can
Dark ring from top or bottom
of the can
A A B