Pattern Removal Auto; Monochrome Cameras - Basler acA2040-55 User Manual

AW00123409000
You can also use the Basler pylon Viewer application to easily set the parameters.
For more information about the pylon API and the pylon Viewer, see Section 3.1 on
For general information about auto functions, see Section 7.15 on
For information about Auto Function ROIs and how to set them, see Section 7.15.3 on

7.15.8 Pattern Removal Auto

7.15.8.1 Monochrome Cameras

As a result of the camera's sensor design, images output by the monochrome acA3800-14um
cameras can display a superposed artifact pattern resembling a checker pattern.
You can suppress the formation of the "checker pattern" to a great extent (pattern removal) by
ensuring that the appropriate correction coefficients are applied to the original pixel values.
Correction coefficients are automatically applied with each image acquisition and their application
can not be disabled. Pattern Removal Auto is the auto function that allows you to ensure that the
values of the correction coefficients are appropriate for each image acquisition. The values are only
valid for the specific imaging conditions (see below) that were present when the correction
coefficients were configured using Pattern Removal Auto.
The checker pattern originates from details of the sensor design: Neighboring pixels forming groups
of four will respond identically to light only if its incidence is perpendicular to the sensor's surface.
If the light arrives at an oblique angle, the four pixels of each group will respond slightly differently,
giving raise to the checker pattern in the image.
When to Use Pattern Removal Auto
Several conditions ("imaging conditions"; see below) govern the occurrence of the artifact checker
pattern. Accordingly, for nearly complete checker pattern removal, you must ensure that the
correction coefficient values are appropriate for the current imaging conditions: Whenever at least
one of the relevant imaging conditions changes you must use the Pattern Removal Auto Function
to generate new correction coefficient values. Otherwise, values are used that are most likely
invalid. In this case the checker pattern is not or only to a limited extent removed while pixel values
are modified to some unknown and unwanted extents.
You must therefore generate new correction coefficient values when you enable or change one or
more of the relevant "imaging conditions": Among them are the following:
Optical system: exchange of lens, change of aperture, change of focus

Illumination: change of the type of illumination, change of the arrangement of light sources,

change of brightness
Camera settings and features: The checker pattern depends on several camera settings and

features, in particular exposure time, Black Level, Digital Shift, Binning Horizontal, Binning
Vertical, LUT, some image ROI-related settings (Width, Height, OffsetX, OffsetY, CenterX,
CenterY).
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