Microscan Quadrus MINI Imager User Manual page 83

Focus Position
Definition: Since focus can be configured by entering the target distance from the
imager's parting line, the user will normally configure the focus setting
without needing to calibrate. However, if it is necessary to calibrate the
focus distance, there are two methods for doing so: the standard "Search
Method", or a "Quick Focus" method, both of which are defined below.
<K529,gain,shutter
Serial Cmd:
WOI margin,line scan height,processing>
Default:
Quick Focus
Options: 0 = Disabled
2 = Quick Focus
Disabled
When this feature is disabled, the focus position is fixed and is not part of the calibration
process.
Enabled (Search Method)
When this feature is enabled, the focus position will be calibrated to provide the best possible
image quality and performance. This method is essentially a search method that attempts to
identify the desired focus using a search algorithm that cycles through focus settings to try
and locate the desired focus as quickly as possible. This is accomplished when the given
symbol in the field of view is decoded. Once a focus distance that will decode the given
symbol has been located, the search algorithm will fine-tune the search to locate the
"inside" and "outside" focal distances. The final focus distance will be between the "inside"
and "outside" values.
Note: This method can be time-consuming if the focus is not found on the first pass.
Quick Focus
Quick Focus is designed to quickly locate the focus setting for an object in the field of view.
This is accomplished with minimal processing of the image by analyzing a histogram of
the image frame. Before performing the focus calibration, a value for shutter speed and
gain is determined and then the calibration process will step through the focus range of the
system, capturing the required number of image frames for each focal position. A histogram
is performed on each image frame and the histogram results for each focus position are
averaged. When this process is completed, the data is analyzed and the optimal focus position
is determined.
Note: Quick Focus may not work well for all applications. It is not recommended for
applications that use very small symbols.
Quadrus MINI Imager User's Manual
speed,focus position,symbol type,WOI framing,
1 = Enabled
Calibration
4-5