Difference page (Source Extraction)
The Difference page of the
Source Extraction configures source list
differencing for the
Extract Sources command. When extracting from
an image set, source list differencing removes sources that pass
all the filtering criteria but are not located at the same
coordinates in every image. In other words, this processing step
produces a final list including only those objects that are found
in some images but not in every image of the image set. Only the
source coordinates are used as a matching criterion and properties
such as intensity or shape are not involved. The Tolerance and Matching
Region Properties control the area searched to establish
whether there exists a coordinate match at each object location.
Depending upon the application, you may or may not need to register
the images before using source differencing.
Differencing Properties
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Matching Region
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Specifies the shape of the region used to
determine whether objects in each pair of images refers to the same
object. The tolerance determines the
size of the region.
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Tolerance
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The size of the region examined for object matching.
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Max Detections
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Specifies the number of images in which the source
must be detected to be included in the final list. If a source is
detected in more images than specified, then it is not included in
the final list. This is useful for detection of moving objects. For
example, if Max Detections = 2, and
the object is detected at the same location in more than 2 images,
then it is discarded from the final list.
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Comparison with Matching
This operation is the complement of the
matching operation, meaning that objects not matched
are differenced. However, this method gives a slightly different
result than the simple "set complement" because Matching
requires an object to be located in every image whereas
Differencing identifies objects that are not matched in a
subset of the entire image set.
Related Topics
Extract Sources command
Source Extraction Properties
Mira Pro x64 8.71 User's Guide, Copyright Ⓒ 2024 Mirametrics, Inc.
All Rights Reserved.
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