MOPEX User's Guide - IRSA

Relevant Pipelines: APEX Multiframe; APEX Single Frame
MOPEX User’s Guide
Important notes: The user has a choice of several different input images to his module, but the
choice is only partly set from within this module. The Input Type parameter gives the choice of
whether to use a data or SNR image as input, but the choice of which version of these two types
to use is set in the APEX Settings module using the parameters Use PSP To Detect, Use
Uncertainty to Detect and Use Standard Deviation to Detect. See the Input Type and Discussion
information below for a full description.
PURPOSE
Detect performs image segmentation and computes the centroids for the detected pixel
clusters. It is another instance of the same module used for outlier detection in the Mosaic
pipeline.
INPUT
Threshold Type : This parameter determines the way the image segmentation threshold is
recalculated during iterative thresholding. The threshold type does not depend on the type of
input image. See §8.3 for a description of the thresholding options.
Detection Threshold: (float) The number of sigma above the mean to be used as the initial
threshold used for cluster detection. Vary this to determine how deep the detections can go.
Detection Min Peak Fraction: (float) A candidate sub-peak must have a minimum height
above the current threshold. The height is given as the fraction of the “parent” peak height.
Allowed values are between 0.0-1.0. If not set, it is 0.0. Vary this to limit false detections on
the wings of bright sources.
Detection Min Area: (int) The minimum area (pixel) for a detected pixel cluster to be
retained; smaller clusters are discarded.
Detection Max Area: (int) The maximum area (pixels) of a detected pixel cluster before
iterative thresholding.
Extended Object Area: (int) The minimum area (pixels) to be considered an extended
object. If the number of pixels in a cluster is larger than this area, it is not split by Threshold
Type = “Peak".
Point Source Ext ract ion (APEX) 134
APEX Modules