Important Notes: Including this module does not automatically apply Bright Object Masking. The resulting bright object detection maps are only used if the Mask Bright Object box is checked in the Mosaic Interpolate module.
PURPOSE
Detect performs image segmentation (see §8.4). In the Overlap pipeline, it is used only for bright object detection - i.e. to identify bright pixels (both spurious and astronomical) that should not contribute to the background matching. Detect produces bright object detection maps.
INPUT
Detection Max Area: (int) The maximum area (pixels) of a detected pixel cluster before iterative thresholding.
Detection Min Area: (int) The minimum area (pixel) for a detected pixel cluster to be retained; smaller clusters are discarded.
Detection Threshold: (float) The number of sigma above the mean to be used as the initial threshold used for cluster detection.
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.
Detect output subdirectory: The subdirectory of <output_dir> that you wish to use for the output files. Default is Detect-overlap.
COMMAND LINE INPUT
&DETECT
Detection_Max_Area = 1000,
Detection_Min_Area = 0,
Detection_Threshold = 3,
Threshold_Type = 'simple',
&END
In Global Parameters:
DETECT_DIR = Detect-overlap
OUTPUT
Generated Fits Files (*detmap.fits): With the default parameters, these are the detection maps produced from the input images. A positive number indicates the threshold level reached for that cluster.
DISCUSSION
In the Overlappipeline, Detect is part of Bright Object Masking (set Mask Bright Object in the Mosaic Interpolate module). The detection of bright pixels is performed on the background-subtracted images (the output of the Med Filter module), which are in original pixels. The output is a set of mask images, one per input image, in which pixels corresponding to detected objects are set to a positive value. The mask images are saved in the Detect output subdirectory unless the Delete Intermediate Files option was set in the Overlap Settings module. If Mask Bright Object is set in the Mosaic Interpolate module then these masks will be used in the further processing.
