GNU Astronomy Utilities
220.127.116.11 NoiseChisel output
The default name and directory of the outputs are explained in
Automatic output. NoiseChisel’s default output (when none of the
options starting with --check or the --output option
are called) is one file ending with _labeled.fits. This file
has the extensions listed below:
- A copy of the input image, a copy is placed here for the following
- By flipping through the extensions, a user can check how accurate the
detection and segmentation process was.
- All the inputs to MakeCatalog (see MakeCatalog) are included in
this one file which makes the running of MakeCatalog after NoiseChisel
- The object/detection labels. Each pixel in the input image is given a label
in this extension, the labels start from one. If the
--onlydetection option is given, each large connected part of the
image has one label. Without that option, this extension is going to show
the labels of the objects that are found after segmentation. The total
number of labels is stored as the value to the
keyword in the header of this extension. This number is also printed in
- The clump labels when --onlydetection is not called. All the
pixels in the input image that belong to a true clump are given a positive
label in this extension. The detected regions that were not a clump are
given a negative value to clearly identify the sky noise from the diffuse
detections. The total number of clumps in this image is stored in the
NCLUMPS keyword of this extension and printed in verbose output.
If the --grownclumps option is called, or a value of
is given to it in any of the configuration files, then instead of the
original clump regions, the grown clumps will be stored in this
extension. Note that if there is only one clump (or no clumps) over a
detected region, then the whole detected region is given a label of 1.
- The final sky value on each pixel. See Sky value for a complete
- Similar to the previous mesh but for the standard deviation on each
To inspect NoiseChisel’s output, you can configure SAO DS9 in your Graphic
User Interface (GUI) to open NoiseChisel’s output as a multi-extension data
cube. This will allow you to flip through the different extensions and
visually inspect the results. This process has been described for the GNOME
GUI (most common GUI in GNU/Linux operating systems) in Viewing multiextension FITS images.
Read in other formats.
GNU Astronomy Utilities 0.4 manual, September 2017.