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ccdslice - takes slices and/or re-orient an image cube


ccdslice [parameter=value] ...


ccdslice takes slices from an image cube, along any (orthogonal) axis and can thereby also reorder the axes, or remove a redundant axis.

A chain of ccdslice has to be applied if the first (x) or second (y) axis needs to be reduced but the ordering of the cube coordinates to remain the same (see EXAMPLES below), see also ccdsub(1NEMO) for a better alternative.

ccdfits(1NEMO) can also remove redundant ("dummy") axes when writing out a fits(5NEMO) file.

Using the zslabs= keyword one or more sections based on the WCS along that axis can be selected, but for a regular selection (e.g. 30:50:2) it will do the right thing.


The following parameters are recognized in order; they may be given in any order if the keyword is also given. Use --help to confirm this man page is up to date.
Input filename, in image(5NEMO) format. [no default]
Output filename [no default]
Slice variable (x, y, or z), along which axis the cube is sliced. This axis will then become the 3rd axis. [z].
Slices to select. Multiple planes can be selected, but must be in the range 1..NzvaR. If none given, all planes will be selected. Any nemoinp(1NEMO) expression can be given, but only regular ranges will result in a correct coordinate system. Default: the whole zvar axis is extracted.
Pairs of a Zmin,Zmax pairs in WCS to be selected. Default: not used.
Scaling applied to zslabs to match the WCS in the header. Default: 1
A boolean to signify of the selected planes are selected for output (t) or the ones to ignore for output (f) - Not Implemented yet.


Here is a cube, in which only the 2nd plane (z=1) is selected, the output
    ccdslice cube.out z 2
here is a cube which is re-oriented in YZX:
    ccdslice cube.out x
and here a somewhat cumbersome three-step process to select a subset of the X axis, but leaving the cube intact:
    ccdslice - x 2:10:2 | ccdslice - - x | ccdslice - cube.out x
and the same for selecting a subset of the Y axis, now in two steps:

ccdslice - y 2:10:2 | ccdslice - cube.out y

Here an example to select some ranges in Z, where the input FITS file is in m/s, but the selection is done in km/s. After this a noise map is computed for the selected planes:

    fitsccd cube.fits - | ccdslice - - zslabs=100,200,500,600 zscale=1000 | ccdmom
- cube.mom2 mom=-2


This code depends on the fact that the data is 3-dimensional, i.e. an image cube. This is a limitation of the image(5NEMO) format.

The coordinate system description of the new zvar axis can easily be corrupted by choosing an irregular layout with xrange=.

See Also

ccdsub(1NEMO) , ccdfits(1NEMO) , image(5NEMO) , fits(5NEMO)


Peter Teuben

Update History

6-May-95    V1.0 Created        PJT
27-feb-2021    V1.2  add zslabs= and zscale=    PJT
11-may-2023    V1.3  better WCS handling    PJT

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