By: Mosè Giordano

Re-posted from: http://giordano.github.io/blog/2018-03-22-astroimages/

In the last days I worked on a very little
package: AstroImages.jl.
Written in the Julia programming language and part of
the JuliaAstro organization, this package
provides simple tools to visualize astronomical images saved
in FITS files.

AstroImages.jl is meant as an interface to popular Julia packages
like Images.jl
and Plots.jl, and
uses FITSIO.jl to read FITS files.

Currently the package supports only single-frame images, in gray scale.

AstroImages.jl is licensed under the MIT “Expat” License.

Installation

The package is available for Julia 0.6 but not yet registered, thus if you would
like to try it out use the following command in the Julia REPL:

julia> Pkg.clone("https://github.com/JuliaAstro/AstroImages.jl")

Usage

After installing the package, you can start using it with

julia> using AstroImages

For the time being the package provides only two functions:

• load (extending the load function
  from FileIO.jl), to load an
  extension of a FITS file
• AstroImage, a type constructor to create a new astronomical image object.

Reading extensions from FITS file

You can load and read the the first extension of a FITS file with load:

julia> load("file.fits")
1300×1200 Array{UInt16,2}:
[...]

The second, optional, argument of this load method is the number of the
extension to read. Read the third extension of the file with:

julia> load("file.fits", 3)
1300×1200 Array{UInt16,2}:
[...]

AstroImage type

The package provides a new type, AstroImage to integrate FITS images with
Julia packages for plotting and image processing. The AstroImage function has
the same syntax as load. This command:

julia> img = AstroImage("file.fits")
AstroImages.AstroImage{UInt16,ColorTypes.Gray}[...]

will read the first extension from the file.fits.

If you are working in a Jupyter notebook, an
AstroImage object is automatically rendered as a PNG image:

Plotting an AstroImage

An AstroImage object can be plotted with the Plots.jl package. Just use

julia> using Plots

julia> plot(img)

and the image will be displayed as a heatmap using your favorite backend.

Feedback welcome

If you test the package and would like to suggest improvements, feel free to
file an issue on GitHub or, even better, send a pull request to add new features
yourself!