If you have two or more images of the same scene taken at different wavelengths, you may wish to combine them to create a colour composite.
For ultimate control, you can do this manually using
imview. Simply map your channels to
RGB values using
imview and then sum the results.
For convenience, AstroImages.jl provides the function
composecolors using Hubble images of the Antenae colliding galaxies.
One can be very scientific about this process, but often the goal of producing color composites is aesthetic or about highlighting certain features for public consumption.
I'll set the default color map to grayscale to avoid confusion.
using AstroImages AstroImages.set_cmap!(nothing)
Let's start by downloading the separate color channel FITS files:
antred = AstroImage(download("http://www.astro.uvic.ca/~wthompson/astroimages/fits/antenae/red.fits"))
antgreen = AstroImage(download("http://www.astro.uvic.ca/~wthompson/astroimages/fits/antenae/green.fits"))
antblue = AstroImage(download("http://www.astro.uvic.ca/~wthompson/astroimages/fits/antenae/blue.fits"))