Demosaic Bayer FITS files and convert them to color TIFF
There is no handy tool for converting FITS files on macOS and Linux. Learn how to use Python to demomosate Bayer FITS files and convert them to TIFF format that can be edited in Photoshop.
Shooting environment
--Camera - ZWO ASI 294MC --Control software - KStars + Ekos
The Bayer pattern for the ZWO ASI 294MC is RGGB.
Environment
Use Astropy to read the FITS file and OpenCV for image processing. The package version at the time of writing is as follows.
- anaconda3-2020.02
- opencv (4.1.0)
- astropy (4.0.1.post1)
processing
Let's process the image of the moon (moon.fits) taken with a telescope.
1. Open FITS file
from astropy.io import fits
hdul = fits.open('moon.fits')
src = hdul[0].data
At this stage, the Bayer array remains, so it is a monochrome mosaic image.
2. Demosaic / Save
Restore a color image by specifying a Bayer transform with the cvtColor function.
import cv2
dst = cv2.cvtColor(src, cv2.COLOR_BayerBG2BGR)
cv2.imwrite('moon.tif', dst)
The following TIFF image was output. You can adjust the brightness and color balance with any image editing software.
3. Editing example in Photoshop
Level correction, color balance adjustment, and sharpening filter applied.
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