How open OSC FITS file in colour?

[BrendanC]

Hi,

Subject says it all really!

I want to process lots of individual FITS files I took of Comet C/2017 K2 (PANSTARRS) last night, but when I bring them into StarTools, they're treated as mono linear files. How can I bring them in as colour? (I want to process them separately so that I can then create an animation showing the comet moving across the sky).

These are created by a ZWO ASI533MC Pro, using APT.

Thanks
Brendan

[hixx]

Hi Brendan,
To get an RGB image,You would need to run these through a stacker which is capable of demosaicing RAW files. This will create an RGB stack. Imported in StarTools, it will still look greyscale but will process color in parallel until the Color module, which marries Luminance and Color info.
The stacker will also need to be capable of Comet registration/stacking to bring out the Comet vs the stars (because the comet is moving relative to the stars, it might be at a slightly diffeent position in each Lightframe). Once correctly stacked, You will get a bright comet and light star trails in the background.
Clear Skies,
Jochen

[Mike in Rancho]

Hi Brendan,

Momentarily setting aside Jochen's tips about comets, in order to see any grayscale FITS taken with an OSC (CFA) camera, the file needs to be debayered.

There are a number of ways to do that. ASTAP can debayer a single file that is in the viewer, which you can then save back still in linear FITS. With DSS I think you can "stack" a single FITS to have it spit out a debayered file, if the RAW/FITS settings are checked off correctly.

If set up right, both ASTAP and DSS can also output each of your individual light frames, calibrated if you took calibration files, and debayered. Handy if you want to review or use single exposures without stacking, but the benefit of dark subtraction and flats correction, and in color.

[hixx]

Hi Mike, Brendan,
yes essentially debayering is a way of demosaicing RAW images taken with a Bayer matrix. Any different color Matrix (e.g. Fuji X-trans or Foveon sensors
and some OSC cameras) will require a different demosaicing scheme than Bayer.
The point is, it's the stacking software doing this "RAW demosaicing" using libraries like LIBRAW or dcRAW which will cater for the correct scheme for supported cams. If Your cam is not supported You might select the scheme manually.
Hence the hint for comet registration capabilities. Without these You would not be able to produce any useful stack, let alone the greyscale/color topic.
cheers,
Jochen

[BrendanC]

Thanks all, I figured this one too - just run the files through DSS and it's sorted.

I'd love to show you results here but I can't attach a video, so here's a link instead: https://photos.app.goo.gl/n5CSn6hgMfcpB6pM9