I capture last day M13 with a Canon 450D and Ekos. The image on the screen, into the FIST Viewer, was green. Curiously the FITS image downloaded is black and white, with very little signal . In fact I can see anything and I have to improve the signal with Photoshop in order M13 appears.

So why green ?
And why such difference between the fits viewer and the fits image ?

Thank you for your support.

Maybe its the "Auto Debayer" or "3D Cube" Setting in the FITS Settings in the Kstars settings, try to disable them, maybe that helps.

Debayered DSLR images tend to be "green" since there are 2 green pixels for each Red & Blue pixels in the bayer mask. You just need to process the image in PixInsight or something similar. I don't understand what you mean by fits viewer and fits image? any links to the captured image?

Are you using a CLS filter with your DSLR? If so images debayered to RGGB and seen with Fits Viewer have a strong green cast. It's normal.
There's no white balance applied to the image so you have to color correct it in processing. If you debayer the Fits image (the black and white one) on other software you will get the same result.

I know the mask bayer RGGB. At this time, I compare my experience with those with a windows astrophoto program ATP (AstroToolsPhoto similar with Ekos). Images are captured in RAW format and were not green. Is the green color consequence of conversion RAW -> FITS ?
The second issue is, the image in the FITS viewer shows clearly the object (M13), but the image downloaded onto the HDD shows a very little signal and seems totaly black. The signal appears only with Photoshop process (Level and Curve tools). Is this differnce normal ?

As you can see I am not a pro about this imaging issues.

I didn't use filter CLS or others.

Double check the enabled/disabled settings for the FITS viewer. Settings can be found through the options button at the bottom of the CCD window.

OK kcobby, I'll try next clear night !