New Feature : Stellar Colour Calibration for Live Stacking

[pastorgalactico]

Hello;
Last night, while testing the color calibration, it seems to be working very well... but I've noticed that when applying the color calibration, the peak of the histogram shifts to the far left, leaving little room for adjustment.
I've attached an image of part of the swan veil with 10 minutes of live stacking.

Regards.

Screenshot_2026-08-23-11-04-57-265_com.whatsapp.jpg (526.6 KiB) Viewed 96 times

[admin]

Hi,

yes, the shift of the histogram peaks to the left is a necessary part of properly colour balancing images. There are two main contributions to the colours of an astro image looking wrong in the raw image

1) Different sensitivities of the different colour channels - for instance, with modern cameras the green channel is often more sensitive than red/blue, leading to the raw images having a green colour cast

2) Colour in the background due to light pollution (often having an orange colour cast).

It's impossible to fix both of these with a single set of colour balancing controls since the first is a multiplicative problem and the second is additive - if you try to use the colour balance controls on the right hand side of live stacking on their own you will firstly find it very hard to get the adjustment even close, and then find that if you properly neutralize the background of the image then the star/galaxy/nebula colours are still wrong (or vice versa).

Colour calibration sets both the background subtraction for the 3 colour channels (see the separate background subtraction tab in live stacking) and also sets the normal colour balance controls. The background subtraction brings all the histogram peaks nearly (but not quite) to the left hand side - effectively removing almost all the background light pollution *and* making the colour of any remaining neutral, and fixing the sensitivity issue using the normal colour balance controls.

When used in this way, you find that you need smaller adjustments to the histogram, which take a bit of getting used to, but will soon come naturally. Make sure you use the 'Logarithmic' and maybe also 'zoom' checkboxes to see the important bit of the live stack histogram zoomed in more.

cheers,

Robin

[pastorgalactico]

Okay, thanks. I'll select the logarithmic check.

Regards.