No Curves Histrogram on Master Selection - Astrophotography

[kgunessee]

Hello,

I'm hoping somebody can shed some light on this. I'm trying to edit an astro stack, however when I apply a curves adjustment, (manually or adjusting the automatically applied one during the stack) there is either no or very little histrogram data, despite the standard histogram working as normal, and other adjustments such as levels working fine too.

While the master selection in curves isn't working, the red green and blue are, as well as grey and so on.

I have a pretty decent Windows machine so performance isn't an issue. I thought it may take a short while for the histogram to render in but it never does.

Funnily enough, I downloaded a sample stack online of the same subject, same document settings (32 bit etc), and it seemed to work on that image, so I'm at a loss.

Any help would be appreciated. I've attached screenshots and my project file for reference.

Thanks

452161177_TestStack.afphoto

[Dan C]

Hi @kgunessee,

Welcome to the Affinity Forums

14 hours ago, kgunessee said:

While the master selection in curves isn't working, the red green and blue are, as well as grey and so on.

As far as I'm aware, I believe that this is working as expected, 'Master' will show the area of the Histogram where all 3 channels overlap. 

For the image in your document, there is only a small amount of 'channel overlap' and this is what you're seeing in the Curves adjustment -

14 hours ago, kgunessee said:

Funnily enough, I downloaded a sample stack online of the same subject, same document settings (32 bit etc), and it seemed to work on that image, so I'm at a loss.

I suspect with these other samples, the channel overlap was much larger and this is what you were seeing - but if you'd like to include a copy of this file also I can double check and confirm this for you?

I hope this clears things up!