Quality assessment of images in the stack

Doesn't anyone have an opinion on this? 😟 

Hi @minusman,

Quality calculations are revised after each step.

So after 3) Analyse stars, only the star count in the whole image and their median shape (size and roundness) determines the quality score since this is the only thing that we know after that step.

After registration, possible image scale differences are taken into account, so if you shot the data with different camera's, telescopes or sensor binning, APP uses the registration parameters to correct the quality scores that we had after step 3. Furthermore, yes, the registration parameters allow us to use the same area/field of view as the reference frame to correct the other frame scores using the same area as the reference frame area.

Finally after normalization, so images registered and corrected for illumination differences, noise values are also added to the final quality score of the frames.

We will publish the exact formula in the manual that is coming...

Mabula

Hi,

Could I ask a follow up question?  I understand that the quality scores of the images calculated by 3) Analyse Stars are used to select the best one as the Reference Frame.  Does APP use the recalculated quality scores for the frames in 4) Register or 5) Normalize for any purpose?

Thanks, Jeff

Hi Mabula, thanks for the reply. I just do not know yet which reference range is meant.
1. whole reference frame (green area)

2. or only the area where the images overlap (red rectangle)

Option 2 would have the advantage that one can judge the transparency (by clouds, light pollution, etc.) of the individual frames in relation to the reference frame better on the basis of the star number.
The images above serve only as an example.

Or am I wrong?

With kind regards