Bug 460040 - Variable HFR values
Summary: Variable HFR values
Status: REPORTED
Alias: None
Product: kstars
Classification: Applications
Component: general (show other bugs)
Version: 3.6.1
Platform: Other Other
: NOR normal
Target Milestone: ---
Assignee: Jasem Mutlaq
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2022-10-06 09:47 UTC by Jean-Claude
Modified: 2022-10-30 07:06 UTC (History)
0 users

See Also:
Latest Commit:
Version Fixed In:

Attachments
HFR = 3.93 (2.48 MB, application/pdf)
2022-10-06 09:47 UTC, Jean-Claude 		Details
Variable HFR values (394.62 KB, application/zip)
2022-10-28 08:16 UTC, Jean-Claude 		Details
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Description Jean-Claude 2022-10-06 09:47:04 UTC 
Created attachment 152612 [details]
HFR = 3.93

SUMMARY
During a session , recorded images are displayed in the FITS Viewer with their HFR value.
But if the SAME image is read immediately after in the FITS Viewer its HFR value is different .
Why ?


STEPS TO REPRODUCE
1. Record an image and note its HFR
2. Open the same image 
3. It has now a different HFR

OBSERVED RESULT


EXPECTED RESULT


SOFTWARE/OS VERSIONS
Windows: 
macOS: 11.7.6
Linux/KDE Plasma: 
(available in About System)
KDE Plasma Version: 
KDE Frameworks Version: 
Qt Version: 

ADDITIONAL INFORMATION
Comment 1 Jean-Claude 2022-10-28 08:16:48 UTC 
Created attachment 153253 [details]
Variable HFR values
Comment 2 Jasem Mutlaq 2022-10-30 06:02:08 UTC 
I believe this is because different algorithms are used to measure. Some only examine a small area in the image to measure HFR, others measure HFR in all the stars and take an average.
Comment 3 Jean-Claude 2022-10-30 06:55:01 UTC 
Your explanation could be valid : in my attachment, the "Just recorded image" uses 1747 stars while the "Same image read from disk" uses only 244 stars.
But why not using the SAME algorithm ? This is confusing !
Comment 4 Jasem Mutlaq 2022-10-30 07:06:31 UTC 
Good question, it comes down to performance issues. This might not matter on very fast computers, but it makes a big different on limited hardware.