Why do we stack frames?
Posted: Fri Aug 02, 2019 11:00 am
The data is a set of 100 lights (60s exposure, gain 200, black_level (offset) 30), 60 darks, 100 bias, 100 flats taken with an Altair 183C + Vixen 81s refractor. The master dark, bias and flats were created once and used thoughout the test. A single, 2, 5, 10, 25, 50 and 100 stacks were created. The software used was Siril. Each stack was processed in exactly the same way - crop, background extraction, colour calibration, colour saturation, remove green, noise, histogram transformation, save as PNG (all mouse clicks on pre-defined values and no 'playing around with sliders'). The PNGs were reduced to 15% of original size and saved as JPG (90% compression) using FastStone Image Viewer.
The images are somewhat degraded due to JPG compression and the constraints of the forum's file size limit. A difference can clearly be seen with the PNGs. Even the 50 & 100 stacks look different, the 100 clearly having more stars. Full size 100 stack here https://www.astrobin.com/412451/0/ .
The reader can make up their own mind and maybe go on and conduct their own investigation.
[Note: the single frame was loaded into PIPP; had the Siril generated master dark & master flat applied, debayered, saved as a FITS frame and post processed in Siril.]
Single frame
2 frame stack
5 frame stack
10 frame stack
25 frame stack
50 frame stack
100 frame stack
1 frame versus 100 frames
Dave
The images are somewhat degraded due to JPG compression and the constraints of the forum's file size limit. A difference can clearly be seen with the PNGs. Even the 50 & 100 stacks look different, the 100 clearly having more stars. Full size 100 stack here https://www.astrobin.com/412451/0/ .
The reader can make up their own mind and maybe go on and conduct their own investigation.
[Note: the single frame was loaded into PIPP; had the Siril generated master dark & master flat applied, debayered, saved as a FITS frame and post processed in Siril.]
Single frame
2 frame stack
5 frame stack
10 frame stack
25 frame stack
50 frame stack
100 frame stack
1 frame versus 100 frames
Dave