Dark capture with PNG
Posted: Sat Oct 10, 2026 10:28 pm
Hello Robin,
I'm doing some "library" of dark with my QHY miniCam8 camera.
The camera was first in Live View mode and I did the dark capture up to 60s.
But for 120s, I changed to Still mode. I did not remark that SharpCap changed the output format from FITS to PNG.
Are the PNG image in SharpCap full equivalent to the FITS image ?
I ask while the FITS does not have "unsigned" type and the image is first scaled (shift).
But, that is not the topic ... I remark an image shift between the FITS and the PNG. Both images have a size of 3856x2180 pixels.
When I reopen the FITS (60s) and the PNG (120s), a small shift of the hot pixels is visible on the image.
I was first looking at the middle of the image, so I though that it was the up-down read direction. But it is not, when I look at the top-left corner.
Here both images reopened in SharpCap:
Note the capture was done with last 4.2 beta. I reopened the image with 4.1.
Regards,
Jean-Francois
I'm doing some "library" of dark with my QHY miniCam8 camera.
The camera was first in Live View mode and I did the dark capture up to 60s.
But for 120s, I changed to Still mode. I did not remark that SharpCap changed the output format from FITS to PNG.
Are the PNG image in SharpCap full equivalent to the FITS image ?
I ask while the FITS does not have "unsigned" type and the image is first scaled (shift).
But, that is not the topic ... I remark an image shift between the FITS and the PNG. Both images have a size of 3856x2180 pixels.
When I reopen the FITS (60s) and the PNG (120s), a small shift of the hot pixels is visible on the image.
I was first looking at the middle of the image, so I though that it was the up-down read direction. But it is not, when I look at the top-left corner.
Here both images reopened in SharpCap:
- Capture_Dark_FITS-PNG_1.jpg (278.24 KiB) Viewed 59 times
- Capture_Dark_FITS-PNG_2.jpg (302.99 KiB) Viewed 59 times
Note the capture was done with last 4.2 beta. I reopened the image with 4.1.
Regards,
Jean-Francois