Overscan setting results in diagonal stripes in calibrated Lights QHY168

[rockenrog]

Hi,
I have been looking for clear information on the actual writing of the Overscan pixel coordinate settings in ImageCalibration. But no, cannot find.
Please look at attached pixel coordinates from a raw flat frame with overscan not removed at the QHY168C camera.

What numbers should I be be putting in the Overscan dialogue boxes? Someone must know!

Thanks,
   Roger

[bulrichl]

Hi Roger,

As far as I know there is no real Overscan region in cameras with a CMOS sensor, only some advanced CCD sensors have this feature. The "optically black" regions of some CMOS sensors (e.g. in Canon DSLRs and a few Sony sensors) is different and cannot be used for calibration by the user. It seems that in CMOS cameras the optically black region IS already evaluated by the camera electronics.

The QHY168 utilizes a Sony IMX071 sensor. I am not aware that Sony published any details about the optically black regions. The only publication about this topic that I know is https://landingfield.wordpress.com/2014/06/07/imx071-characteristics-2/ . Of course you can ask QHY why they make the optically black region accessible to the user and what to do with it.

Even if the optically black region was useful for Overscan calibration your input to the ImageCalibration/Overscan section would be wrong: as explained by mouse-over texts, the input fields expect values of:

Code: [Select]

left pixel coordinate | top pixel coordinate | width in pixels | height in pixels
(the last two input fields don't expect coordinates but width and height of the corresponding region).

Bernd

[rockenrog]

Hi Bernd,
Thank you for your help. The QHY168C does have overscan areas, and the file I posted shows the coordinates of the 3 overscan areas and the image areas.
The mouse-overs do help, but I still cannot determine the correct source and target numbers. Just getting PI to process does not mean the overscan data put in is correct.

So I am still looking for someone to show the correct Overscan data points for the file I uploaded.

Thanks,
    Roger

[dave_galera]

Roger, does this help at all?

https://pixinsight.com/forum/index.php?topic=12950.0

[bulrichl]

Roger, does this help at all?

https://pixinsight.com/forum/index.php?topic=12950.0

Probably not.

The following links could be helpful you:

https://pixinsight.com/forum/index.php?topic=10900   and the websites cited in post #8
www.iceinspace.com.au/forum/showthread.php?t=112592

Bernd

[rockenrog]

Hi Bernd,
Thank you for your efforts to find some other posts regarding this overscan. I had read these and from the latter one I learned that just because it will run, does not mean it is correct. Thus I started this post.
Now I am going to approach the problem a different way with a new post with at technical article. I hope someone with the knowledge to fully understand this can point me to the right direction.
It will be called Dark Frame Calibration.

Thanks,
    Roger