76 replies to this topic

[LauraMS]

Hi Rolf,

Re flat frame I very well know the situation without flats - sometimes I forget them, or for one reason or the other they are not useful :-)

I completely understand that dust is not easy to get ignored - maybe it can be detected by means of the fact that it does not move at all while - at least at the resolution I use - most 'real' details move or are at least 'warped'. And dust usually is significantly larger than one pixel, but not very large. Just some ideas which come to my mind but maybe you have better ideas. Or just implement flats ;-)

If you need solar data as a use case just let me know.

Best wishes,
Laura

Edited by LauraMS, 21 May 2019 - 05:12 AM.

[Rolf]

Hi Laura,

 

Thank you very much for sharing your ideas! I don't think it would be easy to detect dust by how it looks like. That would take way too much computing time (e.g. using machine learning techniques). Your other thought is much better, and very close to what I already had in mind. I measure shifts in two places: At the global scale during image stabilization, and then later when I measure the local warp at each AP. The nice thing is that I use two different mechanisms for the two phases. Since, as you wrote, the dust does not move on the sensor, at an AP which is dominated by a large dust speck, the warp shift exactly counteracts the global frame shift. And this is the same for all frames. It is VERY unlikely that such a coincidence is caused by seeing. Therefore, I only have to look for this pattern at all APs and elimnate those where this is the case. Should work very well, and (very important) not cause much computing overhead.

 

I will try this out soon. The next three days, however, I will be on business travel. So PSS has to wait for a while.

 

All the best,

 Rolf

 

PS: Thank you for offering solar test data. That will be very useful during the gradual improvement of the code. As soon as I have a new version, I will announce it in this forum.