Combining dark frames with different black points

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ColinR
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Joined: Fri Oct 12, 2018 1:20 pm

Combining dark frames with different black points

#1

Post by ColinR »

I have two sets of dark frames both at 180s Gain300. However one has a Black Point of zero and the other a BP of 10. Can I combine these into one larger file for my Dark library?

Colin
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Re: Combining dark frames with different black points

#2

Post by admin »

Hi,

In theory it could be done (not using SharpCap, but using other software). You could find some processing software that will allow you to adjust the black point of one of the sets of dark frames to match the black point of the other and then merge them together into a master dark. I know that pixinsight could manage this, but obviously that costs $$$$. I'm sure there are other tools that have the same ability that are freeware, but I can't think of any that I know will do this for sure. You'd need to be very careful to make sure that you got everything perfectly right otherwise you could end up making a master dark frame that won't subtract well. You would also need to make sure that the light frames that you later capture use the same black point as your composite master dark frame to ensure correct subtraction.

Hope this helps, Robin
ColinR
Posts: 37
Joined: Fri Oct 12, 2018 1:20 pm

Re: Combining dark frames with different black points

#3

Post by ColinR »

Hi Robin,

Thanks for your reply. I will look at my Pixinsight and see how this could be done. Otherwise, when adding to my dark files library I will record the Black Point as well as the other exposure and temperature data.

Thanks again.

Colin

PS Making good use of Smart Histogram and Brain, (I hope!).
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