Author Topic: color cast in background  (Read 444 times)

Offline bcstein12

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color cast in background
« on: 2018 February 21 22:01:45 »
I'm trying to produce a HDR image of M31 but a keep getting a strong color cast in the background.  I have taken 30,60,180 and 600sec RGB subs and did DBE on each master before I combined with HDR.  I then used channel combination to combine but end up with a strong "color cast" to the corners.  I ran dbe several times on each of the masters.  cast was still visable after using photometric color calibration.  I tried channel combination on the 180 and 600 sec masters seperately and noticed the cast was not on the 180 RGB but on the 600 RGB.  SO what gives and would I be able to fix the background before or after stretching if i use the 600sec masters

Offline bcstein12

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Re: color cast in background
« Reply #1 on: 2018 February 21 22:05:28 »
here is enlargement

Offline Greg Schwimer

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Re: color cast in background
« Reply #2 on: 2018 February 21 22:13:21 »
Thinking about how HDRComposition works, it makes sense to me that the 600s subs would contribute the background and the cast to the image. I would try running HDRComp with aligned but otherwise untouched masters first. Crop as you wish from there, then run DBE.

A good trick for seeing the cast while placing your sample points is to use a boosted STF stretch.
- Greg
Scottsdale, Arizona, USA

Offline bcstein12

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Re: color cast in background
« Reply #3 on: 2018 February 22 06:46:33 »
the cast was produced just combining the 600sec masters only before using hdr as compared with no cast using the 180sec masters