By accident I shot various images of SH2-112 and SH2-115:
Both nebulae: | SH2-112 only | SH2-115 only |
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I was wondering about ways to combine these:
- Treating them as a mosaic, i.e. preprocess separately and then combine (using Average - not Overlay in GradientMergeMosaic!!!)
- Preprocessing them combined
The first one was fairly straight-forward. I preprocessed them as I always do and then used the
GradientMergeMosaic process in Pixinsight.
For the second one, I did the following:
- weighted them together
- calibrated them separately
- registered them to one of the images that has both nebulae
- stacked them together
Here is the outcome of both processes:
Mosaic | Preprocessed combined |
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Well, that's pretty clear ...
But I still wanted to find out if the stacking of all images improved the quality of the image. So, I cut out SH2-115 from both images and compared those:
SH2-15 in mosaic | SH2-115 in combined image |
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Interestingly enough, the mosaic image seems to have a slightly higher SNR. So, I'll go with that method.