Unusual (to me) behaviour with Drizzle and LocalNormalization

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ram United States of America
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Unusual (to me) behaviour with Drizzle and LocalNormalization

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Post by ram »


Hi all, I'm puzzled by this behaviour of Drizzle and LocalNormalization. Here are the two images I'm referring to - after Integration, only an AutoSTF has been applied to make the image:

Drizzle only: http://ram.org/images/space/downloads/o ... esized.jpg

Drizzle with LocalNormalization: http://ram.org/images/space/downloads/o ... esized.jpg

I've never seen this behaviour before and I've experimented a lot with both these algorithms. The Drizzle data is actually a bit soft (which I've never seen happen - almost always it improves things) and appears to be missing/details/decreased. LocalNormalization for the first time actually brings out details/improves things in a noticeable manner - usually I find it helps even out gradients a bit but it's never as extreme as this.

Does anyone know if this is fine (I'm actually quite happy with the LN image) or if I'm doing something wrong and if there are other things like this that I'm missing that could influence the signal levels. I'm using the default parametres for both Drizzle and LN (and for most other steps - I'm using GESD Test for ImageIntegration).

Thanks a lot!

--Ram
Tubes: Celestron 9.25" 235mm f/10 XLT EdgeHD SCT; Meade ETX 80mm f/5 achromat; Coronado SolarMax II 60mm f/6.6 Hα <0.7Å BF10 solar; Stellarvue 70mm f/6 triplet apochromat; Obsession UC18 457mm f/4.2 with Argo Navis & ServoCAT; Takahashi FS128 5" f/8.1 and FC100DF 4" f/7.4 fluorite doublet apochromats. Mounts: AVX; LXD75; Paramount MyT. Eyepieces: 2" Tele Vue Ethos 4.7/13/21mm, Paracorr, 2,4x Powermate; Stellarvue 0.8x, Takahashi 0.7x, 0.66x reducer/corrector. Cameras: ZWO ASI120MC-S; Lodestar X2c; X2m; Canon T7i; QHY163M; QHY247C; QHY294M-Pro. Filters: 1.25" Astrodon 5nm Ha, 3nm O3 and S2; Chroma LRGB.
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