Unusual (to me) behaviour with Drizzle and LocalNormalization

[ramdom]

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/ou4_sh2-129_Ha_nf.v0_d.resized.jpg

Drizzle with LocalNormalization: http://ram.org/images/space/downloads/ou4_sh2-129_Ha_nf.v0_l_d.resized.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

 

[Davey-T]

AKAIK images to be drizzled should be dithered and under sampled.

Dave

[ramdom]

Thanks Dave - yeah, that's the case here but I'm actually integrating data from two resolutions and both are undersampled but one more so than the other.  So it shouldn't be occurring IMO.  But I will investigate further to make sure the same histogram is being applied.

--Ram