Banana-scope Rosette reprocessed

[MarkS]

I've just tried a different processing sequence which has produced tighter stars and sharper detail - drizzle.  So instead of a normal stack I've used drizzle stack (within IRIS of course!) to create a drizzled image of twice the size and then used 2x2 binning to reduce it back.  Note that I deliberately used dithering when shooting the subs in order to allow this later drizzle processing. See what you think:

Original stack:


Drizzled stack:


And here are the full-size versions:
Original:  http://www.markshelley.co.uk/webdisk/tak_rosette14032010.jpg  
Drizzled:  http://www.markshelley.co.uk/webdisk/rosettedrizzle.jpg

Clearly I need much more data to reduce the noise.  But don't forget this has been taken with a DSLR - so only one quarter of the pixels are responsive to the H-alpha.

I think drizzling may become my processing sequence of choice.  In fact, I now want to revist some of my earlier images!

Mark

[mickw]

I prefer the first one, seems better contrast

[JohnP]

Have to say mark my vote is with first as well. The effect of doing the drizzle looks almost the same as doing an unsharp mask on stars only - it has made them sharper & much brighter (which has bought out a lot more stars in the background) but perhaps too bright they almost looked clipped. The first for me looks more natural...

John

[Rick]

Hmmm... The second one does seem to show more detail in the nebulosity, but the stars in it have a slightly bloated look when compared with the first image...

[MarkS]

I'll give this another go and make sure that I apply exactly the same steps to each image (apart from the drizzling of course) - it will then be a fairer test.

I don't think I applied the same arcsine range scaling on the drizzled image - which is why the stars look brighter and clipped.

Mark

[Carole]

Hmmm... The second one does seem to show more detail in the nebulosity, but the stars in it have a slightly bloated look when compared with the first image...

Yes this was my impression. I prefer some elements of the 2nd one, and some from the first!!

Carole

[RobertM]

I agree with Rick but even so it's not bad for a DSLR 

If you don't mind I'd like to try it with my FLI camera and Ha filter wheel sometime, I have the canon adaptor so it should just be a matter of fitting it to the bayonet on the camera adaptor (and hoping for no flex !).

[Fay]

I prefer the first one too Mark, second one does look like a slightly over sharpened image.