M31 and HDRWavelets

[Nocturnal]

Hi,

I'm trying to apply the M101 tutorial http://pixinsight.com/examples/HDRWT/M101/en.html to an M31 image I took a while back. I'm not having much luck. The core keeps getting a ring around it. I used DBE to remove sky gradient due to the moon being present at the time (I know, not the best time to image).

Should I add a mask to the image and first process the core and other bright areas and then the dimmer ones by reversing the mask? Try a different process for getting some detail out of the core instead? Perhaps M31s core is more evenly illuminated than I thought. This is where the profile tool I asked for earlier would come in handy

I've uploaded a crop of the image in its current processing state. No stretches have been performed, just crops and DBE.

http://cid-a93625fef5ca95fb.skydrive.live.com/self.aspx/PixInsight/M31-crop.7z

Thanks for any insight you can provide!

I'll keep playing with this and maybe add some screenshots to show the effects I'm seeing.

[andyschlei]

Sander,

I can't seem to access the image from the link you've provided.

--Andy

[Nocturnal]

Hi Andy,

I just clicked on the link and it's there. It shows it's accessible to anyone. What's the problem you are experiencing?

[andyschlei]

I reports that it is a "7z" file.

What's the format?  FITS?

[Nocturnal]

http://www.7-zip.org

An open source compressor. Whips FITS smaller than anything else I've tried.

[andyschlei]

http://www.7-zip.org

An open source compressor. Whips FITS smaller than anything else I've tried.

Aaah.  I see.

That's a good thing to know -- zip doesn't do enough to make it worth using.

[andyschlei]

Sander,

I took a stab at your image.

I converted to 32 bit integer
Rescaled
Stretched to visibility with histogram
Applied 2 iterations of HDR wavelet (4 was too many, 1 would have been OK too)
Stretched in curves to brighten
Stretched colors a bit in histogram.

Here is my result



A process container with all details as specified above is at this link

M31-Process.psm

HTH

--Andy

[Nocturnal]

Hi Andy,

well that looks very promising! Thanks very much for doing this. I have since taken new M31 exposures so I will try your suggestion on that and let you know how it worked out.