Pixinsight - HDR Compositions - What am I doing wrong?

[AstroJOE]

I'm still very much a beginner with Pixinsight, having recently downloaded the 45 day trial version. I've spent some time watching Harry's videos which were very useful so I've got a fair idea of how to do the basics now. Lots more practice needed though!

I'm now trying to combine 2 different exposures of M42...one stack of 600s and one stack of 30s......both previously stacked in DSS. I've tried doing a Star Alignment and then an HDR Composition, but the resulting image leaves me with stars that I can only really describe as looking like diamond rings. To be honest I'm not entirely sure I'm doing either of these processes correctly but I'm struggling to find any material on how to do it right. The HDR image also looks, well bad.

I've attached some images showing the before and after....obviously I'm going wrong somewhere but can't figure out what........

Anyone able to assist?

 

M42 600 Outer.TIF

M42 30 Inner.TIF

M42 - HDR.fit

[AstroJOE]

Try this, here's the resulting HDR Composition image

What process should I be following to combine these 2 different stacked exposures?

[MARS1960]

I needed this answered once.

Goto light vortex astronomy website and find HDR composition tutorial, it tells you exactly how to do what you are wanting to do.

[wimvb]

Also have a look here:

https://pixinsight.com/forum/index.php?topic=4849.0

and to learn from a master:

http://www.deepskycolors.com/archivo/2011/01/19/hdr-Composition-with-Pixinsight.html

One thing I noticed from your images is that even the shorter exposure seems to have an overexposed core. Are your images linear??

[AstroJOE]

Thanks for the replies I shall have another go later. 

 

3 hours ago, wimvb said:

Also have a look here:

https://pixinsight.com/forum/index.php?topic=4849.0

and to learn from a master:

http://www.deepskycolors.com/archivo/2011/01/19/hdr-Composition-with-Pixinsight.html

One thing I noticed from your images is that even the shorter exposure seems to have an overexposed core. Are your images linear??

Yes both the images are linear, well the only processing on both was a RGB alignment and slight saturation increase in DSS after stacking, prior to saving. I see what you mean though. I did take some 5s exposures to capture the Trapezium which I can add later, once I've mastered the HDR bit with these 2 sets. 

 

[MARS1960]

If you try with Wim's second link i think HDRWT has been replaced with HDRMT, just incase you spend ages trying to find it .

Your HDRC image is good, i think it is just lacking in longer exposure subs being added to bring out the faint detail that is obviously there, this will help balance the image but that core does need attention. If you look at my 2 images even with the 30s subs i added to bring the core down and balance the image i still couldn't keep the core under control, even with my basic knowledge of PI. 

I think the key to this for me is learning how to properly use masks, and, if someone can tell me how in gods name do i get my head around pixelmath i would be a very happy chappy .

 

 

[wimvb]

Thanks for the process/link update, Mark

As for pixelmath, do you know about this:

http://www.werbeagentur.org/oldwexi/PixInsight/PixInsight.html ?

Also, David Ault seems to have pixelmath tutorials on his site. Haven't checked them out yet.

http://trappedphotons.com/blog/

[steviemac500]

What do your unprocessed calibrated frames look like? I had a very similar issue recently with my stars. I solved it by increasing the sigma in the light frames - low value to nearly max and high value to really low. 

[AstroJOE]

3 hours ago, steviemac500 said:

What do your unprocessed calibrated frames look like? I had a very similar issue recently with my stars. I solved it by increasing the sigma in the light frames - low value to nearly max and high value to really low. 

I've included a link to the unprocessed calibrated frames in my original post (one is a 600s stack and the other is 60s stack. The stars look fine in them, albeit the brightest ones are a bit saturated. But the strange hollowed out effect in the HDR image seems to be on every star across the whole image.