Pacman Nebula Constructive Critique Requested · Paul O’Brien · ... · 13 · 126 · 4

Vivian Budnik:
Hello Paul,
I love the color composition, and in general this is nice work. The only criticism I would have is that the stars are surrounded by dark halos. This is particularly noticeable in the stars overlapping the nebula, but I can see this in other stars as well. Did you do any kind of star redaction/substitution? The halos seem to be more pronounced in small stars. My guess is that when you do star reduction/substitution, you should make different masks for different star sizes. This can be accomplished by using morphological transformation using the "close" option. This would allow you to have different masks for several star sizes (e.g. large, medium, small, very small). Then you can refine your masks for each group of stars with morphological transformation dilation or erosion, until the mask is fairly similar to the star mask.

The problem when making star masks, by any method is that different star sizes are not similarly covered by the mask. For the large stars the mask might be too small, while for the smaller stars, the mask might be too large (in this latter case resulting in the presence of halos when substituting) You can solve this by using different masks depending on star size. I hope this helps
Clear skies,

Vivian

Uwe Deutermann:
Can only agree with Vivian above, the star handling suffered from reduction done too harsh. Color assignments look very good! I do not like the dark area inside Pacman either, not sure what was done to make it look like that, looks too blotchy if you ask me. Overdone noise reduction maybe?

The red parts outside of the Pacman is indeed Hα, and that you caught this is really good!

All in all, a nice image, I think if you get the star and ark area handling under control it will be a wall hanger 😊

Thanks, Vivian, and I agree.  I did not use star reduction.  I believe part of the problem was that I screwed up my decon process.  At that time, I was kind of lost in correctly applying this tool.  Your tips in creating different star masks using morphological transformation is much appreciated.   I'm probably doing something wrong with MT but I seem to get weird core artifacts when processing galaxies so I've shied away from it recently.  I also have started using StarXTerminator, which I've found very useful.  I'll definitely try your suggestions.   Live and learn!

Uwe Deutermann:
Just read you response to Vivian, and yes, now this makes sense, the Deconvolution does do that, had it many times, and sometimes I cannot find any setting to avoid it. 

I meant this dark area: 


I compare that with one of my images (easiest to do ... there are much better ones out there though) and it looks like this: 


I hope you see what I mean. I also see that the images are horizontally mirrored, hmmm ... I wonder now who of us did the flip 😉.

Hope that helps as explanation!

Paul O’Brien:

John Favalessa:

Thanks, Vivian, and I agree.  I did not use star reduction.  I believe part of the problem was that I screwed up my decon process.  At that time, I was kind of lost in correctly applying this tool.  Your tips in creating different star masks using morphological transformation is much appreciated.   I'm probably doing something wrong with MT but I seem to get weird core artifacts when processing galaxies so I've shied away from it recently.  I also have started using StarXTerminator, which I've found very useful.  I'll definitely try your suggestions.   Live and learn!

Decon can certainly mess up stars.  Decon is also difficult to get right.  There is a good youtube video by Adam Block on using it, but also there is a script "EZ Processing Suite" which does a fairly good job out of the box.  It's an add-in to Pix.  https://darkarchon.internet-box.ch:8443  After adding the URL to "Manage Repositories", do an update.  Once you do this you should see the Suite under the main menu, Script.  It also has some other good scripts in it.

John Favalessa:

Thanks, Vivian, and I agree.  I did not use star reduction.  I believe part of the problem was that I screwed up my decon process.  At that time, I was kind of lost in correctly applying this tool.  Your tips in creating different star masks using morphological transformation is much appreciated.   I'm probably doing something wrong with MT but I seem to get weird core artifacts when processing galaxies so I've shied away from it recently.  I also have started using StarXTerminator, which I've found very useful.  I'll definitely try your suggestions.   Live and learn!

Decon can certainly mess up stars.  Decon is also difficult to get right.  There is a good youtube video by Adam Block on using it, but also there is a script "EZ Processing Suite" which does a fairly good job out of the box.  It's an add-in to Pix.  https://darkarchon.internet-box.ch:8443  After adding the URL to "Manage Repositories", do an update.  Once you do this you should see the Suite under the main menu, Script.  It also has some other good scripts in it.

Thanks, John.  Yes, after doing my first couple of images, I downloaded the "EZ Processing Suite" and used it a few times.   It's worked on several projects and not so good on one or two others, in which I've gone back to doing it manually through Decon.  I've also recently started using Herbert Walter's scripts and used a number of them too.  Love GAME, AdvSharpen, MaskGen, PSFImage, etc.  Very cool.  Keep those comments coming! OH