Show Posts

This section allows you to view all posts made by this member. Note that you can only see posts made in areas you currently have access to.

Messages - drmikevt

Pages: 1 ... 3 4 [5] 6 7 8
Gallery / Re: HOO Crescent in an SHO field
« on: 2017 September 11 19:00:58 »
A complete re-processing.  A better result? 

Gallery / Re: HOO Crescent in an SHO field
« on: 2017 September 09 09:02:48 »
A bit of a color correction:

Gallery / HOO Crescent in an SHO field
« on: 2017 September 08 21:54:07 »
I wanted an SHO image of the Crescent area, but I like how an HOO rendering gives much better contrast between the Ha 'ribs' and the O3 shell. After combining in SHO, I masked off the Crescent and changed it to HOO, then applied a custom SHO blend to the whole image, which served to blend the SHO and HOO areas, and proceeded with a normal workflow from there. I'm sure there are many revisions to come, but for now I like the achieved result.  It might be a little blue, other versions have been more green...   Criticism and areas to improve are welcome.  The new LN process was used, which really helped my less than perfect data. 

Capture:  SV80ST, QSI683wsg-8, Paramount MyT
40x900s each S, H, O (30hours total)
Larger version:


General / Re: Superbias with Partial Bad Columns
« on: 2017 August 15 18:53:00 »
I discussed this exact topic with Vincent not too long ago and, while I certainly can not speak for him, what I had gleaned from the conversation was that Superbias can not handle chips with partial column defects (I used to have a chip with one and he showed me how it was introducing artifacts compared to a stacked bias).  Apparently, the process was originally intended for CMOS cameras which handle columns differently.  His recommendation was not to use it with CCD's, but if you don't have a partial column issue I think it can work well. 

Again, this is my understanding of what was said.


General / Re: My Basic Calibration Routine
« on: 2017 August 09 14:45:41 »
Yes, there are equations, but who cares if you like what you see? And I get your point about sky flats. 

I should point out that (although not to you, but to folks in general who might read this) that the '22-24 is optimal' thing only applies to calibration frames where building signal is not the goal.  It is the point at which, from a pure noise perspective, there is little to gained by going further - not nothing, but little.  Bias is the exception because there you are trying to build a characterization of the base signal of the chip.   - at least, that's how I currently understand things to be.


General / Re: My Basic Calibration Routine
« on: 2017 August 09 12:58:49 »
2 things:
 - Why so few flats?  Various people have debated how many calibration frames are needed and math tells us that the critical number in terms of noise vs wanting-to-take-as-frames-as possible is 22-24.  Lots of people just take 50 flats as a norm.  I think, with just 16, your flats would be adding noise unnecessarily (because they are noisy themselves).  Also - are you stacking your E and W flats together?  It is unclear from your description above.  If you rotate your camera than you can't do that.  If you don't rotate the camera on the flip then its fine, and it doesn't matter (or shouldn't) whether you take them on the E or W. 

 - SuperBias is not really meant for CCD chips.  It was designed for CMOS chips which behave differently.  If you have any partial column defects on your CCD, super bias will not handle this correctly and you will introduce error.  If your CCD is very clean, then you can use it if you want.  Personally I take 300 and the stack looks pretty nice.

That's all I got

General / Re: reducing star sizes
« on: 2017 August 09 05:50:44 »
Yes, once the stars are clipped you can not recover color information.   

Try this:
 - Prepare your RGB and L frames as you like
 - Just before LRGB combine, run HDRMultiscaleTransform on both images (set to 6 or 7 or 8 layers)
 - Comine LRGB as normal

Are you stars better? 


Thank you, Juan!  You are always so quick to fix these things.  Much appreciated!


I can also confirm this issue with Pixelmath - it just crashed the program... and I lost my entire project.... :(
Mac, El Capitan 10.11.6, Macbook Pro 2012 (non-retina)

For me, I got a similar error message as above a few times and then it just crashed. It always seemed to happen when exiting the Expressions editor. 


A lot of people will apply a heavy HDRMT before running star mask - it really helps to separate the stars from the nebula. 

General / Re: Mixed SHO/HOO image - need help from the masters
« on: 2017 August 04 17:31:43 »

I solved it in another way.  I realized I was doing 2 things wrong:
 - Things were much better behaved after I linear fit the 3 NB images before combining them.
 - I was trying to manipulate the data before color calibration.  Everything worked much bette after using the new PCC tool. 
 - After PCC, I applied the expression
R:  $T[1]
G:  $T[2]
B:  $T[2]
to the SHO image through a mask revealing only the Crescent.  I'm really happy with the attached result.  My goal was to bring out more detail in the wrapper nebula, and it does that.  The attached image is so squashed that you can't see it nearly as well as a full size (of course), but you should be able to see the effect.  I need to go back now and process it properly to see what I can tease out of it.  The attached image is just Channel Combine to SHO, PCC, masked Pixelmath, SCNR, HT, and Curves.  Enjoy and thank you for your help!

If you want I can still post the other files, but as you can see the HOO image is not necessary.


General / Re: Mixed SHO/HOO image - need help from the masters
« on: 2017 August 04 10:33:02 »
Well, it sort of works.  I tried it a bunch of different ways:
 - Your way, above
 - Using H, O, O as RGB in PM and inserting
 - using the expression $T[1] for R and $T[2] for G, B (to re-asign the existing SHO data)

They all produce different, but similar results.  Some look better, but none look 'normal'.  When I apply your method I get the result below.  I get the exact same result if I put your equation into all the channels and apply it.  Just FYI - you can apply PM through a mask - same result.  It is curious that the crescent image looks nothing like a straight HOO combine in channel combination.  There must be some interacting between the 2 images instead of a simple inserting of the new data.  I'm not sure where to go!  It would also be great if part of the expression was able to detect and ignore the background and only replace the higher pixel values - I know this is possible, I just don't know how to do it.


General / PCC calibrates SHO, but not HOO..?
« on: 2017 August 04 08:18:13 »
I'm trying to figure this out:  the new PCC process will calibrate an SHO image just fine, but fails on the HOO image of the same data.  I keep getting "insufficient photometric data, need 5 image, got 0".  I've tried decreasing the sensitivity but that doesn't seem to help.   It does solve the image and then goes through the steps of the process, but fails at the end.  It tell me that '3 of 3 images processed successfully with 0 images with errors'.  The results with the SHO image are so, so nice that I want to see what it does with HOO. 

Any ideas?

Announcements / Re: PixInsight 1.8.5 Released
« on: 2017 August 03 10:53:56 »
Thank you!!!!  Your efforts, and those of the team, are sincerely appreciated. 


General / Mixed SHO/HOO image - need help from the masters
« on: 2017 August 03 08:07:58 »
I just finished collected the attached data for the Crescent and related nebula.  The image is a straight SHO combine with no processing at all other than color calibration and stretching.  I really like the data and the rich nebula field, and plan to process that properly in SHO, but I also really like the look of an HOO crescent to better bring out the Ha 'skeleton' and O3 'bubble wrap'. 

I would love some advice on how to best create an image where the nebula is SHO and the crescent itself is HOO.  Any and all ideas and advice will be greatly appreciated. 

Thank you!

Pages: 1 ... 3 4 [5] 6 7 8