PixInsight Forum (historical)

PixInsight => Wish List => Topic started by: Simon Hicks on 2008 January 10 05:57:22

Title: Star Graphing / FWHM Feature
Post by: Simon Hicks on 2008 January 10 05:57:22
Hi PI Guys,
                    Suggestion for a useful feature. It would be great to be able to drag a rectangle around a single star, or click on a star, and see a graph of intensity (better still...L,R,G and B) vs radial distribution in pixels. It could show FWHM or any other useful info. I think this might be helpful when analysing the various features in an image...useful to see if stars have saturated in one colour, and also useful for knowing what parameters to put into a deconvolution module.

By the way...I can sort of estimate FWHM at the moment....just zoom right in till I can see individual pixels, then move cursor around till I see half the max intensity (taking background into account) and then just counting pixels to the corresponding position on the other side of the star.  But how does the FWHM relate to the Standard Deviation that is used in the Deconvolution module? Is there a simple multiplier so I can estimate one from the other?

Regards
                Simon
Title: Star Graphing / FWHM Feature
Post by: Juan Conejero on 2008 January 10 06:09:34
Hi Simon

We have almost ready a new star statistics tool that works in a similar way to what you have described. It should be ready soon, and of course it will give FWHM measurements, among other values (centroid coordinates, peak value, total flux, etc).

The full width at half maximum (FWHM) of a Gaussian function is given by:



where sigma is the standard deviation of the Gaussian distribution. A sufficiently approximate formula is:



Cheers
Juan
Title: Star Graphing / FWHM Feature
Post by: Simon Hicks on 2008 January 10 12:28:27
Hi Juan,
               Fantastic...thanks again!  :D

Cheers
             Simon
Title: Star Graphing / FWHM Feature
Post by: Andres.Pozo on 2008 August 22 03:57:54
Juan, this tool would be great if it could also automatically find the stars in the image and show the average FWHM and perhaps other statistics. DeepSkyStacker has a measurement like this, but I don't know if I can trust it.

I think you are developing an automatic registration tool so using it for finding the stars the "star statistics tool" can be made quite easily.

However, in my opinion, PixInsight has other priorities (documentation of the algorithms, documentation of the user interface, saving of sessions, customizable toolbars, better support for dual screen, ...).
Title: Star Graphing / FWHM Feature
Post by: Nocturnal on 2008 August 26 21:54:30
I think the DSS FWHM feature works fine. DeepSkyStacker Live is great to monitor the image quality as the images come in.
Title: Star Graphing / FWHM Feature
Post by: Juan Conejero on 2008 August 27 12:43:56
Hi Andrés,

I add to Sander's opinion about the quality of DSS's FWHM measurements: you can definitely trust them.

Regarding a tool for star statistics in PixInsight, it is in the TODO list with a high priority level. It will be available, and quite soon, hopefully.

With respect to PixInsight's handling of dual-monitor setups, which are your complaints? I am very interested in knowing them because dual monitor support is an important feature of PI's GUI.
Title: Star Graphing / FWHM Feature
Post by: Andres.Pozo on 2008 August 27 13:44:51
Quote from: "Juan Conejero"

With respect to PixInsight's handling of dual-monitor setups, which are your complaints? I am very interested in knowing them because dual monitor support is an important feature of PI's GUI.


I use a couple of monitors of different resolution and one of them is on a portrait orientation. I don't know how to use the full area of both monitors. IMHO it would be better if you could place the property pages of the tools outside the window of PixInsight. In this way I could put them where I like.
Title: Re: Star Graphing / FWHM Feature
Post by: NKV on 2010 April 28 06:17:42
Quote from: Juan Conejero on 2008 January 10 06:09:34
We have almost ready a new star statistics tool that works in a similar way to what you have described. It should be ready soon, and of course it will give FWHM measurements, among other values (centroid coordinates, peak value, total flux, etc).
Juan,  ???
Title: Re: Star Graphing / FWHM Feature
Post by: RobF2 on 2010 May 26 02:21:13
Wow - had not heard of DSS Live - sounds like a very useful concept - must check out

+1 for these astrometric indicators to become available in PI too.....
Title: Re: Star Graphing / FWHM Feature
Post by: Carlos Milovic on 2010 May 26 08:26:17
We are very close. Take a look at the Software Development subforum. I have uploaded beta versions of our PSF reader tool.
Title: Re: Star Graphing / FWHM Feature
Post by: RobF2 on 2010 May 27 04:50:11
Thanks Carlos - I did start reading about your PSF reader work, but wasn't smart enough to figure out compiling etc.
I think the beta might have been 64bit only too from memory? (I'm running XP 32bit)
Title: Re: Star Graphing / FWHM Feature
Post by: Carlos Milovic on 2010 May 27 05:57:27
I'll upload this evening the win 32 compilation. ;)
Title: Re: Star Graphing / FWHM Feature
Post by: RobF2 on 2010 May 27 06:18:05
Quote from: Carlos Milovic on 2010 May 27 05:57:27
I'll upload this evening the win 32 compilation. ;)

Thanks Carlos!   :)   8)