Author Topic: Dynamic Range and Local Contrast  (Read 12714 times)

Offline vicent_peris

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Dynamic Range and Local Contrast
« on: 2011 September 16 08:36:04 »
Hi all,

I've just published a tutorial about processing techniques concerning dynamic range and local contrast. Although it's an advanced tutorial, I think some sections can be easily followed. In this article I describe some techniques that are extremely important for me at this moment. I recommend to take a closer look to the star dynamic range compression section that speaks about the techniques I am using now to restore the Gaussian profile of the stars. Follow the below link to read the article:

http://pixinsight.com/tutorials/NGC7023-HDR/en.html


Hope you like it!
Best regards,
Vicent.

Offline Sean

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Re: Dynamic Range and Local Contrast
« Reply #1 on: 2011 September 17 11:48:49 »
Vicent,

Thank you for all the work you put into this tutorial. It describes several new techniques for me, and I'm sure that I will find them valuable in the future. I plan to rework one of my old images while following along, to better understand the processes involved.

Thanks again,

Sean

Offline Alejandro Tombolini

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Re: Dynamic Range and Local Contrast
« Reply #2 on: 2011 September 17 16:23:13 »
Hola Vincent, excelente tutorial, muchas gracias.

Tratando de seguirlo noté que mi MaskedStreth tiene 0,2 como valor máximo para Target median (es la misma versión), ¿hay alguna actualización del script?

Saludos. Alejandro.



Hi Vincent, great toturial, many thanks for it.

Trying to follow it I notice that my MaskedStretch has 0.2 as maximun value for Target median (same version), are there any update of the script?

Regards, Alejandro.

Offline Juan Conejero

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Re: Dynamic Range and Local Contrast
« Reply #3 on: 2011 September 18 12:37:31 »
Hi Alejandro,

You're right, the tutorial uses a customized version of the script. Do the following:

- Open the Process Explorer window

- Expand the Scripts > Utilities node

- Right-click the MaskedStretch script item and select "Edit Script"

- On the script editor, go to line number 508. This line has the following text:

        setRange (0.001, 0.2);

Replace it with

        setRange (0.001, 0.5);

Now save the modified script to any location and run it by pressing F9.

Let me know if this works.
Juan Conejero
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Offline Alejandro Tombolini

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Re: Dynamic Range and Local Contrast
« Reply #4 on: 2011 September 18 20:21:39 »
Yes, it worked perfectly! Thank you.

Saludos.
Alejandro.

Offline Giorgio

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Re: Dynamic Range and Local Contrast
« Reply #5 on: 2011 September 19 00:17:16 »
Hello I have this type of error
Why?

Offline Juan Conejero

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Re: Dynamic Range and Local Contrast
« Reply #6 on: 2011 September 19 02:02:32 »
Hi Giorgio,

Because the script is on a subfolder of "C:/Program Files", which is a system folder where you need administrative privileges to write a file.

For now, the solution is writing the modified script to a different folder where you have full access, such as your Documents folder for example, or your Desktop folder.

Later I'll release an update with the modified script for all platforms. Sorry for the inconvenience.
Juan Conejero
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Offline h0ughy

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Re: Dynamic Range and Local Contrast
« Reply #7 on: 2011 September 24 17:43:25 »
Hi all,

I've just published a tutorial about processing techniques concerning dynamic range and local contrast. Although it's an advanced tutorial, I think some sections can be easily followed. In this article I describe some techniques that are extremely important for me at this moment. I recommend to take a closer look to the star dynamic range compression section that speaks about the techniques I am using now to restore the Gaussian profile of the stars. Follow the below link to read the article:

http://pixinsight.com/tutorials/NGC7023-HDR/en.html


Hope you like it!
Best regards,
Vicent.

great article and hints but i cant get the mouseovers to work Vicent?
Doghouse Observatory

Offline cfranks

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Re: Dynamic Range and Local Contrast
« Reply #8 on: 2011 September 25 04:46:09 »
H0ughy,

I clicked on each of the mouse-over links and waited 'til they downloaded.  Then the MO works but the changes might be very subtle.

Charles

Offline Jordi Gallego

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Re: Dynamic Range and Local Contrast
« Reply #9 on: 2011 October 02 01:51:41 »
Very interesting turorial Vicent, thanks for sharing  :D
Jordi Gallego
www.astrophoto.es

Offline Harry page

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Re: Dynamic Range and Local Contrast
« Reply #10 on: 2011 October 05 12:39:29 »
Hi

How do you work out the median , mine says 2.2--   in the statistics bit  ::)

Regards Harry
Harry Page

Offline vicent_peris

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Re: Dynamic Range and Local Contrast
« Reply #11 on: 2011 October 05 14:08:47 »
Hi,

Thank you very much for your comments.

How do you work out the median , mine says 2.2--   in the statistics bit  ::)

I'm sorry, Harry, but I don't understand you...


Best regards,
Vicent.

Offline Harry page

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Re: Dynamic Range and Local Contrast
« Reply #12 on: 2011 October 05 14:22:01 »
Hi

Don't worry not many people can  >:D

How did you arrive and find the target median ?  ( 0.43 you used )

Regards Harry

Hi,

Thank you very much for your comments.

How do you work out the median , mine says 2.2--   in the statistics bit  ::)

I'm sorry, Harry, but I don't understand you...


Best regards,
Vicent.
Harry Page

Offline vicent_peris

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Re: Dynamic Range and Local Contrast
« Reply #13 on: 2011 October 06 14:28:31 »

How did you arrive and find the target median ?  ( 0.43 you used )


The goal is to make a similar stretching with MST as the one you have with the histogram-stretched image (this doesn't need to be very precise). Simply read the statistics of the latter image and put this value in the target median parameter of MST.


Regards,
Vicent.

Offline Harry page

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Re: Dynamic Range and Local Contrast
« Reply #14 on: 2011 October 07 11:18:39 »
Hi

Vincent

I have used your star technique , and it works really well  :D

http://www.harrysastroshed.com/Image%20html/zoommcocoon2011/cocoonjpeg2011/cocoon20113.html

Many thanks for your work

Harry
Harry Page