New Processing Example: Processing a H-alpha CCD Image with PixInsight, by Daniel Bosch

[Juan Conejero]

There is a new processing example available on PixInsight's website:

Processing a H-alpha CCD Image with PixInsight, by Daniel Bosch
http://pixinsight.com/examples/intro/dbosch-ha/en.html

Daniel Bosch is an excellent astrophotographer from Banyoles, Girona, Spain, and a PixInsight Standard user. In this tutorial Daniel shows us how he has processed one of his latest works: an H-alpha image of the Gamma Cygni region, acquired with a STL11K CCD camera through a Takahashi FSQ106 ED refractor. Daniel explains the step-by-step implementation in PixInsight of a simple procedure that has allowed him to achieve excellent results.

This is an entry-level processing example accessible to everybody, ideal for those that are starting to process astronomical images with PixInsight. It is also interesting to users of any skill level, since it explains how to put into practice a processing strategy based on solid principles, with the maximum respect to the original data.

Author's website: http://astrosurf.com/bosch/

We hope you'll find this new learning material useful and interesting.

If you have suggestions or need help, don't hesitate to contact us at support@pixinsight.com, or at PixInsight Forum:

   http://forum.pixinsight.com/

Thank you for your continued support,

The PixInsight Team at Pleiades Astrophoto

[Nocturnal]

Hi Juan and Daniel,

this is truly outstanding tutorial, again showing there are more than one road that leads to Rome (Barcelona).

For my clarification as this tutorial clicks with other things I've read, the star mask creation is a little different than that described in this tutorial:

http://pixinsight.com/examples/wavelets/NGC7000/en.html

in that the star mask is combined differently with the nebula mask. Last night I tried to create a mask for Atrous and it was a difficult task. Well, creating *a* mask is easy. The *right one* is hard I will try Daniel's approach as well.

Could you comment on the differences between the pixel math combinations (min vs * ~)?

[Juan Conejero]

Hi Sander,

Could you comment on the differences between the pixel math combinations (min vs * ~)?

Of course. Both techniques are valid to generate a combined mask, but I tend to prefer multiplication.

The Min function computes the minimum value from its arguments. The expressions:

Code: [Select]

Min( mask, star_mask )
Min( mask, ~star_mask )

will yield the least value of the mask and star_mask images (or the inverse of star_mask in the second expression) for each pixel. Where star_mask is black (white), this will obviously give black pixels for sure. An important characteristic of the above expressions is that they return either a mask pixel or a star_mask pixel, but never a combination of them.

Contrarily, the expressions:

Code: [Select]

mask * star_mask
mask * ~star_mask

will in general give values different from mask and star_mask pixels, except when one of the pixels involved is exactly one or zero, since it multiplies mask by star_mask (inverse of star_mask).

So the second expressions (multiplying expressions) tend to give smoother transitions between the (un)protected stars and their neighboring areas. The expressions based on Min() may yield more abrupt transitions just where mask becomes less than (or greater than) star_mask.

[Nocturnal]

Thanks Juan.

[Sean]

I'm updating my page of PixInsight links and have noticed that this tutorial is no longer available at the published link. Does anyone know if it is located elsewhere on the PixInsight website?

Thanks, Sean

[Dimitris Platis]

Cant find that tutorial!!

[Geoff]

Cant find that tutorial!!

Me too.  I get an http404 error (document not found)

[FunTomas]

Juan, could you please allow access to the old tutorials? Not only this one. All examples (Moon processing, using starmask, ...). Thank you.

[dayers]

Cant find that tutorial!!

Me too.  I get an http404 error (document not found)

This link also appears broken for me.

http://pixinsight.com/examples/intro/dbosch-ha/en.html

Dave

[Juan Conejero]

The problem with these tutorials is that they are outdated. Significant parts of these documents describe tools and features that are either no longer supported or superseded by new implementations. In some cases there are also old tutorials describing procedures that we no longer recommend or even identify as conceptual errors. These old works have been removed from our website for these reasons.

Unfortunately, we don't have the resources necessary to rewrite these outdated tutorials to keep them alive. From our experience, it is better to exclude them as soon as possible to prevent misleading concepts about PixInsight and practices that depart from our current methodological lines.

In the case of this tutorial by Daniel Bosch, I'm going to make an exception by revealing the URL were you can still access it:

http://pixinsight.com/oldsite/examples/intro/dbosch-ha/en.html

I'll consider the possibility to rescue this document for the new website, perhaps with some changes to make it up-to-date.

[FunTomas]

Thank you for explanation, but I don't agree. Maybe these tutorial contains outdated content or tools no longer supported, but they describe other useful techniques and procedures. PixInsight suffers from lack of documentation. In this forum is it possible to find too many requests for documentation... Removing old examples is unfortunate solution. I think that marking them as not supported or obsolete is sufficient. Many of these outdated tools are still available in PixInsight. Why not examples? I hope, that many users agree with me. Juan, please, return these tutorials. Please!

[pfile]

i agree with tomas.

rob

[georg.viehoever]

I also agree. Removing partially outdated documentation is not really the solution to the documentation problem that PI has.