Recent Posts

51

General / Re: What is a documentary criterion for an image?

« Last post by dld on 2020 March 03 03:58:55 »

I will attempt to give a short answer to this very tough question which require both knowledge of history of photography and science. I don't claim expertise in both subjects. Given the fact that astrophotography reached the masses later than photography, one may look for answers through the history of photography. 

If astrophotography belongs to the genre of documentary photography, it must provide a straightforward and accurate representation of objects and events.

But...

Contrary to popular belief, any photograph is a subjective representation of reality. Even the act of seeing a photograph is subjective, since our eyes are poor optical instruments and require the intervention of the brain to conceive the image.

With that in mind, the question becomes, "what we want to achieve by presenting the viewers an astrophotograph?". Some possible answers may be:

To attempt a faithful representation of an astronomical event.
To educate the viewer about astronomy/astrophysics and the scientific method.
To demonstrate our processing skills.
To show off our expensive equipment.
To earn prizes in well-established contests.
To earn "likes".

Depending on the answer(s), one chooses where the line is drawn.

52

Bug Reports / Re: Cannot Attach Image To A Post

« Last post by Juan Conejero on 2020 March 03 03:36:11 »

Hi Dave,

Thank you so much for your help

I've just installed the mod and nothing has changed. I'm going to investigate server settings. Also moving this thread to bug reports, just to keep it more visible.

53

Bug Reports / Re: Invalid memory read operation on two seperate windows machines

« Last post by mhellaby on 2020 March 03 03:36:04 »

Thanks for your reply I guess it’s just bad luck that it’s happening on both of my machines - I’ll have a read up to see what I can do Linux wise on my PC if not I do have an older Mac laptop just a pain when I set up a high spec windows device purely for PI and processing

54

General / Re: What is a documentary criterion for an image?

« Last post by dave_galera on 2020 March 03 03:25:28 »

Can you define what exactly what is meant by 'painting' and what context 'painting' would be used....just for clarity?

55

General / What is a documentary criterion for an image?

« Last post by Geoff on 2020 March 03 02:52:54 »

From time to time the topic of documentary criteria is mentioned in a post. Can anyone point me to (or give me) a succinct summary of what exactly is encompassed in the term “documentary”?
Clearly, arbitrary selections and painting are not “documentary”, but a histogram stretch is. Where is the line drawn?
Geoff

56

General / Re: Mosaic Problems . . . Can't Image Solve after a crop?

« Last post by bulrichl on 2020 March 03 01:57:32 »

Hi Terry,

when Image Solver script fails, it generates the following error message:

-------------------------------------------------
Please check the following items:
- The initial coordinates should be inside the image.
- The initial resolution should be within a factor of 2 from the correct value.
- Adjust the star detection sensitivity parameter, so that the script can detect most of the stars in the image without mistaking noise for stars.
- The catalog should be matched to the image. Choose the appropriate catalog and magnitude filter, so that the number of stars extracted from the catalog can be similar to the number of stars detected in the image.
-------------------------------------------------

Currently (PixInsight 1.8.8-5), the crop process removes the following FITS keywords from the FITS header:
XPIXSZ, YPIXSZ, FOCALLEN, RA, OBJCTRA, DEC, OBJCTDEC, EQUINOX

The coordinates RA, DEC of the FITS header are used as seed parameters by the ImageSolver script. If these data are not present in the FITS header, the coordinates that are set manually in the ImageSolver script are used. If the manually set values are wrong, ImageSolver will fail. In addition, the manually set values for image resolution must consider any drizzle scale!


Please also see the discussion about whether it is really necessary to delete astrometric solutions when the crop process is applied: https://pixinsight.com/forum/index.php?topic=14592

Bernd

57

Bug Reports / Re: Invalid memory read operation on two seperate windows machines

« Last post by Juan Conejero on 2020 March 03 01:35:19 »

I have not been able to reproduce this problem after many intensive tests. However, the '0000000000000008' access violation error is similar to the same problem that was reproducible in version 1.8.8-4 after recent Windows updates. This problem has been avoided in version 1.8.8-5, although obviously not completely, as this report demonstrates.

There is little more I can do to prevent these problems from happening for now. These access violations don't originate from our code, and there is no way to reproduce them consistently. This does not happen on FreeBSD, Linux and macOS executing exactly the same code, and most of the time it doesn't happen on Windows either. I am very sorry for these issues, and will keep doing my best trying to solve them. For maximum stability and performance, I recommend running PixInsight 1.8.8-5 on Linux.

58

General / Re: Give me a reason to stay....please!!!

« Last post by Juan Conejero on 2020 March 03 01:13:17 »

Hi Rodd,

As you call me here, let me give you my personal vision on this subject. Please don't take the following as an attack, but only as the truth about my idea of what is astrophotography, which is also the underlying philosophy behind the PixInsight project. I am not trying to convince you or anyone else; this is only my personal opinion.

You don't really need reasons to stay here. What you really need is to ask yourself why you are doing astrophotography, or in other words, what do you think is astrophotography and what can it give to you personally.

PixInsight has not been conceived and designed, and is not being developed, as a tool to paint images. If you want to paint, PixInsight is probably one of the worst tools you may find for that task. Photoshop and similar applications are much better for that. Photoshop will always win to help you build absolutely stunning and wonderful pictures, simply because nothing can compete with arbitrary manipulations to give you exactly what you want to achieve, when and where you want to achieve it.

An accomplished imager just posted an image of Markarians Chain taken with an FSQ 106--a 4" refractor--wide field.  BUT, he inserted long focal length data captured with a bigger scope into the galaxies.

There are different ways to do this, and in some cases it could be more or less justifiable, depending on the context where the image is going to be used and how it will be presented. But this is painting, and the resulting picture as a whole is not a fair representation of the acquired data. It has been arbitrarily manipulated without a global criterion based on physical properties of the represented objects. It has been painted this way just to make it look 'nice' without any documentary criteria.

Yes, this can be done in PixInsight, and some users have described procedures that should work well. However, nothing in PixInsight can compete with Photoshop to achieve this. A couple layers, a few brushes, a put this here and move that there, et voilà, job done.

PixInsight is a tool to help you develop your astrophotography through the knowledge of image processing. Astrophotography, with all the technical and artistic challenges involved, is a path of personal growth. The why and the how are much more important than the final product.

59

Bug Reports / Re: Invalid memory read operation on two seperate windows machines

« Last post by mhellaby on 2020 March 03 00:40:07 »

Just as a follow up - there are a few people mentioning this on a Facebook PI group - it seems to be linked to the integration step either within WBPP or when run as a separate process

60

General / Re: Parallel disk processing in PixInsight (setup) questions

« Last post by dpastern on 2020 March 02 22:59:27 »

Hi Pierre,

Thanks for explaining it to me.  I'll try it with the current SSD, the o/s SSD and I'll see if I can create a RAM drive.  That gives me 3 tempfs points. 

Then I'll re-test.

Cheers,

Dave