DSA philosophy

[Ken Hudson]

This is my first post on a PixInsight forum.  As a new imager maybe I shouldn't even comment, but I feel compelled to chime in.  I read the DSA Founding Statement yesterday and I found it very well-reasoned and persuasive.  It very much matches my own philosophy - maybe that's why I like it.  

In my opinion, the signers of the DSA and the supporters of the DSA are exhibiting a fair amount of courage.  It's never easy to challenge the practices of others.  Inevitably, someone is going to get defensive.  Nonetheless, I think the issues raised by the DSA Founding Statement and the discussions in forums like this are very healthy.  If nothing else, these discussions force people to face this issue head-on and really consider how they want to contribute to the "development of the image processing culture in astrophotography" (quote from Juan elsewhere in this thread).

Finally, I was at the presentation by Lisa Frattare at the AIC (Adding Depth to Hubble Images for Hubble 3D IMAX).  I must admit that I was very uncomfortable with the amount of image manipulation that was described in her presentation.  I am not a film maker and I would freely concede that maybe the manipulation was necessary in order to create a 3D movie.  However, if that is the case it should be so stated in the movie credits at the end.  In my opinion, Hubble is a scientific instrument not an entertainment industry tool.  Yes, outreach is very important but I think there's a dividing line somewhere and I'm suspicious they crossed over the line.  If I'm wrong please feel free to educate me.

Just my two cents worth...

Thanks, Ken

[Michael Hernandez]

Just because you see those who do not agree with you as a threat

No I don't see anybody as a threat; I am certainly too old for that It is bad practices what is threatening astrophotography, not the persons. So the "those who" part of your sentence is inaccurate to describe what I think and what I have said.

Why you keep saying that?

Because some attitudes that I have heard and read (not here) indicate that the DSA initiative is being seen as a threat, or as something that requires a defensive reaction. We are not trying to go against anybody, but against bad image processing practices and its current proliferation in astrophotography (also in other documentary photography branches). Our intention is exclusively contributing to the development of image processing culture in astrophotography. Being seen correctly —that is, as we really are— is important and requires additional care on our part. I probably should have written this exactly as I've just written it here instead of the way I did it before, to avoid confusion.

You say you are addressing bad imaging practices, and I can understand that position. But when you use words like fraud, unethical, and honesty, then those terms are an attack against people, or are at least viewed that way. I myself don't feel threatened, actually I was more amused. I'm not laughing at you, but the website presents itself to me as proselytizing, kind of like a fire and brimstone evangelist at a tent revival. I notice there do not seem to be any more members to have signed on in the past year. Again, I am not trying to be negative, just trying to understand.

[Juan Conejero]

Hi Michael,

Situation 1:
Although I work with CCDs, my primary means for my astroimaging endeavors has been a Canon DSLR. These are known for severe horizontal banding when the image data is highly stretched. Now, the philosophy states that is is ok to correct for instrumental defects, but in a post above it is indicated that the use of an artificial background is prohibited. The only way I can see to recover the image is by using an artificial background to correct for the instrument defect. My only other choice is to throw away the data, throw away the camera, and quit astroimaging altogether. Background is not signal anyway, and I recovered every single little faint fuzzy. Here is the image in question: http://www.darkfireastro.com/images/M33.html.

Very nice image indeed. No, there's no problem at all with repairing banding. In fact, we have a nice and efficient banding reduction script written by Georg Viehoever. You'll find it on the Process Explorer window, under the Scripts > Utilities category (or under the corresponding options of the Script menu). Its name is CanonBandingReduction.

When I wrote "replace the existing sky background with a synthetically generated background" I was referring to a completely different thing; I now realize that I have been quite inaccurate; sorry for that. I refer to techniques that select the whole background (e.g. with a magic wand tool) and replace it with a (usually noise-free) synthetically generated background. Some of these procedures then add a certain amount of synthetic noise to achieve a more "natural" look. Although I can understand why these procedures are implemented, the background is part of the acquired data and due to its uncertain nature (its signal-to-noise ratio is very low) it cannot be selected with the necessary accuracy as to affirm that by replacing it in this way no object is lost. There are appropriate noise reduction techniques and tools to address these problems, which are much more respectful with the data.

[Juan Conejero]

when you use words like fraud, unethical, and honesty, then those terms are an attack against people, or are at least viewed that way.

We don't try or pretend to attack anybody. The paragraph of the DSA statement where these words are included is this one:

In the time of chemical photography the processing resources were much more limited than they are today, although it was much easier to distinguish between fair and false works. Today, unfortunately, there are frauds in astrophotography, despite the fact that a majority of authors work with absolute honesty and don't manipulate their images unethically.

The fact is that there are frauds and unethical practices related to astronomical imaging. For example, there are people that steal the works of others. Some users on this forum could put several examples. There are also people that purposely falsify images. These things happen. In the above paragraph, we are not talking about wrong image processing techniques, or techniques that we don't like, but about other conducts that are possible "thanks" to the power and versatility that digital imaging provides, in contrast to the time of chemical photography, when these things were much more difficult. That's all that the above paragraph wants to say, but perhaps we weren't clear enough, or we expressed it poorly.

the website presents itself to me as proselytizing, kind of like a fire and brimstone evangelist at a tent revival.

I'm sorry to read that. I don't agree but that's your opinion and I respect it. This is mine: we are not trying to proselytize; we have just formalized publicly our own vision of astrophotography.

I notice there do not seem to be any more members to have signed on in the past year.

That's true. In part that's because we haven't had the time to dedicate more efforts to the DSA project (you'll see that most of the website is under construction for a long time). And I suppose not a lot of people are interested. But if the amount of people interested were something to decide whether or not to start and continue a project, then not only the DSA, but PixInsight wouldn't exist since some years ago

[Michael Hernandez]

Hi Michael,

Situation 1:
Although I work with CCDs, my primary means for my astroimaging endeavors has been a Canon DSLR. These are known for severe horizontal banding when the image data is highly stretched. Now, the philosophy states that is is ok to correct for instrumental defects, but in a post above it is indicated that the use of an artificial background is prohibited. The only way I can see to recover the image is by using an artificial background to correct for the instrument defect. My only other choice is to throw away the data, throw away the camera, and quit astroimaging altogether. Background is not signal anyway, and I recovered every single little faint fuzzy. Here is the image in question: http://www.darkfireastro.com/images/M33.html.

Very nice image indeed. No, there's no problem at all with repairing banding. In fact, we have a nice and efficient banding reduction script written by Georg Viehoever. You'll find it on the Process Explorer window, under the Scripts > Utilities category (or under the corresponding options of the Script menu). Its name is CanonBandingReduction.

When I wrote "replace the existing sky background with a synthetically generated background" I was referring to a completely different thing; I now realize that I have been quite inaccurate; sorry for that. I refer to techniques that select the whole background (e.g. with a magic wand tool) and replace it with a (usually noise-free) synthetically generated background. Some of these procedures then add a certain amount of synthetic noise to achieve a more "natural" look. Although I can understand why these procedures are implemented, the background is part of the acquired data and due to its uncertain nature (its signal-to-noise ratio is very low) it cannot be selected with the necessary accuracy as to affirm that by replacing it in this way no object is lost. There are appropriate noise reduction techniques and tools to address these problems, which are much more respectful with the data.

I will be MOST interested to try to CanonBandingReduction tool, I have many, many data sets that were unusable due to banding. Once I discovered the cause of the banding, I was able to continue imaging without fear of bad data. I tried several banding tools in the past, but they've only been partially effective.

Unfortunately, in this image, I did as you described. I even fine-tuned the process further by creating a screened R, G, and B background, with random noise inserted, to simulate a natural background as would be given by a OSC. Except I almost never use magic wand, I used the select color tool, it is more accurate. Believe me, I pored over the image background selection to make sure nothing else was included. But that doesn't resolve the dilemma.

Can the CanonBandingReduction Tool be used last in the image processing, or is it necessary to do it early in the process?

[Michael Hernandez]

This is very interesting.  Like Rogelio I spoke with Lisa Frattare of the Hubble Heritage team at AIC last weekend and saw her presentation about the work that her group did for the Hubble IMAX 3-D film.  She had the designation of "star cleaner" in her group because she goes around with a paint brush tool and cleans up stars.  I could not tell if this was only for the work in the IMAX film where they were rendering 3-D images or for the standard outreach images that her group publishes on the internet.  For the IMAX film they were constructing 3-D fly-throughs of space, substituting galaxies and stars willy-nilly.  Since the point of view of these was extra-terrestrial I assume there could be no objection on DSA grounds for this work.

Mike

I have been having a verbal discussion with Lisa since her presentation, which has since carried on into an email correspondence. I have directed her to the DSA site, as well as the PI forum. I invited her to come on the forum, she and Zolt are very interested, but fear there might be "tomatoes thrown". I assured her that we are having a healthy discussion, I am finding all this fascinating (Mr. Spock twirling his imaginary mustache <g>)

[Juan Conejero]

Hi Michael,

You may be interested in the original forum thread where this script was first developed:

http://pixinsight.com/forum/index.php?topic=1159.0

In particular, take a look at the screenshots on the second page of the thread.

As all image calibration and preprocessing routines, the CanonBandingReduction script will work better at early stages, when the images are still linear (before the initial nonlinear histogram stretch). However I think it should also work with nonlinear images. I hope Georg will chime in because he is the father of this creature.

[Juan Conejero]

I invited her to come on the forum, she and Zolt are very interested, but fear there might be "tomatoes thrown"

She (or they) would be very welcome. Nah, we don't use to throw the tomatoes very hard  (joking )

We are always open to all opinions and enjoy constructive discussions, especially about very important topics like this one. Their contributions would surely be extremely interesting here.

[Juan Conejero]

Hi Ken,

I read the DSA Founding Statement yesterday and I found it very well-reasoned and persuasive.  It very much matches my own philosophy - maybe that's why I like it.

Welcome to PixInsight Forum!

Thank you for your support and nice words.

[Michael Hernandez]

Hi Michael,

You may be interested in the original forum thread where this script was first developed:

http://pixinsight.com/forum/index.php?topic=1159.0

In particular, take a look at the screenshots on the second page of the thread.

As all image calibration and preprocessing routines, the CanonBandingReduction script will work better at early stages, when the images are still linear (before the initial nonlinear histogram stretch). However I think it should also work with nonlinear images. I hope Georg will chime in because he is the father of this creature.

Wow, that's quite an extended thread. I've downloaded the latest version, and will be trying it as soon as possible. That may not be too soon, we are building two new obs. What will be interesting is if this also fixes the old "dark river" issue from the Canon 20D. Thanks for the reference.

[georg.viehoever]

...As all image calibration and preprocessing routines, the CanonBandingReduction script will work better at early stages, when the images are still linear (before the initial nonlinear histogram stretch). However I think it should also work with nonlinear images. I hope Georg will chime in because he is the father of this creature. ....

I am honored to be called the "father" of this script, but in reality it is based on ideas that I found in Jens Dierks's FitsWork http://www.fitswork.de/software/softw_en.php . I have been using it both in early stages of processing (i.e. immediately after calibrate+align+stack+debayer) and late stages just before the final noise reduction/stretch with nice results. I have the feeling that it might work even better if applied to the RAW images (fixing the slightly distorted statistics of the Canon images), but that would probably require implementing Bayer patterns in the script...which I have not implemented yet.

Georg

[vicent_peris]

Hello,

I wish to add a further reflection on the DSA topic. As you know, I started about 13 years ago doing amateur astrophotography and became professional about four years ago.

One of my main goals from my actual position is to open a small door to professional astrophotography.

The DSA statement is not anything to believe on. It's very simple: it is the particular concept about astrophotography by a group of astrophotographers. Instead of believing, to me it's more important to use the DSA statement as a basis for education.

Today in our discipline, there isn't any defined thought basement, and this reflects in the astrophotography community (in my particular teaching experience) because 99% of the astrophotographers need a better basic education. This is even more needed in the digital imaging area. In some aspects, a large amount of astrophotographers continue having a completely analogic conception of the digital image.

Having said this, to me is quite evident that a professional future for astrophotography can be a reality only if we advance in education. But this education cannot be possible if we don't know how to educate. The DSA is the first initiative in the world.

This is why, when I teach, I cannot separate DSA, education and PI.

For the moment, I consider the DSA a successful project. Just after founding it we started working at Calar Alto Observatory with a 1.23 meter scope. We have again 55 nights for next year. And we have published (and will continue publishing) some innovative works.

I think that an observatory must have a small portion of observing time for astrophotography and outreach. This is extremely hard to accomplish today, but we're working on...


Best regards,
Vicent.