Re: [APML] OT: DSS image processed: Barnard 142/143 Complex ("E"Nebula)

[Chris Schur <comets133@yahoo.com>]

Vicent, go to my web site and pick out an image or
two, and Ill send you the raws to play with.  I have
been using sgbnr for quite a while now, so its
possible only small improvements could be had.  ;)

Chris
--- Vicent Peris <vicent@cepheusastrophoto.com> wrote:

> Hi Chris,
> 
> thanks for your words.
> 
> Yes, sure, your schmidt photos are very deep. But
> bring out that dark nebulas over the stars is not
> easy. I have been investigating during the last
> 4 - 5 months large scale processing; and the problem
> is that on the large scale wavelet layers there are
> information introduced by small scale / high
> contrast
> features. So to process properly the large scale
> features
> of an image, first you must have on the image ONLY
> that large scale objects: you must erase small scale
> objects on the image. It is possible, but it takes
> usually for me about 1 to 2 hours of work in
> PixInsight.
> 
> I encourage you to imake your way in large scale
> processing,
> your images will look as new, sure!
> 
> BTW, can I experiment with any of your images???
> 
> Regards,
> Vicent.
> 
> 
> 
> At 11:20 13/10/2004 -0700, you wrote:
> >Vicent, the power of this processing software
> >continues to amaze me.  Many of my schmidt shots of
> >dark nebula are like this, dark brown rather than
> >black inside, with brigh rims.
> >
> >Chris
> >--- Vicent Peris <vicent@cepheusastrophoto.com>
> wrote:
> >
> > > Hi Ray,
> > > I've made two crops of a selected area of the
> image
> > > at full size, before and
> > > after all of the processing:
> > >
> > >
>
>http://www.pleiades-astrophoto.com/pixinsight/examples/B142_Crop_Before.jpg
> > >
>
>http://www.pleiades-astrophoto.com/pixinsight/examples/B142_Crop_After.jpg
> > >
> > > As you can see, there is no data loss. In fact,
> > > there is much more
> > > perceptible data in the second image! Star
> colors
> > > are more differentiated:
> > > you can easily view the redder stars surrounding
> the
> > > dust clouds. On the
> > > other hand, brightness gradients on the clouds
> are
> > > also more defined, due to
> > > applied noise suppression and large-scale
> processing
> > > methods. Therefore, if
> > > you take into account only the *significant*
> data of
> > > the image, you'll see
> > > that the applied processing has recovered a lot
> of
> > > data which was invisible
> > > in the initial image. Really, do you think there
> are
> > > more things to see into
> > > the original?
> > >
> > > I think astronomical image processing has more
> > > things to do than enhancing
> > > the data and simulating that the image has not
> been
> > > processed at the same
> > > time. Astronomical image processing must say
> > > *something* to the spectator,
> > > leading to some emotional stimulus inside
> him/her.
> > > Representing the data
> > > collected at the telescope by just levels and
> curves
> > > adjustments doesn't
> > > suffice in many occasions, IMO, since our eyes
> > > *won't notice* all the
> > > existing data in the image.
> > >
> > > Let me explain this with an example.
> > >
> > > Here you have two images again. The object is
> M1,
> > > from the POSS II. The
> > > first image is the original RGB combination with
> > > levels and midtones
> > > adjustments. The second one is the same data
> > > processed basically with
> > > wavelets. All the processing work has been made
> by
> > > Juan Conejero:
> > >
> > >
>
>http://www.pleiades-astrophoto.com/pixinsight/examples/M1_JC_Original.jpg
> > >
>
>http://www.pleiades-astrophoto.com/pixinsight/examples/M1_JC_Final.jpg
> > >
> > > Download both images and save them on a
> directory of
> > > your hard disk. Then,
> > > look at the images with the Windows' viewer, or
> some
> > > similar program
> > > allowing you to change between both images
> quickly.
> > >
> > > If you take a look at the first image, and then
> you
> > > press the PgDown key to
> > > view the second one, you'll think: "Wow, the
> second
> > > image has a lot more
> > > detail!". But try pressing PgDown again and look
> for
> > > a second time the
> > > "unprocessed" image. Now you'll see more detail
> on
> > > the unprocessed image!
> > > Your eyes are now, after viewing the processed
> > > image, identifying subtle
> > > features near the noise level in the original
> image
> > > which were not being
> > > perceived before processing. This demonstrates
> that
> > > many features in the
> > > image must not only be perceptible to the
> spectator,
> > > but they must cause a
> > > *visual impact*. This concept is tremendously
> > > important! Why do you need to
> > > apply unsharp mask to an image?? Is this process
> > > bringing out details not
> > > present in the original image??
> > >
> > > As a pianist, I don't pursue achieving a
> > > naturalist's or reporter's work. I
> > > try to achieve a personal interpretation of the
> > > object that appears on the
> > > image, but, first of anything, RESPECTING the
> object
> > > and its nature.
> > >
> > > At this point, processing technics are
> essential.
> > > Think on astrophotography
> > > as a sum of forces. The sum of all of the forces
> is
> > > the visual impact. But
> > > these forces are in a fragile equilibrium
> because
> > > they are opposing each
> > > other: luminance vs. chrominance, small scale
> > > details vs. large scale ones,
> > > color balance, static vs. dynamic objects, etc.
> The
> > > more perfected a
> > > processing technique you have, the bigger visual
> > > impact you can give to the
> > > image, since the forces will increase, but the
> > > center of gravity will stay
> > > stable. Or maybe you want to do an unstable
> image
> > > intentionally, perhaps
> > > enhancing only small scale detail!
> > >
> > > But if you raise the visual impact of the image,
> > > noise will increase too!
> > > Therefore it is absolutely necessary to make a
> noise
> > > reduction to increase
> > > the visual impact of the image. Without noise
> > > reduction, you cannot exploit
> > > all of the expressive resources from the
> objects.
> > > This means that after
> > > processing there can be some areas on the image
> with
> > > no noise and also with
> > > no small scale detail, but this doesn't mean
> that
> > > you are losing detail!
> > > These are two different concepts!
> > >
> > > Now see this third M1 image:
> > >
> > >
> 
=== message truncated ===



		
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