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

[Vicent Peris <vicent@cepheusastrophoto.com>]

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:
> >
> >
>http://www.pleiades-astrophoto.com/pixinsight/examples/M1_JC_LargeScale.jpg
> >
> > I've processed this one over Juan's result to
> > enhance large scale features
> > of the object. If you raise the contrast of small
> > details, why not to raise
> > the contrast of large ones?? I think this is a more
> > complete processing,
> > since small scale and large scale features in the
> > image cause different
> > emotions to the spectator. But this would be another
> > independent thread! :-)
> >
> >
> > Well, that's all, for now.
> >
> >
> >
> > Take care,
> >
> > Vicent.
> >
> >
> >
> >
> >
> > At 13:12 11/10/2004 +0100, you wrote:
> >
> > > > Vicent Peris has processed one square degree of
> > DSS data for the B 142
> > > > region, AKA the "E" nebula.
> > > > See it at:
> > > >
> > > >
> >
>http://pleiades-astrophoto.com/pixinsight/DSS_Gallery/index.html
> > > >
> > > > I think Vicent's results are very impressive.
> > Hope you like it too.
> > >
> > >It's impressive, and a great illustration of the
> > functionality of the
> > >software...but as an aesthetic observation, maybe
> > it's been over-smoothed
> > >in the wavelets/noise reduction department? It
> > reminds me of "space-art",
> > >painted with an airbrush...to me it just lacks
> > reality, somehow.
> > >
> > >There's a story, which this image inspires me to
> > tell. A few years ago, I
> > >assisted a pilot research program of employing
> > deconvolution and
> > >wavelet-based noise reduction on digital
> > mammography x-ray images. We
> > >processed the images to "improve" them to our eyes,
> > and spent a long time
> > >optimising this. But the litmus test was a set of
> > clinical trials with
> > >radiologists at University College Hospital,
> > Galway. The radiologists
> > >evaluated the test images under various headings.
> > The tests were blind
> > >(the "before" and "after" images were presented
> > randomly), and our team
> > >repeated them several weeks later to check for
> > internal consistency
> > >(radiologists have excellent memories for image
> > details: you have to allow
> > >a long time to pass before presenting them with the
> > same set of data
> > >again, as otherwise they'll just remember their
> > previous judgements).
> > >
> > >The upshot of all this was that what _we_
> > considered to be better images
> > >(with rather aggressive processing) was not what
> > _they_ considered to be
> > >better. They were accustomed to seeing certain
> > levels
>=== message truncated ===
>
>
>
>
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Vicent Peris
http://www.cepheusastrophoto.com/Index.html

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