Re: [Canon_DSLR_Digital_Astro] Re: Question about advantages in .post-processing


Jun 28, 2010

 


----------------------------

#41566 Jun 28, 2010

Thank you all for your answers.



Your points of view have been very useful.



Best regards,



Alfredo

On Sun, Jun 27, 2010 at 6:41 PM, chuck kimball artists@...>wrote:



>

>

> agreed Blair, but most of us are not toing photometry... like Gedas, just

> making purty pitchers...

>

> with a little effort, photoshop can divide a flat... just invert and

> multiply, but finding the right curves and values can be a bit tricky...

> best to let the atroware do that part... imho

>

> I use both, as I mentioned earlier... just habit I guess.

>

> chuck k

>

> On Jun 27, 2010, at 4:31 PM, Blair MacDonald wrote:

>

>

>

> I tend to fence sit on this issue. If I were a true purest I wouldn.t use

> and non-linear stretch because that destroys the photometry!

>

>

>

> But to answer Alfredo.s original question from my own personal perspective,

> I simply haven.t found an astro only package that has the flexibility of a

> more general image processing package for making that final pretty picture.

> Stan very correctly points out that astro only packages are much better at

> maintaining the integrity of the data, but at a loss of capability in the

> final image presentation. With layers and masks I can implement any spatial

> varying process I like, whether it be a filter, a noise reduction or a

> contrast stretch. These general packages do seem to be rather limited in

> their calibration ability however. Does Photoshop allow a proper image

> division for flat field correction yet? As a result most people tend to use

> a dedicated astro processing package for calibration, stacking and some

> initial image work mostly because these packages are better suited to the

> task. Then with an initial calibrated and stacked image in hand, more

> general image processors seem to be better suited to bringing out particular

> details that we want in the final picture. At least as of yet I have not

> found a single program, astro or more general processor, that will do

> everything I want so I simply use both for what they do best.

>

>

>

> Blair

>

>

>

> *From:* Canon_DSLR_Digital_Astro@yahoogroups.com [mailto:Canon Canon>_

> DSLR_Digital_Astro@yahoogroups.com] *On Behalf Of *Gedas

>

> *Sent:* June-27-10 3:52 PM

> *To:* Canon_DSLR_Digital_Astro@yahoogroups.com

> *Subject:* Re: [Canon_DSLR_Digital_Astro] Re: Question about advantages in

> post-processing

>

>

>

>

>

> Stan, boy, talk about tossing a hand grenade LOL. Ya gotta remember, as far

>

> as astro imaging goes, 99% of us here on this group are here as artists in

> one form or another, not scientists. Preserving data accuracy for science

> is not at the top of my list when I process. It could be but I choose not

> to do so. If I were doing this for a living I would have a different work

> flow and use different tools. When you talk about punched up images with

> gaudy colors etc, etc it reminds me of the worlds "greatest" artists like

> Van Gogh, Picasso, Dali, Monet, etc, etc. So what's the big deal ???

>

> My take is that as long as I don't "paint" information onto or into my

> images, and as long as I bring out what is already there, I'm ok with that.

>

> I am here to make purdy pictures. Anyway, I'm curious, in your opinion what

>

> true astro processing software is at the very top of the food chain?

>

> Gedas,

> gallery at gedas.me

>

> Light travels faster than sound..

> This is why some people appear bright until you hear them speak.

>

> ----- Original Message -----

> From: "stan_ccd" stan_ccd@... stan_ccd%40yahoo.com>>

> To: Canon_DSLR_Digital_Astro@yahoogroups.comCanon_DSLR_Digital_Astro%40yahoogroups.com>

> >

> Sent: Sunday, June 27, 2010 1:06 PM

> Subject: [Canon_DSLR_Digital_Astro] Re: Question about advantages in

> post-processing

>

> > --- Alfredo Beltran albeltrang73@...> wrote:

> >> I'd like to know what is the real benefit when doing

> >> post-processing in Photo Shop, vs doing it in any astronomical

> >> software as MaxIm or ImagesPlus.

> >

> > For the most part, astronomical software does "processing" and not much

> > "post-processing". Good astro software will competently calibrate, stack,

>

> > and data-reject (largely a sub-function of stacking) to produce a deep

> > master image (32 bit per color). Additionally, such software provides

> > basic scaling and conversion functions such as DDP (the 32 bit "image"

> > cannot actually be seen and must be scaled to 8 bits per color). And the

> > software should provide appropriate color balance functions, which have

> > unique demands for astro; in particular sky pollution is unique to astro

> > imaging and must be removed in a way that is generally not facilitated by

>

> > normal photo software.

> >

> > The result of competently wielded good astro processing software is a

> > basically "honest" image that accurately portrays the data. However, the

> > honesty of such images can easily reveal flaws in the equipment and

> > operator errors, which is why Photoshop and its ilk are often employed

> > (IMHO, it is better to learn from those mistakes rather than attempting

> to

> > disguise them).

> >

> > Additionally, some people like to "punch up" their images with gaudy

> > colors, over-sharpening, "noise reduction", ad nausium, which is also the

>

> > domain of Photoshop et al. I know some people who spend more time fudging

>

> > their "artistic creation" in Photoshop than they spend acquiring and

> > processing the data. Some viewers may say "wow!" but I cringe when

> viewing

> > such unnecessarily goosed-up (or even falsified) images.

> >

> > It should also be mentioned that Photoshop is sometimes employed as a

> > substitute for astro processing software. It is a very poor substitute

> > but many terrestrial photographers are already comfortable with the

> > program and having already spend a fortune on it are reluctant to buy and

>

> > learn good astro software. This is somewhat common for DSLR but rarely

> > done for real astro CCD because Photoshop is not designed for that

> purpose

> > (awkward to use) and it does not do a good job (cannot even perform some

> > basic astro optimizations).

> >

> >> I know this can be a very controversial question

> >

> > Why do you say that? g>

> >

> > Stan

> >

> >

> >

> >

---------------

> >

> > Yahoo! Groups Links

> >

> >

> >

>

>

>

>

>





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