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

Well, all you must do is to know what are you doing with the image. It's essential to have a good dosis of auto-criticism to know if you are generating artifacts, as well as knowing how your eyes perceive the photo.

Vicent.

At 19:34 13/10/2004 -0500, you wrote:
If you think back to the "face on Mars" hoopla of several years ago you get an impression of background behind my question.  You take a 4-bit image (16 grey levels) and expand it to an 8-bit image (256 grey levels), than add interpolation and processing, with imaging artifacts included, you can generate a whole new industry! :)
 
I'll look at the 'without' image.
 
Thanks.
 
 
-----Original Message-----
From: astro-photo-bounces@seds.org [mailto:astro-photo-bounces@seds.org]On Behalf Of Vicent Peris
Sent: Wednesday, 13 October, 2004 19:10
To: Discussion of Film Astrophotography
Subject: Re: [APML] OT: DSS image processed: Barnard 142/143 Complex ("E"Nebula)
Hi Richard,

no, I'm not "generating" data! If you take a look to the image with the stars
removed, you will view that there are a lot of gradients that are not visible
due to the high density of the star field:

http://www.pleiades-astrophoto.com/pixinsight/examples/B142_woStars.jpg
Simply, I'm enhancing that gradients over the stars to make them visible to
the eye, that's all!



Regards,
Vicent.



At 19:00 13/10/2004 -0500, you wrote:
This is not intended as a criticism, but a question; the hairs on my neck go
up when the "invisible" is "revealed".  Is it REALLY exposed data or is it
processing artifact?

If it is intended, as suggested by comments that I trimmed off, that the
resulting images are for "artistic" presentation then I have no problems.

On the other hand, if the resulting images are for scientific analysis, have
you revealed information or manufactured data?

-----Original Message-----
From: astro-photo-bounces@seds.org
[mailto:astro-photo-bounces@seds.org]On Behalf Of Vicent Peris
Sent: Wednesday, 13 October, 2004 09:24
To: Discussion of Film Astrophotography
Subject: Re: [APML] OT: DSS image processed: Barnard 142/143 Complex("E"
Nebula)



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?





        ... trimmed ...

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Vicent Peris
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