----- Original Message -----
Sent: Tuesday, March 15, 2005 6:30
AM
Subject: Re: [APML] Orion's Sword
Reprocessed
Hi Carlos,
Looking at it with fresh eyes this morning, I see
what you mean.
>It might be just a wrong impression, but maybe you put some DBE
samples in regions with some faint nebulosities near M42. Did you carefully
check that they contain only backgrond pixels? Did you substract the
result?
When using DBE, my sample points are totally white in the little
sample preview box. Is this correct? Mine didn't look like the
model in the tutorial using a .5 tolerance.
>I would suggest new histograms and curves adjustements after the
noise reduction, becouse now you have more avalaible dinamical range.
I did all histogram and curves after the DBE. Should DBE be done on
the raw scan or should I do a small histograms and curves before AND after
DBE?
>It is a quite tricky process, but you can generate a mask to isolate
the core of M42... Just as a suggestion (I think that it would work...):
Extract the luminance and then duplicate it twice. Blur one of the duplicates
with wavelets, disabling the first 8 or 16 pixel scales. Substract the result
to the other duplicate, without rescaling. Close the first duplicate.
Substract the second duplicate to the original image, without rescaling again.
If it worked propperly, you have deleted most stars from the image.
Now, use histograms to isolate M42's core and set the propper
transparency of the mask. Finally, don't forget to invert the image, so it
will allow processes to be applied to the zone you want.
I will try this process but I have a dumb question...how do I extract the
luminance? The tutorial called for this in making the SGBNR_mask but
since I didn't know how to do that, I just converted it to grayscale.
>Well, now some suggestions regarding your image's look. It lacks a
bit of saturation, specially in the blues. Use Curve's saturation to increase
it.
I didn't like very much the look of M42... the outer regions have too
much constrast to the inner ones.
Ok, I'll work on the saturation and balancing the contrast.
>Despite my above critics, it is a very good image, and the use of DBE
gave it a new look, by far better (more "professional"). Congratulations.
Thanks Carlos, I'll redo it trying your suggestions tonight.
Gary