Re: [APML] Orion's Sword Reprocessed

["Carlos Milovic F." <cmilovic@yahoo.es>]

>   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.

If the background is smooth, without stars, it is
correct. Even so, I would try to decrease the
tolerance, and then reject a few pixels. Surelly those
pixels are noise, no real data.

By the way, I asked you about the position of the
sample boxes, becouse if you put them over faint
nebulaes, DBE will adapt the function to those values,
and later, when you substract or divide, you'll lose
the information of those nebulosities. You have to be
very carefull. If you are not sure, look very deep
pics from other guys. 

>   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?

You didn't understand me... I was talking "after noise
reduction", i.e. SGBNR or wavelets. 

DBE works best with RAW data. Or at least with the
background level substracted (the film base, or ccd's
bias and darks). Think of those steps as calibration
procedures, not image threatment itself.

 
>   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.
>     

There is a process called "ExtractChannels". Open it.
Select the CIE L*a*b* color model, and uncheck the a*
and b* channels. Now, apply this process to the image.
The luminance will appear as a new, grayscale, image.

BTW, you can change the way the luminance is
calculated ... read the documentation chapter
regarding Color Management and Working Spaces.




Regards,

Carlos Milovic F.
-------------------------
Astro & Photo - CMF
http://www.astrophoto.vze.com
-------------------------
Visita "AstroFoto", el foro de astrofotografía en español
http://espanol.groups.yahoo.com/group/astrofoto


		
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