Re: [APML] Stacking Software

[Roland Roberts <roland@astrofoto.org>]

>>>>> "Jose" == Jose Miguel Benito Huete <jbenito1@teleline.es> writes:

    Jose> So it is not the same a stack of two frames exposed half an
    Jose> hour each, that a single frma exposed for an hour. The stack
    Jose> of the two frmaes may have less backgound but the one hour
    Jose> single frma will have more signal.

The issue is that RegiStar only saves up to 16-bit/color, so while you
*can* add images if they are, say, 12-bit images.  If they are already
16-bit images, you need to average.  Your background will not go down,
but your S/N will.  

If you have rescaling selected, your background will go down because
RegiStar will have done a histogram stretch for you.  In this case,
you get the equivalent of adding multiple exposures except the final
result has been rescaled to fit in a 16-bit/color space.  I'm not
clear on how RegiStar is working internally; if it is adding in 32-bit
mode, then rescaling, you will get something quite good.

roland
-- 
		       PGP Key ID: 66 BC 3B CD
Roland B. Roberts, PhD                             RL Enterprises
roland@rlenter.com                     76-15 113th Street, Apt 3B
roland@astrofoto.org                       Forest Hills, NY 11375

--  APML Archives at <http://astro.umsystem.edu/apml/>  ---
             Unsubscribe at <majordomo@seds.org>