Re: [APML] NGC 2903 OT

["Tony Hallas" <tonyhallas@foothill.net>]

Hi Stuart,

    It's a bit more complicated than that ... you start with a 16 bit image,
in this case a Tiff file ... it is the result of all the reduction that you
did on the CCD data prior to "opening" the image. Unlike a film image, a
good CCD can grab the 16 bit data right out of the sky. What this does is
give you a much greater range of densities than is possible with film, all
in one image.

     So using curves in PS, it is possible to open this image to different
levels ... you can open the image to the very faintest levels ... this will
show all the faint fuzzies and also all the noise in your image. You can go
back to the original file and this time open it to the threshold of noise
showing up. You can open the original file so that the core detail in the
galaxy is maximized. If you save all these images you now have a palette to
draw from and construct an image that has the best of all features. I can't
tell you exactly how I combine the noise-free background with the faint
fuzzy one and keep most of the fuzzy detail, but I can tell you that it
utilizes layers and a form of masking. The nucleus detail can be "cut and
pasted" into the image like working with M-42.

      Does this relate to anything with film? It might if you blur one image
for "smoothness" and combine it selectively through a mask with the "detail"
layer ...

     Clear skies,

         Tony

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