Processing continued
At this point the images, luminance master (16 Bit
FITS) and RGB TIFF, are opened in PhotoShop CS2. I usually start with the RGB
image. At this point you want to adjust your levels in each channel. Do your
final tweaks such as color balance, sharpening and noise reduction. When you are
satisfied with the result, save as a new image and also save as a PSD file so
you can go back and change or add to it later. Then I do the levels and
sharpening with the Luminance image. Once again when you are happy save as a new
image.
This is where I'll combine the new Luminance image with
the new RGB image. All other images are closed with exception of the above new
images. with the Luminance image active, Select All and then Copy. Make the RGB
image active and then paste the image over the RGB. In the Layers Palette ,
choose Luminosity as the blend mode. Go to Layers and Flatten the image. Make
any necessary changes such as color saturation. When satisfied with the new
L+RGB image, save as a new image file. I usually save these as a 16 bit TIFF
before saving for the web as JPEG files.
Keep in mind that these are basic guidelines. Depending
on the amount and quality of data will determine how much you can enhance the
final image. As a rule these days, bright nebula I'll image a minimum of 2-3
hours at 1x1 for the luminance and 45 minutes to 1-2 hours binned 2x2 for each
channel. Dim objects such as galaxies, it's not uncommon to image the luminance
data at 1x1 for 8-10 hours and color for 1-2 hours each channel binned 2x2.
Rob Gendler has an
excellent paper on merging Ha data with the image. Be sure to check out many
good articles on his site. He also has an excellent astronomy
Beginner Primer.
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