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.