I'm a member of the DSLR Astro Image Processing Yahoo group. If you're not familiar with it, they post unprocessed photos other members have taken, and challenge members to process them as they see fit. It's a great way of learning new processing skills!
The most recent challenge was NGC 6559 and I processed it in StarTools (see attached) and this is my workflow:
Cropped: X1=58, X2=4518, Y1=411, Y2=3142
Wipe - accept defaults
Develop: Digital Development=83.78&, all other defaults
HDR: Optimise Hard, all other defaults
Contrast: Compensate Gamma=Yes
Sharpen: Amount: 462%, Small detail bias:89%, Mask Fuzz: 17.2 (mask set around nebulosity)
Deconvolution: Inverse star mask, Radius=1.6 pixels
Life: Heavy preset, Glow Threshold=4%, Saturation=90%, Strength=100%
Color: Red Bias Reduce=1.03, Green Bias Reduce=1.03
De-Noise: Smoothness=84%, Brightness Detail Loss=22%, Color detail loss=22%
I received the following feedback from a member of the group and I would like to hear your thoughts on it please.
I'm not familiar with many of the processes in Star Tools, but I suspect that your Denoise may have been too aggressive. The nebulosity has an overly smooth look to it, so that's why I suspect the denoise process.
I'm not sure about what kind of masking capabilities StarTools has. However, one of the things that I would do in Photoshop would be to mask the noise reduction process using an inverted luminance mask. This makes it so that the noise reduction is concentrated on the background and faintest nebulosity. At the same time, it'll have minimal effect on the highlights (bright parts).
How would I go about doing what he says about creating an inverse luminance mask?
Any thoughts you could offer on his feedback plus my workflow would be greatly appreciated!