Quote:
Originally Posted by naskies
I see that you mapped the colours as R=SII G=Ha B=OIII... did you use object masks to balance out the extremely weak SII compared to the strong Ha?
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The image was done back in 2009 so I don't recall the specifics. All the images I work on I typically take notes on the processing. In the folder where the original files reside the notes entail that I used sum combine to get as much possible signal in SII. Keep in mind that the data was acquired with a camera that is back-illuminated with a QE of 95%+ so signal overall wasn't a real problem. The note also states that PS clipping masks were used to display each SII and OIII emission line evenly with Ha opacity dropped to 60%. The Ha was then relayed as a luminance to drop in more detail. Object masks were then applied to selectively boost the SII burnt orange hue and accentuate the OIII spikes as they radiate out from the center. I use object masks quite a lot in processing and they've come along way in CS5. CS3 were ever so painful and time consuming. Really Photoshop is based on masks. Its one of if not the most important aspects to understand and for the work we do with astro images, I find its usage critical as rarely would we want to apply contrast adjustments, filters, etc to the entire image.