It's very interesting how easy it is to see color noise in a photo but something else to remove it without degrading the picture. I was using an older camera one warm night at Momo lake and took several long exposures of the tufa and north star. I've included two screen shots of the foreground and stars where you can see lots of color noise. Yes I've played around a lot with "dust and Scratches" and can't remove the color noise without degrading the picture. If I use 4-5 radius in "Dust and Sratches" I can get rid of the noise but soften the tufa and wipe out about half of the star trails. The color noise is obvious to the eye. It's also pretty obvious when you look at the channels. I've tried a bunch of other stuff trying to create a mask for the noise with little luck. If anyone has any suggestions I would appreciate it.