Luminosity Mask techniques pioneered by Tony Kuyper provide the highest degree of control over creative image developing and have become an essential image developing tool for me and many top outdoor photographers world wide. I think you will find this video series to be the most comprehensive visual learning resources for luminosity mask techniques available.
Home Page - http://www.outdoorexposurephoto.com/video-tutorials/the-complete-guide-to-luminosity-masks Video series includes:
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