On this video N.Y. based photographer Chris Knight demonstrates an advanced way of selecting and replacing a background on a portrait in Photoshop.
This video is all about the background and how you can select your subject with maximum accuracy in order to separate and replace the background using the blue channel (in this case) and a mask.
What seems to be lost in the final image Knight shows is the shadow and this is actually something that we would like to preserve in some cases when we are not completely replacing the background but only making it smoother. You can check out a previous video we posted here by Aaron Nace from Phlearn that looks at cleaning a background in Photoshop instead of replacing it completely.
Finally, If you have the time – jump down to Knight’s website – he has some very powerful portraits worth checking.
You can find many more Photoshop video tutorials on LensVid’s Photoshop section.