OK I know this isn't retouching but it may help
I wanted a defuser but being cheap I didn't want to spend a lot of money
after reading rangefinder report on defusers I tried one tall rubbing alcohol
bottle frosted white in color,top cut out and a couple velco strips to keep it on the flash head
You loose one f stop, but so do all the other commercial defusers.
You get the slightest gold tone to the picture if left in auto wb.
Very pleasing effect,very even light spread, and very cheap to make.