Thoughts and Ideas on Photoshop
http://maclobster.blogspot.com/
#1 After opening the file in PS, go under the "Image" menu and choose "Image Size"
#2 Make sure "resample is on
#3 Switch from inches to % in pop up
type in 110%
#4 Press OK
Repeat till desired size is made.
Scott Kelby says this does not degrade the file.