from within iPhoto.
You get a number of choices, basically small, medium or large.
No need to go messing with your pictures
I am trying to enlarge and/or make smaller a number of pics carried in my iPhoto folder. I am unable to locate the area where I can change the number of pixals when I transmit the pic in mail. Is there a specific area I can do this? I am using a MacBook Pro with LION.