[AMRadio] Digital Pic help

[Phil (VA3UX)]

Sorry for the off topic post but I know there answer is out there somewhere.

when I take hi-res pics from a digital camera and then later re-size them 
to about 50%,  it appears that some sharpness is lost in the smaller 
picture.  Edges have a bit of a jagged look to them, etc.

How do I decrease picture size AND still maintain picture quality ?  Is it 
the "pixels per inch" that needs to be adjusted when decreasing size ?

Please reply off list. And again sorry for the O/T post but I don't know 
where else to go.

Thanks in advance

Phil