Photoshop from Adobe is a professional application and priced accordingly. There are plenty of other applications out there can help you get the job done. Some are free and others are very inexpensive.
Low Cost:
GraphicConverter (Mac Only)
Adobe Photoshop Elements (Windows, Mac)
Free:
The GIMP
Picasa Photo Gallery (Windows, Linux)
iPhoto (Mac – free on new mac or part of iLife for $79.00)