Rotating an Image
Rotating an image is sometime necessary because most digital cameras and almost all scanners use a single orientation during picture taking or scanning. If you take a photograph of a person and hold your camera vertically, the image will still be in a horizontal  or 'landscape' view when opened. When an image should be viewed in a vertical position, that is called 'portrait' view.

A tool for rotating an image will be found in all image editing programs and the choices are usually as follows: 180 degrees, 90 degrees clockwise, 90 degrees counter clockwise and flip horizontal or vertical. The flip choice makes a 'mirror' image of the original. Flipping an image comes in handy when you've inserted a slide upside down in your film scanner. Advanced image editing programs will allow you to rotate arbitrarily in degrees. This is very handy when you just need to level out your horizon line.