Reads an image "image_in.pgm" and:
 
 1. Creates and saves a copy of the image
 2. Inverts the image and saves the new image to a new file
 3. Sets all pixels to a specified brightness and saves the new image to a new file
 
 Creates an image with: 
 
 1. A filled box inside
 2. An outlined box inside
 3. A blurred copy of the image with an outlined box.
 
 Last edited: April 21, 2014