Average filtering, median filtering, and Edge detection

The program should do the following:

 Prompt the user to enter a file name.

 The program should open the file provided. You can assume that the file will be a PGM image file (described below). If the file does not exist, or is not properly formatted, your program should exit.

 The program should run an average filter on the image and save the result as “average.pgm”.

 The program should run a median filter on the image and save the result as “median.pgm”.

 The program should run an edge detection on the image and save the result as “edge.pgm”.

 The program can then exit

So bascially the program is filtering pgm file