Definition of the ray traced image file:

offset   length   Type            Description
------   ------   ----            -----------
  0        2      unsigned short  File id and version number.  This is 015C.
  2        2      unsigned short  Pixels per line
  4        2      unsigned short  Lines in file
  6      250                      Extra space, set to 0.

Starting at offset 256 come the values for each pixel.  There are 3 bytes 
per pixel, first the red value, then the green value, then the blue value.  
There are Pixels * Lines of these.  Then the end of file.
