You must have started with a JPG or PNG of your eyeball.
It is simply your use of a PC program to create the bitmap as a C array.
There are several formats for the array e.g. XBM or regular BMP.
Then you use the appropriate method to display it.
Post a link to the original artwork or just insert the image to your message.
From memory, the tutorial shows you how to create the C array.
David.