Creating a battleship space board

I have to write code for a display board for a battleship type game. I am having trouble figuring out how I would display a board that can change/has different colors. My professor suggested filling in pixels of an image to create the board, which resembles this code: image(255.*~displayBoard); colormap gray; axis off; However, I am not too sure how I can create a similar code to get the type of board that I need or how to go about this. Thanks in advance.