The description provided under this video on YouTube says it all:
When Tatsuo Horiuchi retired, he decided to try his hand at art. But instead of spending money on paints and brushes, Horiuchi used what he already had pre-installed on his computer—Microsoft Excel. Now, the 77-year-old artist is creating remarkably intricate digital masterpieces of the Japanese landscape, all on the free graphing software.
Check out the amazing video and the unbelievable skills of Mr. Horiuchi.