An optical illusion Photograph

For me, art is a game: I like to experiment with colors and shapes. I specialize in digital art and mostly use Gimp freeware. I just start from something (a blank screen or sometimes also a photo I have taken before) and "play" until I like the result. Still, I create my art pieces, not the software: I select colors, effects, areas on which to apply these effects, I also draw some lines and other shapes etc. Sometimes it takes minutes, sometimes hours or even days until I feel that it is ready. So far, I have only managed to sell one print here (of "A blue globe" that you can see here: ).