How Many Cubes?

How many cubes do you see in this optical illusion picture? I only see 6 cubes. What about you? Do you see more than 6 or 7 cubes?
Update: Thanks to Tim who let me know there are 13 cubes in this illusion pictures. There’s the 6 cubes where the black is the top of the cube, and then another 7 if the black is facing you.
Tips: If you want to see 7 cubes, you have to look at the black color of the image for a few seconds. If you want to see 6 cubes, you have to look at the blue color for few seconds too.
Source: How Many Cubes