Optical Illusion...thoughts, comments

[Wavelength]

Now you know INDIA creates illusion lolz
My God first i saw recessed; then i saw raised; the same thing can happen even in the second image; finally i conclude it is raised.... i must soon escape from this, before i go mad; good bye

[MrB]

The second (colour) image confirms the raised pattern - the tops are polished by wear and the channels between are rusty from the water that will linger for longer there.

Philip

[Brownbear]

raised... hard to tell from the 1st image but from the 2nd image they look raised to me

[Jims]

Reminds me of the left brain right brain optical illusion test with the rotating dancer image... I saw recessed initially but on second look it all became raised. then I read comments about the shadow and saw the larger image! I can nit get my eyes to see recessed again!

[MartinJ]

But then try flipping the image vertically...

[pasusan]

The black pairs are recessed. The raised areas are rusting because the paint is worn off.

Logic always wins. I think...


Thanks Jack for the image - I like patterns myself and the monochrome treatment suits it.

[Dusty]

To me the easy way how to tell is to look where the direction of the light is coming from and look at where the shadows fall. Always look for the direction of light and shadows.
Dave.

[flashback]

The majority are correct, the pairs are indeed raised to allow for drainage. I will admit that the first posted photo was cropped to facilitate the illusion, but in the second it's a bit clearer (Like Nandakumar, every time I look at the pics, they jump from recessed to raised to recessed to...well, you get the idea).
Initially I took the photo because of the pattern. It wasn't until I was playing around with it that I realized the optical illusion.
Which now leads me on a quest to find more such illusions.
Thanks everyone for viewing and commenting.
Anyone else have something similar?