This is the grayscale edit to yesterday’s question. Noticeably, you can see that the left side looks darker. However, without any light saturation, it is actually a lighter shade of blue. The peripheral of whichever side you choose as darker will make the other side appear lighter.
Correct answer: Right Side. Those of you who did mention the right side has confirmed it on PS.
Luke, I am your father. Join the dark side…
Well.. the left side looks darker.. and is indeed darker. I see no illusion in it (checked it in photoshop).
I think the left side is darker, but the right side appears brighter,