Optical Illusion - Castle Over Water

Explanation "How to do ?"

1. Keep staring at the dot in the first pic.

2. When the second appears keep staring at the dot, for a few seconds for your eyes it seems that the second pic is in colors which actually is not, just in black and white.

Song: Marvin Gaye - I Heard It Through the Grapevine. LINK: Youtube