This challenge is designed to test your observational skills and your ability to process and identify variations quickly. Remember, the key to success lies in patience and attention to detail.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
Answer:
Actually, there is no curved blue line at all. The curve is formed by the small white boxes inside. Due to the image retention properties of the eye, when you glance around the image, you will experience such an illusion.
