Eyesight is a remarkable thing, but it's also imperfect, which is exactly what optical illusions seek to take advantage of. In this one, you'll be able to trick your eyes into seeing a black and white image in full color.
Cone cells are one of the types of photoreceptor cells in the retina, of which most people have three subtypes that are each sensitive to either red, blue, or green light. They function well in stronger light and are responsible for our color vision, which is why discerning color becomes more difficult in low light, as rod cells (which only come in one variety) take over. It turns out that these cones can be "exhausted" in a sense; namely, if they are exposed to a certain color too intensely, they temporarily lose sensitivity, and vision skews toward the complementary color. To use this in an optical illusion, a researcher has a participant stare at an image with intense false color for a few seconds while the brain adapts. Then, the image suddenly flips back to black and white, but to the participant, it appears as a true color image before slowly adjusting back to normal. It's a neat trick that you can try for yourself in the above video!