Color vision is made possible with the photoreceptors in the retina of the eye known as cones. If the cones don't have a certain light-sensitive pigment, you will not be able to see one or more of the three primary colors. People with color blindness can have less than one kind of light-sensitive pigment and can only see the neutral or gray colors where a particular color would appear. As for the color weakness, their cones cannot distinguish colors of similar shades easily. For example, when red, pink, orange and purple colors are put next to each other, what they see would be lumps of similar colors. With the Color Weakness Mode on, the color weak can distinguish colors easily and gain quality time for clearer views.