Direct light - direct light is light from a light source (such as the sun) directly to your eyes. Excessive direct light will make the details of the surrounding environment blurred, but also make it difficult for you to focus on the line of sight.
Reflected light - reflected light is often in the form of glare. The reflected light is the light that is reflected back from the object on a reflective object. Like direct light, intense reflections make it difficult to perceive detail or look directly at an object. Snow, water, glass and white sand are very good reflection surface.
Diffuse light - diffuse light is a rebound in the direction of many scattered light, so it seems that the light does not have a specific light source. A typical example of diffuse light is the glow above the big city. It is difficult for us to determine a single light source. In the absence of a direct light source, we can see things, this is the credit of the credit.
High-quality sunglasses can eliminate ultraviolet rays in the spectrum, reduce direct light, make people feel comfortable, but also to eliminate or reduce the reflected light (depending on the reflective surface).
An interesting feature of light is polarizing. When reflected from certain surfaces, such as water, the light will polarize. Due to the polarized nature of the reflected light, the polarized sunglasses can eliminate the light reflected from the water surface or the like.