What color is the most reflective?

The scenery with high reflectivity, such as white or light-colored scenery, has strong reflectivity; Scenery with low reflectivity has weak reflection ability; Black objects do not reflect light.

Scenery with high reflectivity has strong reflectivity, such as snow with reflectivity of 98%; Scenery with low reflectivity has weak reflectivity, such as the reflectivity of carbon black is 2%; Generally, there are not as many subjects with high reflectivity as those with low reflectivity, and the average reflectivity is about 12.5%, so 12.5% is "neutral gray".

Experts know through experiments that the reflectivity of bare skin of white and yellow people is about 18%. As the embodiment of the principle of "people-oriented" photography, the basis of camera photometry is defined as the so-called "standard gray" whose reflectivity is 18% slightly higher than that of "neutral gray". The camera metering system regards the reflectivity of all different substances in the metering area as standard gray with reflectivity of 18%.

Whether it is sunny or cloudy, after automatic exposure, the photometric point of the photo displayed on the computer screen is the same as the visual brightness of the 18% gray board photo. According to the experimental results that the previous post may not be accurate enough, this brightness value is expressed by color scale, that is, 148, and expressed by gray scale, that is, 58%; In the histogram of color scale on camera and Photoshop, the middle color scale value is 128, and the gray scale is 50%. There is not much difference between the two.

Extended data:

Objects will appear black when they absorb all wavelengths of light, but why do some black objects also reflect light? This is attributed to two factors: the amount of incident light and the surface of the reflecting object itself. First of all, if there is not enough light, even red may be regarded as black.

Secondly, the black objects around us also have the difference between matte and gloss, which is related to the absorption and reflection ratio of incident light, and the most important factor affecting this ratio is the surface of the object.

Strictly speaking, only an ideal black object can absorb all the incident light. Even if the surface of the object is a little uneven, the object may reflect some light.

This can be tested when we walk at night: when we walk on the uneven road, we will find that the road surface is very dark, because the uneven road surface will diffuse at night, and the reflected light will scatter in all directions.

Under the same brightness, if we walk on a flatter road, the reflected light will be concentrated in a certain direction, and the road will look brighter. The same is true of black objects, such as the new black ball in billiards, which reflects light because of its very smooth surface.

Baidu encyclopedia-reflectivity