Spectral distribution


Each light source has its own energy distribution at different wavelengths. This characteristic is called "spectral distribution”. For example, the drawing below compares different kinds of light sources. Incandescent bulbs look more yellowish or orange than fluorescent bulbs or LEDs and generate more heat. The graph shows that they contain more red components and infrared radiation than the blue side.


<aside> 💡 Obviously, these drawings are not precise. They are only intended to give you a rough idea. 見ての通りこれらの図面は厳密なものではありません。あくまで、大まかなイメージを伝えるためのものです。


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The surface of an object absorbs or reflects different frequencies of light at different rates. For example, the surface of a yellow lemon and red strawberry look like the drawings below.


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Multiplying the light from the source by the reflectance of an object shows what distribution of light is reflected from that object. In the demo below, the yellow line is the spectrum of light and the pink line is the reflectance properties of the object, and the thick white line is the multiplication of the two, which is the actual light reflected.



Cones and light perception