Reading Notes

As mentioned above, the color of everything is produced by the reflection of light on the surface of the object. It is light that creates colors, and at the same time, light also creates shadows.

Where light shines is the light source. There are two common light sources: illumination light and ambient light.

It is the main illumination light in the picture and the core light source that affects the overall light and shadow. According to the different irradiation paths of light, irradiation light can be divided into direct light, scattered light and refracted light.

1. Direct light: Direct light is directly radiated by a light source, and the light direction is a clear straight line, which is concentrated and focused as a whole.

Direct light can form a strong contrast between light and shade on the surface of an object, which is too stiff and can form a clear outline edge. The most common direct light is sunlight. There are also artificial lights such as flash and constant light (without soft mask) commonly used in photo studios.

2. Scattered light: When the light beam passes through a certain medium (cloud or soft cloth), it can be dispersed and spread by the surface of the medium. The light path of scattered light is multi-directional, scattered as a whole, and there is no clear direction.

Among natural light, the light on cloudy, rainy and foggy days belongs to scattered light. In artificial light, the flash and constant light in the studio are also scattered light when covered with a soft mask.

3. Refracted light: the light whose propagation direction is deflected when the light beam is injected from one medium to another. The common medium is water or glass.

Except for the main light source, all the light in the picture is ambient light. The brightness of ambient light is generally low and there is no clear directionality. There are two kinds of common ambient light: scattered light and reflected light.

1. Scattered light: Different from the scattered light in the illumination light, the scattered light in the illumination light is soft, but it belongs to strong light, which can make the object have a large contrast between light and dark. The scattered light in the ambient light belongs to weak light, which often only affects the place (the dark side of the object) that the main light source can't illuminate.

A common phenomenon of ambient scattered light: walking outdoors to observe your own shadow, the farther away from yourself, the lighter the color. This is because the farther the shadow is, the wider the area is, and the more obvious it is affected by the scattered light around it, so the lighter the color will be.

2. Reflected light: the part of light reflected from the surface of the medium when the light beam strikes the surface of the medium. There are generally two kinds of reflected light: specular reflection and diffuse reflection.

Specular reflection: When the reflecting surface is very smooth, parallel incident light will still reflect in another direction. In daily life, calm water, mirrors and polished metal all produce specular reflection light.

Diffuse reflection light: When the reflecting surface is uneven, parallel incident light will be reflected in all directions. It should be noted that the inhomogeneity mentioned here also includes microstructure. For example, some frosted plastics look smooth, but in fact there are rough particles on the surface, and the light reflected by such plastics is also diffuse light.