Choose different light source, control and adjust the exposure to the object in the direction of the incident light is the most basic parameters of the machine vision design, it depends on the type of light source and relative to the location of the object is placed, in general there are two basic ways: direct light and diffuse light, and all the other way is extended from these two methods.

Direct light: Incident light basically comes from one direction, the angle is small, it can cast a shadow of the object;

Diffuse light: Incident light coming from multiple or even all directions does not cast a noticeable shadow.

Reflection mode

There are two different reflective properties of light reflected from objects: direct reflection and diffuse reflection.

Direct reflection: the angle of reflection of light equals the angle of incident. Direct reflections can be very useful and can produce very strong glare. Specular reflections should be avoided in most cases.

Diffuse reflection: light falling on an object is diffused in all directions. In most practical cases, diffuse light forms within a range of angles and depends on the angle of the incident light.

A large part of the electromagnetic spectrum of the spectrum is visible to the human eye, electromagnetic radiation in this wavelength range is called visible light, ranging from 400nm to 760nm (some people can observe 380nm-780nm), that is, from purple to red.

Color ring is the sorting of colors in the visible light spectrum, forming a red color connected to the other end of the purple, machine vision applied to the color ring usually includes six different colors, divided into two categories: warm colors and cool colors, warm colors are composed of red tones, while cool colors come from blue tones, usually, the light with opposite color temperature is used to illuminate the image, so the image can reach the highest contrast.

Bright field and dark field

Bright field of view is the most commonly used lighting scheme, which is formed by direct frontal light irradiation, while dark field of view is mainly formed by low angle or backlight lighting, for different detection requirements of projects, different types of lighting are selected. Generally speaking, dard field of view will make the background appear dark while the object under inspection appears bright.