Image

(Lighting)
Contrast 

The ratio of difference between light and dark as shown on a screen. The change of contrast level refers to 'tone'. High contrast means the difference between light and dark of an subject is clearly appeared.

S/N ratio

The ratio of signal vs noise.
A value indicating the strength of the desired signal level, in comparison to unnecessary background noise. The greater differences the better results.

Binary

A technique by which to obtain the brightness of pixels and output white. When the level of brightness is greater than a specified value or when the level is lower than a specified value. By this technique, however, the intermediate tone section is divided into white or black. While the image with extremely emphasized features can be obtained, there is a disadvantage that intermediate tones cannot be represented.

Threshold value

Generally, it refers to the value of the boundary for dividing an area, but in image processing, it means the reference value to divide a binary image whether it is black or white. When creating a binary image from a multi-level image, it is necessary to set at which gray level two values of white and black will be distinguished.

LED

Spectrum

Energy irradiation propagated as an electromagnetic wave arranged in the order of its wavelength. The electromagnetic wave is divided into radio waves, micro waves, infrared rays, visible light, ultraviolet rays, X-rays, gamma rays, cosmic rays, etc. according to its wavelength. Among these, especially the wavelength range (380-780nm) that when the human eye can feel and produces brightness is called light. When only light of a specific wavelength is extracted, the light is seen as color perceived by the human eye. Rotating through the visible light spectrum gives the impression of changing colors.

Peak wavelength

The maximum wavelength of light radiated from a light regardless of its strength.

Chromaticity diagram

Two-dimensional coordinates of x and y which represents tone (hue and saturation). The tone is the same even if the brightness differs. The color is represented by the same chromaticity coordinate (x, y). In a chromaticity diagram, white light is represented by a mixture of the three primary colors. The ratio is 1:1:1. For example true white, shows that the coordinates of x and y, have an ideal color at a position of x = 0.33 and y = 0.33. The diagram is prepared assuming that the total of the ratio of the three-primary colors is 1. Thus, when x = 0.33, and y = 0.33 the component blue (z) automatically becomes 0.33a and turns into white.

Color temperature

A value used to represent the light intensity of a particular color. The color temperature is represented by checking the color of a light emitted when a complete black object (that absorbs all external light) changes to a high temperature and it emits its own light due to the high temperature. The color usually changes from red to white and to blue. The color temperature is represented by the absolute temperature of the complete black object of the same color by using the unit K (Kelvin). The higher the color temperature of a light is, the bluer the light this it emitted from the black object. Due to the nature of the wavelength of the emitted light. The lower the color temperature the redder the light is because of a longer wave length of emitted light.

Luminous intensity distribution (characteristic)

The orientation dependency of the LED fs brightness intensity is represented by a relative value. When an angle is 50% of the peak value, the brightness intensity is called the orientation angle half-value width and is used as a guide to represent the sharpness of the orientation characteristic.

Optics

Regular reflected light

Light irradiates onto a mirror-like surface and is reflected to produce an image. It is called spectrum light reflection.

Regular transmitted light

Light irradiates on to such an object like transparent glass and is transmitted unchanged. It is called the positive light transmission

Scattering light

A light irradiated onto white paper scatters in every direction. A face can be reflected on a mirror but cannot on paper. You cannot see an image behind the object unlike transparent glass, either. However, light is scattered and a vague bright image can be seen because light is scattered in every direction. It is called the scattered light that is, scattering reflected light or scattering light transmission.

Diffused light

The light of a source diffused and irradiated in various directions is called diffuse light. The same is true to the light of a strong source with a high orientation and is diffused with a diffusion plate. The light has a great variation of irradiation angles with regard to a subject.

Parallel light

A parallel beam refers to a light where the beam travels in parallel to any extent without spreading. The light from a distant star irradiated to the Earth is particularly close to being a parallel beam. That is to say, light with a small variation in the irradiation angle in relation to a subject.

Polarized light

Light with a specific optical wave oscillation orientation.

Polarizing filter

A filter having the property of transmitting only an optical wave, with a specific oscillation orientation.

Polarizing plate

A plate or film with a limited direction of optical wave oscillation or an object serving the function.

Disturbance light

Light other than illumination used for imaging and having influence over the desired results.

Lens

Chromatic aberration

How light bend within a lens depends on the wavelength of the light. The light transmitted through a lens is scattered into the seven-color spectrum, like an rainbow and forms an image at a certain point. That is, the formation of the images position differs for each color.

Depth of field

Depth of field refers to the distance range where an object is focused clearly. Depth of field varies diversely depending on the size of aperture, distance of the focused subject and the lens focal distance. Depth of field has the following properties:
1) The greater the F number is, the greater the depth of field.
2) The shorter the focal distance is, the greater the depth of focus.
3) The farther the distance to the subject, the greater the field of depth.

Lighting Method

Bright field lighting

An illumination and observation system for observing the positive light reflection or positive light transmission hence, direct light.

Dark field lighting

An illumination and observation system for observing scattered light.

LWD

Abbreviation for Light Working Distance. The distance from a light source to an object. (In optics, Lens Working Distance is typically used.)

WD

Abbreviation for Working Distance. Distance from a lens to an object.

Power Supply

Digital intensity control
(duty control)

Intensity control of PD series type. Intensity is controlled by changing the pulse to ON duty (ratio of the lighting time in one pulse). 8-bit control provides 256-stage linear intensity. When a high-speed shutter is used, care must be taken regarding frequency interference.

Analog dimming (voltage control)

Intensity control of PSB series type. Intensity is adjusted by setting the voltage. The current varies with light. Its constant lighting does not produce frequency interference even when a high-speed shutter lens is used.

Current control

Intensity control of PLV series type. Intensity is adjusted by setting the current. The voltage varies with illumination. Constant lightening does not generate frequency interference even when a high-speed shutter lens is used.

External control of dimming

Illumination dimming is controlled by sending a signal to the illumination power supply externally from a PLC, personal computer or another device

External control of lightening (ON/OFF)

Illumination lighting (ON/OFF) is controlled by sending a signal to the illumination power supply externally from a PLC, personal computer or other device.

Measurement

Illuminance

Representational of the luminous amount of the surface of an object receives from a light source. It is given by the illumination of light (lux) fallen on a subject per unit area. The unit is lx(lux). Illumination (lx) = light flux (lm:lumen)/area (m2)

Luminance

The Luminous intensity represents the brightness of an object, and on the other hand, the brightness corresponds to the brightness of a light source taking into consideration its direction. The distance is not related to the measurement. The unit is cd (candelas)/m2.

Relative luminous efficiency
(of a standard observer),
Standard relative luminosity

The International Commission on Illumination (CIE) have set a standard on the wavelengths that can be perceived by the normal human eye. The spectrum luminous efficiency is dependant on this standard

CCD luminance

The brightness is represented by the intensity of a light source and the luminosity of a light source can be distinguished by the difference of the lightness/darkness. The CCD brightness assumes by a relative unit how much brightness is felt when a human eye is substituted by a CCD camera with a sensitivity characteristic different from that of the human eye. On the other hand, the cameras setting of the CCD and optical system used for measurement have influence over the absolute value.