Image | |
(Lighting) | 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. |
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. |
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. |
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. |
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