Images all the way.ViSCO Technologies Corporation

Images all the way.ViSCO Technologies Corporation

Optical System Know-how

For image processing inspections, it is extremely important to select cameras, lenses,
and lighting suitable for the inspection details in order to capture images that are easy to inspect.

Types of Cameras, Lenses, and Lighting, and How to Select Them

For image processing inspections, reliably capturing images of the object of inspection is more important than anything, and, like inspection systems, the setup of cameras, lenses, and lighting is essential.
Here, we introduce each representative type as well as how to make selections.


Area sensors and line sensors

Features During image capturing

Area sensors
This is the most commonly used image-capturing method for image processing inspections during which two-dimensional images are captured. The image size is determined by the camera. The objects of inspection are generally stopped, but using strobe lighting makes it possible to capture images of moving objects of inspection.

Line sensors
This image-capturing method is based on the same principle as a scanner or copy machine and involves continuously capturing a one-dimensional image (one line) to synthesize a two-dimensional image. This method is effective for continuously capturing images of objects of inspections bigger than those handled by area sensors. The camera or object of inspection must be moving in one direction.

※You can scroll horizontally.

Monochrome cameras and color cameras

Monochrome cameras With color cameras, because there are limits related to chromatic aberration and lighting colors,
monochrome cameras are used for image processing in an overwhelming number of cases.
Color cameras Color cameras are used to detect color discrepancies and judge color unevenness in objects of inspection.
Because three times the amount of data is required than in the case of grayscale images of monochrome cameras, the image processing equipment must have high performance as well.

Resolution of a 1 CCD color camera


The sort of array shown in the figure on the left is typical for a CCD color filter. The reason there is a lot of green is that human eyes are particularly sensitive to the color. Because the colors R, G, G, and B are assigned to each photodiode to record an image, the resolution falls to 1/4th the number of pixels compared to what it should be. Therefore, for each pixel, the nearby pixel output is used to perform interpolation operations and create RGB.


Telecentric lenses and CCTV lens

■Telecentric lenses

・Because the principal ray is parallel to the optical axis, there is no angle of view.
 →There is no change in the image size.
・Because there is almost no nearby warping,
these lenses are optimal for high-precision dimensional measurement in the depth-of-field direction (the Z axis).
・For cases where the field of view is 50 mm or less

■CCTV lenses

・The image size changes depending on the Working Distance (WD).
・These lenses are suitable for cases where there is a greater emphasis on cost than on precision.
・For cases where the field of view is large (approximately 50 mm or more)

Features of telecentric lenses

■ It is possible to capture images of objects of inspection that have depth from one direction

Example) If looking at the pins of a connector from directly above
Telecentric lens

An image of the tips
of all the pins can be captured
Non-telecentric lens

The sides of the pins are visible,
and there is variation.

■ Even if the distance from the object of inspection to the lens differs, there is no change in the scale factor (lens magnification).

Example) If capturing an image of an object that is at an oblique angle to the lens
Telecentric lens

An orthogonal image is captured
regardless of the WD difference
Non-telecentric lens

There is a sense of perspective due
to the WD difference.


Selection of lighting suitable for an inspection

Because simply changing the lighting pattern can have a major effect on the contrast of an imported image, the key to successful image processing is said to lie in lighting technology. Careful consideration is therefore necessary during the initial lighting selection (the selection of a lighting method, wavelength, and shape suitable for the object of inspection).

Even if an image of an object of inspection is captured from the same direction, simply changing the lighting can change the result this much!

Three selection points

  • Lighting method
    The lighting method is selected based on the shape or unevenness of the object of inspection's front surface as well as what kind of inspection is to be performed.
  • Lighting color (frequency)
    By changing the color of the object of inspection or brightening/darkening the color of the part you want to detect, it is possible to more strongly emphasize the part you want to see when capturing an image.
  • Lighting shape
    The lighting shape is selected based on the size and shape of the object of inspection, the lighting method, and the installation location of the image processing inspection system.

Introduction to our company

As an expert group in the field of visual inspections and image processing inspections, we provide products that continue to lead the industry.

We are an expert group in the field of visual inspections and image processing inspections. We are not just a manufacturer. Instead, we are a visual inspection and image processing inspection system manufacturer that combines knowledge of and experience related to image processing algorithms, optical technology, electronics, and machinery in order to provide comprehensive consulting as a development engineering company.

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