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Wavelength (Color) Separation


In monochrome imaging the value of each pixel is composed exclusively of shades of gray, varying from black to white. Maximum contrast in imaging is achieved when black pixels (the weakest signal) are measured against white pixels (the strongest signal). Ideal contrast results by passing (highlighting) only relevant wavelengths from the item being inspected and blocking (darkening) the area not needed for inspection. The reverse can work just as well by blocking the wavelengths of the items being inspected and passing the background wavelengths. When contrast is maximized, errors in interpreting results will be minimized. This can greatly improve a system’s accuracy and reliability.




Color cameras may be the first thought when separating items by color, but it can be more efficient and effective to use a monochrome camera with a color bandpass filter. As shown above, to brighten or highlight an items that’s predominantly red, transmission in the red portion of the spectrum must be maximized and all other portions of the spectrum blocked. The reverse can work just as well by using a blue filter to pass blue wavelengths while blocking red.


Choose the Proper Wavelength



Reduce Cost & Lead Time

Being equipped with a large variety of lighting options can be impractical and expensive. Testing with MidOpt filters offers significant savings in time and resources when working toward an optimal lighting solution. Once an appropriate wavelength range has been determined, a bandpass filter is then used to complement the chosen lighting and control potential interference from ambient light.


Control the Variability of Ambient Light

Once appropriate lighting has been chosen, a complementary filter aids in correcting specific problems and in controlling the variability of ambient lighting conditions.


Applications Solutions

Wavelength (Color) Separation


Before: Very low contrast exists between a white date and lot code and a yellow background. After: A BP470 Blue Bandpass Filter placed over the camera lens results in excellent contrast. The BP470 blocks the yellow portion of the spectrum, greatly darkening the background, thus resulting in the white lettering standing out.


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