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Notch Filters

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We have special notch filters designed to remove the shared information between the camera color channels.  Currently, these filters are only available in 30mm or 58mm sizes.

Digital color cameras see color by filtering the light through a Color Filter Array (CFA) that is photolithography printed over the monochrome photodiode.  

Surface of the camera sensor 

The color dyes used for the CFA overlap each other so at some light frequencies, blue and green will both see light and green and red will both see light.

Typical camera sensor response to various light frequencies

The frequency response is affected by things like White Balance (WB) settings and various other processes in the camera, but holding those things constant, we can see the camera's response to light.  From out Vision FAQ remember that humans can see, for the most part, from 400nm blue to about 700nm red.  Each wavelength has a slightly different color.

Sometimes, it is desirable to remove the shared frequencies between the RGB color channels.  We have designed two special filters to remove most of the RGB color channel overlap - one for the Blue-Green overlap and one for the Green-Red overlap.



Applying the Blue-Green filter to a typical camera, will result in the following response.

Adding on the Green-Red notch filter, we get







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Last modified: June 18, 2015