Below is how your normal color filters work: enter image description here

They let only a single color/wavelength pass. But if this is used say in photography everything would just look very blue with a blue filter, like below: enter image description here

I wanted to ask if any filters exist that Subtract just one color/wavelength, and let all others pass. So a blue "subtractive" filter, let's say, will block off only blue and let all others pass. This is cool because this would preserve the original color constitution of the object, rather than just making everything look like the color of the filter (as we saw above).

So, is this possible? Do such "Subtractive" filters exist? If so, please link.


The type of filter you describe is called a notch filter. They generally work using interferometry i.e. they are designed to produce destructive interference at a single wavelength (or small band of wavelengths). The result is their transmission spectrum has a notch in it at the required wavelength, hence the name.

A quick Google found these examples of notch filter spectra (taken from this document):

Notch filters

  • $\begingroup$ One use for them is laser safety glasses. They filter out only the laser wavelength, leaving the world looking much as it does without them. $\endgroup$
    – mmesser314
    Jul 9 '17 at 5:31

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