Light filtering is a typical need in machine vision applications. Together with LED illuminators, filters can improve image contrast by blocking unwanted light and increase the accuracy and repeatability of the vision system. Ambient light is very frequently causing errors in imaging systems due to unwanted reflections off the surface of the parts being measured. In these cases, a band pass or long pass filter that matches the emission wavelength of the illuminator is usually integrated in front of the imaging lens: this way, only the light coming from the illuminator is collected while the rest of the spectrum is cut out. Furthermore, many machine vision applications require monochrome illumination in order to enhance or suppress particular object features: under these conditions, only the features with a certain color are imaged and inspected.