Patent ID: 9686474
Date: 2017-06-20
CPC Classifications: G02B,G03B,H04N

Claim:
1. A method of frequency prefiltering image data, the method comprising: receiving, via an input of an optical filter, an electronic control signal usable to control the optical filter, the optical filter having an adjustable opacity and being disposed external to a camera housing of a video camera in an optical path of the video camera; and varying the opacity of the optical filter based at least on the electronic control signal so that an amount of light incident on an image sensor within the camera housing varies during an image frame period for the image sensor, wherein the image frame period has a duration corresponding to an image frame frequency for the image sensor, and the opacity of the optical filter is varied during the image frame period so that object motion having a frequency above one half of the image frame frequency is filtered from image data generated by the image sensor, the image data corresponding to the light incident on the image sensor during the image frame period, wherein the opacity of the optical filter is varied during the image frame period so that a peak in transmissivity of the optical filter occurs mid-way during the image frame period.