Arrangement for improving visual detection of painted areas relative to surrounding material

摘要

Two embodiments for enhancing the detection of a selected area on a surface that may produce specular reflection. In the first embodiment the selected area is coated with a material which will only reflect incident radiation over a narrow band of frequencies and the surface is irradiated with a broadband radiation source that includes the reflectance band of the coating. The irradiated surface is imaged on an imaging device such as a TV camera through a filter selected to reject all but the narrow band of frequencies reflected from the selected area. Further enhancement is provided by comparing the results with those from the same signals filtered by a filter that is the complement of the first. Standard signal processing can then be applied. The second embodiment involves coating the selected surface area with a material possessing the property of radiating energy at one frequency when irradiated by energy at another frequency; irradiating the surface with energy at that other frequency; and viewing the surface with a TV camera through a filter that passes the reradiated energy but blocks the irradiation energy. Complementary filtering could also be applied for further enhancement. Standard signal processing can then be applied to automatically identify the selected area.