Method and apparatus for minimizing ambient illumination effects in a vision system

摘要

Video components attributable to ambient lighting in a stream of digital images of a scene (10) illuminated by both ambient and active sources (16, 14) are eliminated in each image frame, leaving only video components attributable to the active source (14). The spectrum of the active source (14) is encompassed by the ambient source (16), and spectral filtering (48) defines a primary channel comprising video components in a primary spectrum encompassing both active and ambient lighting and a secondary channel comprising video components in a secondary spectrum encompassing only ambient lighting. The pixels of the secondary channel are scaled by a factor correlating the spectral reflectances of the primary and secondary spectra (30), and the scaled secondary channel is subtracted from the primary channel to produce an ambient corrected image (32). The pixels of the ambient corrected image are further scaled to compensate for spectral filter bleeding of the active source into the secondary channel (34).