Imaging apparatus and method of optical-black clamping

摘要

An imaging apparatus has a solid-state image sensing device having an imaging area divided into left and right sub-imaging areas, a first optical-black (OB) area and a second OB area being provided at both edges of the imaging area in the horizontal direction. First video signals are extracted from monitoring areas in the sub-imaging areas close to the border between the sub-imaging areas. Optical-black clamping is applied to second video signals output from the sub-imaging areas by subtracting a first OB signal indicating an OB level in the first OB area from the second video signal output from one of the sub-imaging area and subtracting a second OB signal indicating an OB level in the second OB area from the second video signal output from the other of the sub-imaging areas. Detected first in the optical-black clamping is a level difference between the extracted first video signals. Calculated next is an adjusting value per row of pixels, that provides the smallest level difference per row of pixels in the imaging area based on the detected level difference. The first OB signal is subtracted from one of the second video signals and the second OB signal is subtracted from the other second video signal, thus outputting an optical-black-clamped video signal. Video-signal levels are adjusted by multiplying the optical-black-clamped video signal by the adjusting value.