Patent ID: 10701352

Abstract:
An image monitoring device includes a maximum value and minimum value calculator, a small-luminance-difference determiner, a small-luminance-difference-block counter, and a dirt adherence determiner. The maximum value and minimum value calculator calculates, for each of a plurality of blocks set in one frame of a video signal obtained through a lens, a maximum luminance value and a minimum luminance value of a plurality of pixels forming each of the plurality of blocks. The small-luminance-difference determiner determines whether or not each of the blocks has a small luminance difference, by comparing a difference between the maximum luminance value and the minimum luminance value with a first threshold. The small-luminance-difference-block counter counts a number of blocks having the small luminance difference in the one frame. The dirt adherence determiner determines whether or not dirt is adherent to the lens, based on the number of blocks having the small luminance difference.