Patent ID: 7113544

Claim:
A motion detecting device comprising: a threshold value control circuit that determines, with respect to a first pixel for which detection of motion is going to be performed, a threshold value based on a difference of image data between a second pixel and a third pixel that are arranged in lines immediately above and below a line in which the first pixel is arranged and that are adjacent to the first pixel; and a motion detecting circuit that checks whether motion is present at the first pixel or not, based on results obtained by comparing a difference, between two fields, of image data of each of the first, second, and third pixels with the threshold value, wherein the threshold value control circuit sets the threshold value in such a way that the threshold value becomes smaller as the absolute value of the difference between the image data of the second and third pixels becomes smaller and that the threshold value becomes greater as the absolute value of the difference between the image data of the second and third pixels becomes greater, wherein, as image data constituting one field after another, image data of pixels arranged in even-numbered lines and image data of pixels arranged in odd-numbered lines is fed in alternately, and whether a subject is in motion or not is checked at each of pixels in those lines to which no image data is allotted in a given field, and wherein, to check whether the subject is in motion or not, a difference, between two fields, of image data of each of a plurality of pixels adjacent to the first pixel, including the first, second, and third pixels and having the first pixel at a center, is compared with the threshold value determined individually for those pixels, and whether motion is present at the first pixel or not is checked based on a plurality of results that the comparison yields.