An image recording comprising: an initialization step of generating a predetermined number of search points in a specified region of an image, a filtering step of updating coordinates of a plurality of search points, comparing a characteristic value of the specified region with a characteristic value of each of the search points after updated in the image, assigning to the search points weights determined so as to he increased in proportion to a degree of similarity therebetween, screening the search points according to the weights, calculating a variance and a weighted average of the coordinates of the screened search points, and an image recording determination step of determining, based on the variance and weighted average of the coordinates of the screened search points, and the tracking range, whether or not to record the image, and recording the image if it is determined to record the image.