Image-processing device, image-processing method, and microscope

An image-processing device comprising:

• a pattern-matching portion that performs pattern matching between a first image and a second image acquired before the first image and that outputs a motion vector between the images and an evaluation value that indicates the accuracy of the motion vector;
• a recursive noise-reduction portion that outputs a noise reduction image, which is the first image to which noise reduction has been applied, and that performs noise reduction in which an image based on the first image and an image based on the previously formed noise reduction image are mixed in accordance with a predetermined recursion amount;
• and
• a controlling portion that controls a recursion amount in the recursive noise-reduction portion on the basis of the motion vector and the evaluation value output by the pattern-matching portion and a gain that is applied to the first image to adjust a brightness thereof;
• wherein the controlling portion performs control so that the recursion amount is greater in a first region than it is in a second region other than the first region, the first region being, in a coordinate plane in which the evaluation value and a motion amount that indicates a magnitude of the motion vector serve as coordinate axes thereof, a region in which the evaluation value is high and the motion amount is low and that is defined by an evaluation-value boundary that divides the evaluation value into two, that is, HIGH and LOW, levels and a motion-amount boundary that divides the motion amount into two, that is, HIGH and LOW, levels.