An image processing apparatus includes: a pixel difference calculator for calculating a difference value between each first pixel of a previous image and a second pixel of a present image and at a position corresponding to said each first pixel, and outputting a plurality of pixel differences; a counter counting a number of positive pixel differences and a number of negative pixel differences in the pixel differences of a sampling window; a motion level determining unit calculating a motion level of a pixel in the sampling window according to the numbers of the positive and negative pixel differences; a blending value determining unit determining a blending value according to the motion level; and an output unit adding together weights of the present and previous images according to the blending value to generate and output an output image. An image processing method is also disclosed.