1. An image processing apparatus comprising: a min-max pixel difference value computing unit configured to compute a min-max pixel difference value defined as a difference between a maximum pixel value and a minimum pixel value in an image portion for feature value computation that includes a target pixel selected from among pixels forming an input image and a number of neighbor pixels; a maximum adjacent pixel difference value computing unit configured to compute a maximum adjacent pixel difference value defined as a maximum value among the difference values between adjacent pixels in the image portion for feature value computation; an image change feature value computing unit configured to compute an image change feature value corresponding to a suddenness of image change in the image portion for feature value computation at least in part on the basis of the min-max pixel difference value and the maximum adjacent pixel difference value; a filter coefficient computing unit configured to compute filter coefficients at least in part on the basis of the image change feature value; and a sharpen filter configured to accept, as input, pixels forming an image portion for filter processing that include the same target pixel as the image portion for feature value computation and a number of neighbor pixels, and to compute an output pixel value for the target pixel in the image portion for filter processing by using filter coefficients corresponding to the image portion for feature value computation.