Disclosed herein are an image processing apparatus, a medical imaging apparatus, and an image processing method, which may intuitively and easily set an image processing parameter used to process a medical image to a user-preferred optimal value. The image processing apparatus includes a display unit configured to display a plurality of sample images to which at least one image processing parameter has been variably applied; an input unit configured to receive a selection of one from among the displayed plurality of sample images from a user; and an image processing unit configured to generate a plurality of new sample images to which the at least one image processing parameter has been variably applied based on an image processing parameter to be applied to the selected sample image when the user is not satisfied with the selected sample image.