1. An image processing apparatus for performing image processing on an image to be processed, comprising: a display control unit configured to display on a display unit a plurality of sample images generated by changing one or more image processing parameters to be used when the image processing is performed; a setting unit configured to set, after the plurality of sample images are displayed on the display unit, image processing parameter which are used when the image processing of the image is performed based on a mixing ratio designated by an operator, at which the sample images are mixed; and an image processing unit configured to perform the image processing of the image based on the image processing parameter set by the setting unit.