1. An image processing device comprising: an edge detection unit for detecting an edge using an input image signal consisting of a plurality of color signals including a color signal having a different appearance frequency from another color signal, or a predominant color signal, which is a color signal with a highest appearance frequency, contained in the input image signal; a sub-color parameter calculation unit for calculating, with respect to a sub-color signal which is a color signal other than the predominant color signal in the plurality of color signals, from a pixel of interest and neighboring pixels of a same color as the pixel of interest, a sub-color parameter value related to a degree of isolated point of the pixel of interest; and a sub-color isolated point correction unit for correcting the pixel of interest based on the sub-color parameter value calculated by the sub-color parameter calculation unit and information of the edge detected by the edge detection unit.