A device includes a first isolated-point candidate detection section calculates a parameter value used for detecting an isolated-point candidate from a near-field region of a target pixel of a color image signal, a color-space conversion section combines a plurality of signals constituting the color image signal together, and converts the combined signals into a plurality of color signals on defined color space, a second isolated-point candidate detection section calculates a parameter value used for detecting an isolated-point candidate from a near-field region of a target pixel of the converted color signal, and an isolated-point degree determination section determines an isolated-point degree on the basis of parameter values calculated by the isolated-point candidate detection sections.