1. An image processing apparatus comprising: a signal processing unit that executes pixel value compensation, wherein the signal processing unit inputs image data in an RGBW arrangement that has each color pixel of R, G, and B and a white (W) pixel that passes through almost all wavelength light of each wavelength of the R, G, and B, and wherein the signal processing unit interpolates the W pixel at a position of an attention pixel that is a compensation target, and at a position of a reference pixel which has the same color as the attention pixel within a reference area, in a pixel value compensation processing of a color pixel, calculates smoothing weight based on each pixel value of the interpolation W pixel, and thus calculates a compensation pixel value of the attention pixel by executing smoothing processing to which the calculated smoothing weight is applied.