1. An image processing apparatus comprising: an image signal correction section configured to perform an image correction process, wherein the image signal correction section performs: a direction determination process of detecting a direction having a minimum pixel value gradient as a pixel value gradient direction in a pixel area including a target pixel; a defect detection process of calculating a Laplacian based on a pixel value of a reference pixel in a minimum gradient direction detected in the direction determination process with respect to the target pixel, and determining presence or absence of a defect of the target pixel; and a defect correction process of performing calculation of a corrected pixel value, which is obtained by applying the pixel value of the reference pixel in the direction detected in the direction determination process, with respect to a target pixel from which a defect has been detected in the defect detection process, wherein the direction determination process is performed using a weighted addition result of a plurality of types of gradient information calculated through a plurality of different gradient detection processes.