1. A depth correction apparatus comprising: a clusterer configured to apply clustering to at least one of pixel values and depth values of a plurality of pixels in a calculation range corresponding to a correction target pixel, and to classify the plurality of pixels in the calculation range into a plurality of classes; a first calculator configured to calculate pixel value statistics of the respective classes using pixel values of pixels in the respective classes; a second calculator configured to calculate representative depth values of the respective classes using depth values of pixels in the respective classes; a corrector configured to determine a corresponding class of the correction target pixel based on a pixel value of the correction target pixel and the pixel value statistics of the respective classes, and to apply correction which replaces a depth value of the correction target pixel by a representative depth value of the corresponding class; a third calculator configured to calculate a depth value statistic which represents magnitudes of high-frequency components of depth values of the plurality of pixels in the calculation range; and a switch configured to switch, when the depth value statistic is less than a threshold, processing so as to skip correction of the depth value of the correction target pixel.