1. An image processing apparatus, comprising: a correcting unit for correcting a signal value of image data corresponding to pixels aligned in a first alignment direction and in a second alignment direction that is perpendicular to the first alignment direction, the correcting unit performing a correction processing for intensifying an edge of image data; a detection unit for detecting a direction of the edge of the image data with respect to a predetermined pixel of the image data based on a luminance value of the predetermined pixel and a luminance value of pixels surrounding the predetermined pixel; a calculating unit for calculating a variation amount indicating a magnitude of change in the luminance value in the direction of the edge based on the luminance value of the predetermined pixel and the luminance value of the pixels surrounding the predetermined pixel; and a setting unit for setting an intensity of the correction processing based on correction intensity which is predetermined based on sharpness varying depending on an alignment direction of the pixels, according to the calculated variation amount in the edge direction of the image data detected by the detection unit, wherein when sharpness of the image data in the first alignment direction is higher than sharpness of the image data in the second alignment direction, the setting unit sets the correction intensity such that the correction intensity for the image data having the variation amount in the first alignment direction is set to be stronger than the correction intensity for the image data having the variation amount in the second alignment direction, wherein thresholds of the variation amount define the predetermined correction intensity, such that correction intensity for the image data having the variation amount in the first alignment direction having higher sharpness is set to be stronger than correction intensity for the image data having the variation amount in the second alignment direction having lower sharpness, and wherein the thresholds are values in a range between a maximum variation amount of the first alignment direction of pixels and a maximum variation amount of the second alignment direction of pixels, with respect to the predetermined pixel of the image data.