1. An image processing apparatus comprising: a first edge width correction means for detecting edges in image data, generating first zoom ratio control values according to edge widths of the detected edges, and carrying out an interpolation calculation process on the image data according to the first zoom ratio control values, thereby correcting the edge width; an enlargement processing means for carrying out an enlargement process on the image data with edge widths corrected by the first edge width correction means; a second edge width correction means for detecting edges in the image data enlarged by the enlargement processing means, generating second zoom ratio control values according to edge widths of the detected edges, and carrying out an interpolation calculation process on the enlarged image data according to the second zoom ratio control values, thereby correcting the edge widths; and an edge enhancement means for detecting high frequency components of the image data with edge widths corrected by the second edge width correction means, calculating enhancement values for enhancing the edges according to the detected high frequency components, and adding the enhancement values to the image data with edge widths corrected by the second edge width correction means, thereby enhancing the edges.