An object of the present disclosure is to restore a quantization error of an image signal only by expanding the number of bits of a reconstructed image compared to the number of bits of an input image without expanding the number of bits in an image signal processing process. An image display apparatus may include a signal inputter configured to receive an input image signal; an image signal processor configured to perform image processing of the input image signal, to identify a type of image processing by comparing the input image signal and the processed image signal, to obtain restoration information of the processed image signal according to the identified image processing type, and to restore an error of the processed image signal by performing remapping of the processed image signal using the restoration information; and an outputter configured to output the image signal in which the error is restored.