Liquid crystal display, device and method of modifying image signal

PURPOSE: A liquid crystal display, an image signal correcting device, and an image signal correcting method are provided to prevent image degradation by employing two lookup tables having different grayscale intervals. CONSTITUTION: An image signal correcting unit(61) creates a correction signal based on a first image signal, a second image signal, and a lookup table(50). A data driving unit converts the correction signal into the data voltage. The lookup table includes first and second lookup tables(51,52) and stores a plurality of reference correction signals for first and second reference image signals.