An apparatus and method for improving visibility of an image. The apparatus includes: a lookup table (LUT) generating module generating an LUT having image data in a high illuminance environment corresponding to image data of an input image set therein so as to increase lightness and chroma of the input image according to external illuminance; an image mapping module mapping the image data of the input image into the image data in the high illuminance environment on the basis of the generated LUT; and a local contrast increasing module increasing local contrast of the mapped image data using a parameter for adjusting the local contrast according to the external illuminance.