To harmonize the texture of a display surface of an image display system with an environment.

An A/D converter 216 is connected to a video camera 120 and converts the analog signal of the video camera 120 into a digital signal. The video camera 120 is fixed to a display device 100 to face ahead of the display device 100, and functions as a light source information acquiring means of acquiring light source information on the circumference of the display device 100. The output signal of the video camera 120 is input to a CPU 202. The CPU 202 calculates the distribution of lightness of a photographed image, and sets a light source in a method of assuming that a light source is located at a position corresponding to the lightest position. When an image etc., is generated, the CPU 202, a system memory 204, a video display processor 214, and a graphic memory 222 cooperate to function as an image processing means of generating a luminance image obtained by adding light and shade, reflected light, etc., corresponding to the light source to the image.