A computer readable medium storing a program that, when executed by a computer, is operable to control an optical display device having an optical modulator that has a plurality of pixels whose optical propagation characteristics can be controlled independently and a luminance adjusting element that has a plurality of pixels whose optical propagation characteristics can be controlled independently, the pixels in the optical modulator and the pixels in the luminance adjusting element being arranged to optically correspond at m:n, m and n being integers and m<n or n>m, the device modulating light from a light source through the optical modulator and the luminance adjusting element and displaying an image,
- the program enabling the computer to carry out processing comprising:
- calculating an average value or weighted average value of color component values on a color-basis in pixel values corresponding to the n pixels based on the display image data;
- selecting a luminance value corresponding to each of the pixels in the optical modulator among luminance component values in the pixel values corresponding to the n pixels based on the display image data;
- determining an optical propagation characteristic of each of the pixels in the optical modulator based on a result of calculation by the average value calculating and a result of selection by the luminance selecting;
- and
- determining a control value for each of the pixels in the optical modulator based on the optical propagation characteristics determined by the optical propagation characteristic determining.