In next step S2, the display control unit 14 reads display color data of the color numbers corresponding to the index values concerning pixels of the read component image data from the color palette and saves display image data obtained by replacing the index values to the display color data of its corresponding color numbers, that is, color component image data, in the temporary memory.

In next step S3, the display control unit 14 reads a display color of the entry of color number 0 (first entry) from read color palette, paints the whole surface of the image display unit 11 with the display color of the entry of color number 0, and thus the background color is set.

In next step S4, the display control unit 14 requests the communication unit 13 to acquire the present set temperature of the air conditioner 20. The communication unit 13 communicates with the air conditioner 20, acquires the present set temperature, and passes it to the display control unit 14. On this occasion, the communication unit 13 also passes information indicating whether the unit of the set temperature is Celsius or Fahrenheit.

In next step S5, the display control unit 14 displays the digit in the tens place (position denoted by reference character 61 in FIG. 3) of the set temperature. For example, if the digit in the tens place is 2, data corresponding to numeral “2” is read from the color component image data obtained by the conversion in step S2 and written in a specific coordinate of the image display unit 11.