Patent ID: 8290214

Claim:
An indication position calculation system calculating an indication position of an indicator, the indication position calculation system comprising: a light-emitting section; an indicator including an imaging section which acquires an image and outputs light-reception information of a plurality of pixels of the acquired image; a determination section which determines that each of the pixels is a primary effective pixel satisfying a first condition when a value of the light-reception information is larger than a first threshold value, and then determines that the primary effective pixel is a secondary effective pixel satisfying a second condition when the value of the light-reception information is also larger than a second threshold value which is larger than the first threshold value; and a calculation section which performs position calculations based on identification information of the primary effective pixel, wherein the calculation section calculates a representative value representing the primary and secondary effective pixels based on the identification information of the primary and secondary effective pixels and then performs the position calculations based on the representative value, while making a weighing coefficient for the identification information of the secondary effective pixels larger than a weighing coefficient for the identification information of the primary effective pixels in calculation.