Patent ID: 8754846

Claim:
An indication position calculation system calculating an indication position of an indicator, the indication position calculation system comprising: a light-emitting section; an imaging section which is provided in the indicator, acquires an image and successively outputs light-reception information of pixels of the acquired image, wherein one of the pixels having the light-reception information output primarily is disposed on a lower side of the image when the indicator is held in a reference position and another one of the pixels having the light-reception information output last is disposed on an upper side of the image when the indicator is held in a reference position; a determination section which determines whether or not the pixels are effective pixels satisfying a given condition based on the light-reception information without determining whether the pixels are those corresponding to the light-emitting section; and a calculation section which performs position calculations based on identification information of the effective pixels in order to obtain the indication position of the indicator when light received by the effective pixels is included in light emitted from the light-emitting section, the calculation section performing the position calculations based on the identification information of a first effective pixel, the first effective pixel being a first one of the effective pixels determined to satisfy the given condition, wherein the determination section determines whether or not each of the pixels satisfies the given condition and then determines whether or not each of the pixels satisfies a second condition; and wherein the calculation section sets a predetermined area of the image, that is less than an entire area of the image, including the first effective pixel as a determination area, and performs the position calculations based on the identification information of part of the effective pixels included in the determination area, the identification information of the effective pixels included in the determination area and satisfying the second condition being differently weighted from the effective pixels included in the determination area but not satisfying the second condition.