Patent ID: 8558854

Claim:
An image recognition method comprising: a first step of acquiring n-th received light data at light receiving elements arranged in a matrix form on a light receiving surface; a second step of acquiring (n+1)-th received light data at the light receiving elements; a third step of calculating differential data resulting from subtraction of the n-th received light data acquired from the (n+1)-th received light data acquired; and a fourth step of carrying out image recognition based on the differential data, wherein a peak value and a bottom value occur in the differential data and the carrying out of the image recognition comprises one of: setting as image information for the peak value a first binary value when the peak value is greater than a threshold value and setting as image information for the peak value a second binary value when the peak value is less than the threshold value, and setting as image information for the bottom value a first binary value when the bottom value is less than the threshold value and setting as image information for the bottom value a second binary value when the bottom value is greater than the threshold value; and wherein, the threshold value is adjusted by an amount that is based on a distance between a location corresponding to the peak value and a location corresponding to the bottom value.