Operation input device, operation input method, and computer-readable recording medium

An operation input method comprising the steps of:

• radiating infrared;
• detecting infrared to capture an image;
• calculating, in the image, a luminance difference between a first luminance of a first area irradiated with the infrared and a second luminance of a plurality of second areas that are areas not irradiated with the infrared;
• adjusting an irradiation intensity of the infrared to be radiated so that the luminance difference becomes a predetermined target value;
• detecting a shape of an indication object from the image;
• determining an operation by the indication object from the shape;
• and
• instructing a device to perform a function corresponding to the operation.

A program for causing a computer provided in an operation input device to perform:

• a luminance calculating circuit configured to calculate, in a captured image which is an image in which infrared is detected and captured by a camera unit, a luminance difference between a first luminance of a first area irradiated with the infrared by an infrared irradiation device and a second luminance of a plurality of second areas that are not irradiated with the infrared by the infrared irradiation device;
• an infrared control circuit configured to adjust an irradiation intensity of the infrared to be radiated from the infrared irradiation device to cause the luminance difference calculated by the luminance calculating circuit to become a predetermined target value;
• an image processing circuit configured to detect a shape of an indication object from the captured image;
• a determination circuit configured to determine an operation by the indication object from the shape detected by the image processing circuit;
• and
• a command circuit configured to control a device to perform a function corresponding to the operation determined by the determination circuit.