Inter-reflection detection apparatus and inter-reflection detection method

An inter-reflection detection apparatus, comprising:

• a light source configured to emit light having variable-frequency sinusoidal patterns;
• a camera configured to acquire an image of an object irradiated with the light from the irradiation unit;
• and
• a processor configured to determine a phase at each position in the image, and detect a region in which inter-reflection occurs,
• wherein the processor is configured to:
• for each of a plurality of combinations of low-frequency sinusoidal patterns and high-frequency sinusoidal patterns, determine a phase difference between:
• a first phase acquired by estimation from an image generated by irradiation of the low-frequency sinusoidal pattern;
• and
• a second phase acquired by phase connection from:
• an image generated by irradiation of the high-frequency sinusoidal pattern;
• and the acquired first phase, the phase connection comprising converting an estimated phase from the image generated by the irradiation of the high frequency sinusoid pattern into a continuous variable;
• and
• determine that inter-reflection occurs in a region in which the determined phase difference for any one of the plurality of combinations is equal to or more than a threshold.