Depth measurement apparatus and controlling method thereof

A depth measurement apparatus comprising:

• an image signal acquisition unit configured to acquire a first image signal from a first viewpoint and a second image signal from a second viewpoint;
• a correlation value acquisition unit configured to calculate, with respect to a plurality of shift amounts, a correlation value between the first image signal in a depth detection region and the second image signal in a region obtained by shifting the depth detection region;
• a provisional shift amount acquisition unit configured to acquire a plurality of provisional shift amounts on the basis of the correlation value;
• an image restoration unit configured to subject, for each of the plurality of provisional shift amounts, at least one of the first image signal and the second image signal to image restoration using an image restoration filter corresponding to each of the plurality of provisional shift amounts;
• a contrast analysis unit configured to analyze a contrast change resulting from image restoration processing by the image restoration unit;
• and
• a depth determination unit configured to determine depths with respect to a plurality of pixels in the depth detection region on the basis of a result of contrast analysis by the contrast analysis unit, wherein
• the provisional shift amount acquisition unit determines a first shift amount at which an extreme value of the correlation value is given, divides a first range, which is a range of a predetermined shift amount including the first shift amount, into a plurality of second ranges in order to acquire a provisional shift amount for each of the second ranges.