Image processing apparatus, method of controlling the same, distance measurement apparatus, and storage medium

1. An image processing apparatus comprising:

a projection unit adapted to project pattern light onto an image capturing target object;

an image capturing unit adapted to capture an image of the image capturing target object on which the pattern light is projected;

a calculation unit adapted to calculate a direction of a line of the pattern light in each predetermined region of the image;

a decision unit adapted to decide an epipolar line based on a relative positional relationship between said projection unit and said image capturing unit;

a determination unit adapted to determine whether an angle made by the direction of the epipolar line and the direction of the line is not more than a predetermined value; and

a detection unit adapted to, upon determining that the angle is not more than the predetermined value, detect the region as a first region, and upon determining that the angle is more than the predetermined value, detect the region as a second region,

wherein said projection unit projects the pattern light having a line component parallel to the epipolar line.

2. The apparatus according to claim 1 , wherein

said detection unit detects

the first region as a 1st-order reflected light region in which the pattern light is reflected only once, and

the second region as a multiple reflected light region in which the pattern light is reflected a plurality of number of times.

3. A distance measurement apparatus comprising:

an image processing apparatus of claim 2 ; and

a measurement unit adapted to measure a distance up to an image capturing target object.

4. The apparatus according to claim 3 , wherein said measurement unit measures the distance up to the image capturing target object for a region detected by a detection unit as a 1st-order reflected light region.

5. The apparatus according to claim 3 , wherein said measurement unit defines a reliability of a distance measurement result for the region detected by said detection unit as the 1st-order reflected light region as a reliability higher than a reliability of a distance measurement result for a region detected by said detection unit as a multiple reflected light region.

6. The apparatus according to claim 1 , wherein said calculation unit calculates the direction of the line using an edge detection filter.

7. The apparatus according to claim 1 , wherein said calculation unit calculates the direction of the line using spatial frequency analysis.

8. A method of controlling an image processing apparatus, comprising:

causing a projection unit to project pattern light onto an image capturing target object;

causing an image capturing unit to capture an image of the image capturing target object on which the pattern light is projected;

calculating a direction of a line of the pattern light in each predetermined region of the image;

deciding an epipolar line based on a relative positional relationship between the projection unit and the image capturing unit;

determining whether an angle made by the direction of the epipolar line and the direction of the line is not more than a predetermined value; and

upon determining that the angle is not more than the predetermined value, detecting the region as a first region, and upon determining that the angle is more than the predetermined value, detecting the region as a second region,

wherein in the causing the projection unit to project the pattern light, the pattern light having a line component parallel to the epipolar line is projected.

9. A computer-readable non-transitory storage medium storing a computer program that causes a computer to execute each step of an image processing apparatus control method of claim 8 .