Inspection apparatus, inspection method, and computer-readable storage medium

1. An inspection apparatus configured to perform position adjustment between a reference image and a target image of a printed document to inspect the printed document, the inspection apparatus comprising:

an extraction unit configured to extract a feature point of each of the reference image and the target image used for the position adjustment;

an acquisition unit configured to acquire an image in a band region of a predetermined size from each of the reference image and the target image;

a position adjustment unit configured to perform a first position adjustment on the reference image and the target image in the band region, using each feature point in the band region extracted by the extraction unit;

a first determination unit configured to compare the reference image and the target image after the first position adjustment and determine whether there is a difference between the reference image and the target image after the first position adjustment; and

a second determination unit configured to determine whether there is a feature point for the first position adjustment in a region adjacent to the band region, in a case where the first determination unit determines that there is a difference between the reference image and the target image in the band region after the first position adjustment,

wherein in a case where the second determination unit determines that there is no feature point for the first position adjustment in the region adjacent to the band region, the position adjustment unit performs a second position adjustment of the reference image and the target image after the first position adjustment using a feature point for the first position adjustment in the band region and additional patch information in the region adjacent to the band region, and

wherein the determination unit determines whether there is a difference between the reference image and the target image after the second position adjustment, and

wherein in a case where the second determination unit determines that there is a feature point for the first position adjustment in the region adjacent to the band region, the position adjustment unit does not perform the second position adjustment.

2. The inspection apparatus according to claim 1 , further comprising:

a reference patch extraction unit configured to extract a reference patch from the reference image based on a size of a feature amount of the feature point extracted from the reference image; and

a specification unit configured to specify a target patch corresponding to the reference patch from the target image,

wherein the position adjustment unit compares the reference patch and the target patch to obtain a shift amount between the reference patch and the target patch to perform the position adjustment based on the obtained shift amount.

3. An inspection method for performing position adjustment between a reference image and a target image of a printed document and performing inspection of the printed document, the method comprising:

extracting a feature point of each of the reference image and the target image for the position adjustment;

acquiring an image in a band region of a predetermined size from each of the reference image and the target image;

performing a first position adjustment using each feature point in the extracted band region on the reference image and the target image in the band region; and

performing a first determination for comparing the reference image and the target image after the first position adjustment to determine whether there is a difference between the reference image and the target image after the first position adjustment,

wherein in a case where it is determined by the first determining that there is a difference between the reference image and the target image in the band region after the first position adjustment, the method further comprises;

performing a second determination for determining whether there is a feature point for the first position adjustment in a region adjacent to the band region;

performing a second position adjustment of the reference image and the target image after the first position adjustment, in a case where it is determined by the second determining that there is no feature point for the first position adjustment in the region adjacent to the band region, using a feature point for the first position adjustment in the band region and additional patch information in the region adjacent to the band region; and

performing a third determination for determining whether there is a difference between the reference image and the target image after the second position adjustment,

wherein in a case where it is determined by the second determining that there is a feature point for the first position adjustment in the region adjacent to the band region, the second position adjustment is not performed.

4. The inspection method according to claim 3 , further comprising:

extracting a reference patch from the reference image based on a size of a feature amount of the feature point extracted from the reference image;

specifying a target patch corresponding to the reference patch from the target image; and

comparing the reference patch and the target patch to obtain a shift amount between the reference patch and the target patch to perform the position adjustment based on the obtained shift amount, in performing the position adjustment.

5. A non-statutory computer-readable storage medium for storing a program to cause a computer to perform position adjustment of a reference image and a target image of a printed document to perform inspection of the printed document, the method comprising:

extracting a feature point of each of the reference image and the target image for the position adjustment;

acquiring an image in a band region of a predetermined size from each of the reference image and the target image;

performing a first position adjustment using each feature point in the extracted band region on the reference image and the target image in the band region; and

performing a first determination for comparing the reference image and the target image after the first position adjustment to determine whether there is a difference between the reference image and the target image after the first position adjustment,

wherein in a case where it is determined by the first determining that there is a difference between the reference image and the target image in the band region after the first position adjustment, the method further comprises;

performing a second determination for determining whether there is a feature point for the first position adjustment in a region adjacent to the band region;

performing a second position adjustment of the reference image and the target image after the first position adjustment, in a case where it is determined by the second determining that there is no feature point for the first position adjustment in the region adjacent to the band region, using a feature point for the first position adjustment in the band region and additional patch information in the region adjacent to the band region; and

performing a third determination for determining whether there is a difference between the reference image and the target image after the second position adjustment,

wherein in a case where it is determined by the second determining that there is a feature point for the first position adjustment in the region adjacent to the band region, the second position adjustment is not performed.