US 11,991,325 B2
Image processing apparatus, control method, and storage medium to detect a sheet edge based on marks printed on an adjustment chart and acquired regions of interest images
Hirokazu Tamura, Ibaraki (JP); and Satoshi Ikeda, Tokyo (JP)
Assigned to Canon Kabushiki Kaisha, Tokyo (JP)
Filed by CANON KABUSHIKI KAISHA, Tokyo (JP)
Filed on Jul. 9, 2021, as Appl. No. 17/372,005.
Claims priority of application No. 2020-120865 (JP), filed on Jul. 14, 2020; application No. 2020-171564 (JP), filed on Oct. 9, 2020; and application No. 2021-091615 (JP), filed on May 31, 2021.
Prior Publication US 2022/0021779 A1, Jan. 20, 2022
Int. Cl. H04N 1/00 (2006.01); G06T 7/13 (2017.01); G06T 7/62 (2017.01); H04N 1/08 (2006.01); H04N 1/047 (2006.01)
CPC H04N 1/00748 (2013.01) [G06T 7/13 (2017.01); G06T 7/62 (2017.01); H04N 1/00708 (2013.01); H04N 1/00761 (2013.01); H04N 1/08 (2013.01); G06T 2207/20024 (2013.01)] 17 Claims
OG exemplary drawing
 
1. An image reading apparatus comprising:
a conveyor;
a reader configured to read an image from a sheet conveyed by the conveyor, wherein the sheet is an adjustment chart document having marks printed as part of the image at predetermined positions, and having edges that include a left edge, a right edge, a top edge, and a bottom edge; and
one or more processors configured to perform operations including:
causing the reader to read the image from the sheet to obtain a read image,
acquiring, from the read image and based on the marks printed at the predetermined positions, left and right regions of interest (ROI) images, each including at least a shadow of a respective edge of the sheet, and
after acquiring the left and right ROI images, performing edge detection processing as follows:
extracting, from the left and right ROI images, a plurality of first sheet edge candidates and a plurality of second sheet edge candidates on an opposite edge from the first sheet edge candidates, by performing a binarization process and Hough transform process on data resulting from the binarization process, and
determining a sheet edge pair from among the plurality of first sheet edge candidates and the plurality of second sheet edge candidates.