US 11,055,564 B2
Image processing apparatus, image processing method, and storage medium
Kazuhiro Yahata, Kunitachi (JP)
Assigned to Canon Kabushiki Kaisha, Tokyo (JP)
Filed by CANON KABUSHIKI KAISHA, Tokyo (JP)
Filed on Nov. 27, 2018, as Appl. No. 16/201,740.
Claims priority of application No. JP2017-231082 (JP), filed on Nov. 30, 2017.
Prior Publication US 2019/0164008 A1, May 30, 2019
Int. Cl. G06K 9/62 (2006.01); G06T 5/20 (2006.01); G06T 5/00 (2006.01)
CPC G06K 9/6214 (2013.01) [G06K 9/6215 (2013.01); G06T 5/002 (2013.01); G06T 5/20 (2013.01); G06T 2207/20076 (2013.01)] 17 Claims
OG exemplary drawing
 
1. An image processing apparatus comprising:
a processor coupled to a memory to perform operations including:
setting a target patch in an input image, wherein the set target patch includes a number of pixels corresponding to characteristics of a target pixel in the input image and a pixel group in a vicinity of the target pixel as the target patch relative to the target pixel,
detecting a plurality of similar patches which are similar to the target patch set in the input image, wherein the plurality of similar patches includes pixels,
calculating, as a matrix calculation, a covariance matrix representing correlation between pixels based on the detected plurality of similar patches,
calculating a plurality of eigenvalues and a plurality of eigenvectors of the calculated covariance matrix,
obtaining a noise amount in the input image,
deriving a correction matrix that is different from the calculated covariance matrix and, in a case where eigenvectors corresponding to eigenvalues which are larger than a threshold value, the derived correction matrix is based on the plurality of eigenvalues, the plurality of eigenvectors, the noise amount, a number of detected similar patches, the eigenvectors corresponding to the eigenvalues which are larger than the threshold value, and, in a case of correcting eigenvalues smaller than the threshold value, the corrected eigenvalues and eigenvectors corresponding to the corrected eigenvalues,
correcting, as a patch correction, values of pixels in at least one of the plurality of similar patches based on the derived correction matrix, and
generating an output image by combining the similar patches having pixels values corrected by the patch correction,
wherein the threshold value is set in accordance with the noise amount in the plurality of eigenvalues and the number of pixels included in the plurality of similar patches, and
wherein deriving includes correcting eigenvalues smaller than the threshold value and deriving the correction matrix based on the corrected eigenvalues and eigenvectors corresponding to the corrected eigenvalues.