Patent Document ID: 9881228
Application ID: 14965548

Base Claim:
1. A method for removing a mark in a document image, the method comprising: extracting connected components from a binary image corresponding to the document image; clustering the connected components based on grayscale features of the connected components to obtain one clustering center; searching, within numerical ranges of a clustering radius R from the clustering center and a grayscale threshold T, for a combination (R, T) which causes an evaluation value based on the grayscale features of the connected components to be higher than a first evaluation threshold; and removing the mark in the document image based on the grayscale threshold in the combination; wherein the grayscale features of the connected components comprise: a minimum one of grayscale values of pixels in the document image, which correspond to all black pixels in each of connected components; wherein the removing the mark in the document image based on the grayscale threshold in the combination comprises: removing the connected components, the grayscale features of which are greater than the grayscale threshold, as the mark in the document image.

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Claim 2:
2. The method according to claim 1 , wherein the connected components are clustered further based on intrinsic features of the connected components to obtain the one clustering center; wherein the intrinsic features of the connected components comprise at least one of: a number of black pixels in each of the connected components, a ratio of the number of the black pixels in the connected component to a number of pixels in a bounding box of the connected component, and an aspect ratio of the bounding box of the connected component, in the binary image.