Method for erasing visible watermark of document image

A document and watermark technology, applied in image data processing, image data processing, instruments, etc., can solve problems such as incompatibility, and achieve the effect of improving image restoration quality and erasing effect.

Active Publication Date: 2015-09-09
HEFEI HIGH DIMENSIONAL DATA TECH CO LTD
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  • Abstract
  • Description
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  • Application Information

AI Technical Summary

Problems solved by technology

However, the previous methods for watermark erasure of natural images and video frames are not suitable for document image processing.

Method used

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  • Method for erasing visible watermark of document image
  • Method for erasing visible watermark of document image
  • Method for erasing visible watermark of document image

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Embodiment Construction

[0050] Below, the present invention will be further described in conjunction with the accompanying drawings and specific embodiments.

[0051] Such as figure 1 As shown, a method for erasing visual watermarks of document-like images includes the following steps:

[0052] S1. Perform binary preprocessing on the target image, and then perform boundary refinement and gradient calculation on the obtained binary image to obtain a feature image.

[0053] Here, the target image refers to the normalized image of the document to be repaired with a visible watermark embedded in it. Binarization preprocessing is performed to avoid the inconsistency of the local brightness of the background of the normalized image, and the binary image is further processed Boundary refinement and gradient computation are done to enhance the robustness of the segmentation described below.

[0054] S2. Divide the target image into a watermark area and a non-watermark area (set by human observation). Since...

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Abstract

The present invention provides a method for erasing a visible watermark of a document image. The method comprises: carrying out binaryzation preprocessing on a target image to obtain a feature image; determining watermark areas and non-watermark areas of the target image and the feature image; respectively partitioning the non-watermark areas of the target image and the feature image into a plurality of overlapped blocks and carrying out sampling on each block; constructing a sparse representation model; optimizing the constructed sparse representation model by utilizing a dictionary learning method so as to obtain a compressed target image block dictionary and a feature image block dictionary; and according to the similarity matching degree of the two dictionaries, erasing the visible watermark in the target image by adopting a dictionary similar block erasing algorithm or a local erasing algorithm in a self-adaptive mode. According to the method, the visible watermark of the document image can be effectively erased; moreover, context semantic readability of background texts in an original watermark area can be kept; and the original background texts can be recovered to the greatest degree.

Description

technical field [0001] The invention relates to the technical fields of digital watermarking, image denoising and image restoration, in particular to a method for erasing visible watermarks of document images. Background technique [0002] The main idea of ​​digital watermarking technology is to embed identification information such as serial numbers, codes or icons into digital carriers such as images, audio or video to achieve the purpose of copyright protection. These identification information are called digital watermarks. However, in some special cases, a certain technology is required to erase the watermark of the digital media. For example, the copyright of the watermark has expired, but the product embedded with the watermark still has existence and use value. At this time, the watermark design unit no longer provides technical support and pure scientific research on digital watermark erasure technology; another example, the watermark design unit needs to conduct r...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G06T1/00
Inventor 张卫明田辉郭玉刚胡校成王辉
Owner HEFEI HIGH DIMENSIONAL DATA TECH CO LTD
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