Method for detecting file scanned image rotating angle and pantographic ratio

Abstract

In current technique, obvious symbol as scaleplate is setup in file in order to raise image recognition of file scanned. But, if copier covers the scaleplate, the scaleplate is out of action. In addition, random noise is added to original file caused by printing, scanning and copying processes, and attached scaleplate is also affected. Thus, recognizing and testing scaleplate is becoming difficult. The disclosed method implants shading composed of dots at bottom of content of file. Specific net dotsimplanted in shading is as scaleplate. Recognizing net dots as scaleplate calculates angle of rotation and scaling of scanned image. Features are: high security and interference killing feature since invisible information of scaleplate.

Description

technical field [0001] The invention belongs to the technical field of image processing, and in particular relates to a method for detecting the rotation angle and scaling ratio of a scanned document image. Background technique [0002] With the rapid expansion of the application field of computer image processing technology, text recognition, image recognition, image restoration, digital watermarking and other processing have become very important technical means, and most of the objects they process are digital images obtained by scanning documents. However, during the document scanning process, due to the influence of subjective or objective factors, the scanned image is usually rotated at a certain angle; on the other hand, if the resolution used when scanning the document is different from the resolution used for printing the original document, It can also cause scaling of the scanned image. In addition, with the development of information hiding technology, people oft...

AI Technical Summary

Problems solved by technology

But there is a big flaw in this method, if the illegal copier covers it with an opaque object, the ruler will lose its effect completely

On the other hand, since printing, scanning, copying and other processes add inestimable random noise to the original document, the scale attached to the scan is also often affected, making the identification and detection of the scale difficult

Repeatedly placing multiple rulers in different places on the document can solve this problem to a certain extent, but it will destroy the visual effect of the document, and as long as the ruler is visible, illegal copiers will always find a way to remove it, and then carry out illegal Copying and Improper Distribution of Documents

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