Method for geometrically correcting woodcut Tibetan image

Abstract

The invention discloses a method for geometrically correcting a woodcut Tibetan image. A large number of woodcut Tibetan document images are generated in the informatization era, geometric correctionof the woodcut Tibetan document images is the basis of document analysis and character recognition, but a traditional geometric correction method is difficult to implement. Therefore, according to thedeformation characteristics, the thought that the length is shortened and the complexity is reduced is adopted, a segmentation strategy for geometric correction of the woodcut Tibetan document imageis provided, the image is segmented into a plurality of sub-images in the long edge direction, and projection transformation is adopted for correcting all the sub-images. Method of the invention, theproblem that the existing projection method, Hough transformation method, Fourier transformation method, neighbor method and the like which take inclination angle detection as a main thought cannot besuitable due to irregular bending of the Tibetan image of the woodcut plate is solved; and the problem that the existing correction method taking mathematical modeling as a main idea is difficult toapply due to the complexity of deformation of each page and the difference between the pages is solved, and the geometric correction effect of the Tibetan document image of the woodcut board is improved.

Description

technical field [0001] The invention belongs to the field of image processing, in particular to document image correction. Background technique [0002] For the geometric deformation of images, researchers have proposed many correction methods. These methods can be classified into rigid deformation correction methods and non-rigid deformation correction methods. The first type of method considers that the image only has a direction change, and can be corrected by solving the tilt angle and rotating the image. This type of method includes projection method, Hough transform method, Fourier transform method, and nearest neighbor method. The second type of method considers that there is geometric distortion in the image, and maps each pixel position of the deformed image to the undeformed space by constructing a spatial function model between the deformed image and the undeformed image, such as: literature (Haneishi H, Yagihashi Y, Miyake Y. A New Method for Distortion Correct...

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Problems solved by technology

In the second type of method, the correction accuracy directly depends on the accuracy of the mathematical model. However, due to the complex deformation of the Tibetan document image, and each page has different deformations, there is a defect that modeling is difficult.

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