关键词: 文字篡改, 相机标定, 仿射矩阵

Abstract:

Chinese characters should match certain rules of projection when photoed by digital camera. Meanwhile that will bring projection deviations. In order to detect the information authenticity of the Chinese characters in the digital image, a new estimation algorithm for Chinese characters projection deviation is studied. Based on camera calibration, a new estimation of projection deviation is proposed. And based on Chinese characters’ flat square feature, using Chinese characters model, instead of shooting Chinese characters into the real world, can be coordinated, a set of corresponding point coordinates is extracted, and then the corresponding affine matrix of the image’s homography matrix is obtained. Thus, the deviation value of the reconstruction Chinese character is calculated. If the value obtained is greater than threshold established by experiments before, the Chinese characters in this digital image will be manipulated. Experiments show that this method can detect the rewritten or replaced Chinese characters in the digital image.

Key words: forgeries of Chinese character, camera calibration, homography matrix