Markany Inc.

Jong Won Kim

Jong Uk Choi

Han Ho Lee

Jung Suck Cho

Simultaneously with a robust watermark and fragile watermark or semi-watermark is embedded into conventional securities, etc., such as gift coupon, various kinds of ticket, coupon, electronic stamp, bond & debenture, note, stock certificate, lottery, paper money, check, etc. and various kinds of public documents including certificates, etc. requiring confirmation and authentication (hereinafter, referred to as 'securities, etc.') in the form of digital file. Such watermark-embedded securities, etc. are conveniently issued on-line and are printed out in the form of paper through a printer. The printed securities, etc. are used off-line and are authenticated by determining the forgery or alternation by means of photocopy, etc. through the detection of the embedded watermark.

Apparatus and method for issuing and authenticating securities, etc. using digital watermarking

The present invention relates to a method for embedding a watermark into a black and white or color digital image [D(x)]. Basically the inventive method comprises the steps of transforming the digital image using a wavelet transform [WC(y)], transforming a watermark using discrete cosine transform (DCT), integrating the wavelet-transformed digital image with the DCT-transformed watermark [DW(x)+WC(y)] to insert the watermark into the image, and generating the watermarked image using inverse wavelet transform [D(x)']. For color images, RGB mode is converted into YIQ mode using a conversion matrix and the wavelet transform is applied to the Y-, I-, Q-values. This inventive digital watermarking of a color image is found to be highly robust against lossy compression and other image processing operations, compared to conventionally known methods which are known to be unsuitable for watermarking color images.

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Taejeon, South Korea

Jong Won Kim