A coding scheme is presented in this paper for secretly embedding character information into a dithered multi-level image. This scheme inputs both a monotone image and secret information, which is converted to binary sequences, and it outputs a single dithered image. This image accommodates the character data of about 2K and 3K bytes in dithered bi-level and 3-level image of 256 x 256 pixels, respectively, and it appears as if there would be an ordinary dithered picture. This scheme is available for storing a picture in database or transmitting it on network with secret information.
SUMMARYThis paper reports the effect of printing and scanning on digital watermarks for a hard copy image and investigates the necessary conditions for the watermark to be robust against the printing and scanning process. The effect of the printing and scanning process on the image content is presented first, and that on the Discrete Cosine Transform (DCT) domain is discussed next. Thus, we have necessary conditions for the watermark to be robust and present a sufficient condition to construct robust watermarking. It is realized by decreasing mutual interference between the embedded elements. This will enable us to make image content common to both the electrical nets and the physical nets.
In this paper, we propose how to embed a signature seal to a picture under orthogonal wavelet transform. Three parts of multi-resolution representation are expressed in a vector and are related to each other. The maximum and minimum values among the entries in the vector are obtained and the absolute value of the direrence of them is used f o r controlling to embed the seal. When the seal is needed, we can extract it from the picture. It is clear from the experimental results that the seal does not prevent us from seeing the picture comfortably. Therefore it seems that this method could be used for signing our name in multi-media.
This paper proposes a new duplex modified‐READ (MR) coding scheme for transmitting a facsimile picture on which other information can be embedded. When the vertical mode on the coding‐scanning line is coded, the MR coding is carried out by moving the run‐length of a black or white pel using the bit‐series of an information source to be duplexed. This method offers a facsimile picture which has almost the same quality as its original without increasing the quantity of the MR‐coding, and can transmit the second information without notice by a third person. For example, the second information with 2 k to 14 kbytes can be transmitted with one of the CCITT test documents. This is an answer to conventional facsimile systems which have a lack of secrecy. This method also contributes to double the transmission rate so that transmission lines can be used more efficiently.
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