Showing papers on "Watermark published in 1995"

Watermarking digital images for copyright protection

Abstract: A watermark is all invisible mark placed on an image that can only be detected when the image is compared with the original. This mark is designed to identify both the source of a document as well as its intended recipient. This paper discusses various techniques for embedding such marks in grey scale and colour digital images. It begins specifying the requirements that an effective image watermarking scheme must possess, followed by a review of current and novel techniques based on image transforms.

Method and apparatus for the addition and removal of digital watermarks in a hierarchical image storage and retrieval system.

Abstract: An image processing technique is described in the context of a hierarchical image storage and retrieval system. The method allows for the controlled addition and removal of digital watermarks from selected image components in the hierarchy. The method adds a digital watermark in a selected image resolution component and the means to remove it in an additional image component termed the watermark removal component. The method employs the encryption of the watermark removal component, and decryption with a special key, or password during authorized retrieval. This technique allows users of a distributed system the convenience of providing the entire image hierarchy on a single storage medium permitting images containing watermarks to be accessed without restriction for browsing and proofing, while the watermark removal requires knowledge and us of a controlled code.

Marking of optical disc for customized identification

Abstract: Techniques for marking of optical data discs with a unique characteristic marking for purposes of identification and verification of authenticity. The marking, referred to as a 'watermark' can be a name, logo, design, picture or other pattern which is applied within the structure of the data disc. The watermark is applied to the master disc, and will therefore be reproduced in all production replica discs through the use of standard stamper and replica processes. In a preferred embodiment the watermark is a modification to the periodic diffraction grating effect created by the encoded data by alteration of the thickness or depth of the data feature with respect to the reference plane of the data structure in areas defining the watermark. The watermark can then be seen in the final disc as a discontinuity or difference in the rainbow-like diffraction pattern on the surface. In other embodiments, a hologram of the watermark is formed in zones on the disc, in the form of hologram interference patterns formed interspersed with the data features. These holograms can be viewed in the final disc, with white light in one embodiment, or with an illuminating laser in another embodiment, as virtual images of the watermark object.

Method of authenticating watermarked paper

Abstract: A method of authenticating watermarked paper comprises the steps of transiently heating a first surface (50) of a watermarked sheet of paper (40) using a hot air source (22); forming a thermal image of the watermark (42) using a thermal imager (30); and analysing the thermal image to determine whether or not the watermarked paper is authentic. The evolution of the thermal image with time is a characteristic of the watermark and is dependent on the local thermal mass of the paper in the region of the watermark.

Method and equipment for adding and deleting digital watermark in hierarchical picture memory and fetch system

Abstract: PURPOSE: To allow a low-resolution image to be directly fetched and, at the same time, to prevent the utilization of a high-resolution image without authentication by storing low-resolution digital images and high-resolution digital images encoded with watermarks on a recording medium. CONSTITUTION: On a digital recording medium 10, 1/16-base images, 1/4-base images, and base images with watermarks are recorded in a non-encrypting form. The base images with watermarks are formed by assembling watermarks to the base images by means of a watermark inserter 22 of watermark inserting section 34. Base images from which watermarks are to be removed are encrypted by means of a data encrypting device 26 through an encoder 20 and recorded on the medium 10. At the time of preparing a list or performing trial printing, therefore, the images with watermarks can be accessed without limitation and, at the same time, the high-resolution images from which watermarks are removed can be obtained by inputting a decoding key.

Techniques for digital image capture of watermarks

Abstract: Techniques of image analysis have been examined for their utility in documenting watermarks in historic documents and works of art on paper. The objective in documenting watermarks is to suppress the ink information on the paper and to highlight only the watermark characteristic of the sheet itself. Analysis was based on images captured in transmitted light and in reflected light. The reflected image carries information only about the behavior of the ink, whereas the transmitted image contains both ink and watermark information. Strategies for separating the ink and watermark information were explored. One technique involved a two-dimensional histogram segmentation that succeeded very well in classifying pixels as belonging either to watermark or to ink. Pixels classified as ink were assigned pixel values equal to the mean surround of the paper, thus suppressing the ink image. The second technique involved modeling the optical relationship between ink absorbance and paper transmittance. From the models, it was possible to obtain from each pixel information about the watermark.

Validating encrypted security pixel array.

Abstract: A method for protecting visual information against unauthorized access and modification using a printed cryptographic watermark includes printing a first array of shapes on a first sheet of material to be watermarked and printing a second array of shapes on a second sheet of material which is transparent and which forms a validating mask for completing a watermark encoded in a combination of the first and second arrays of shapes. The watermark is encoded by preparing an array of black and white pixels. Each pixel, which may be a square, rectangle, circle, hexagon or other shape, is split into first and second collections of subpixels, the first collection of subpixels appearing in the printed watermark and the second collection of subpixels appearing in the transparent mask. When the transparent second sheet of material is positioned directly on top of the first sheet of material with the second array of shapes aligned with the first array of shapes and the first sheet of material is viewed through the transparent second sheet of material, the encoded watermark (which was not visible in either one of the two sheets) becomes visible. A first readily perceivable image may be encoded in the first sheet, a second readily perceivable image may be encoded in the second sheet and a third image (not intimated by either of the 1st or 2nd images) may be visible in the combination of the first and second sheets. First and second sheets of material printed by this method are described.

Image Analysis for Dating of Old Manuscripts

Abstract: This paper presents an application of digital image processing to historical sciences. A major tool for dating old undated documents are watermarks found in the paper. Hardcopies of the watermarks are scanned, preprocessed, improved and contrast enhanced by adaptive digital filtering methods for printing, storing in an image database, and extracting the watermark as a set of strokes from the image. For extraction, a semiautomatical procedure is suggested. The extraction result is a short sequence of cubic spline curves representing the watermark fully and allowing to select identical or similar watermarks from the existing database.

Thematic processing and retrieving of watermarks

Abstract: This paper presents an application of digital image processing in the historical sciences it deals with the processing of x-ray recordings of watermark images taken from Middle Ages codices A sequence of processing steps for image enhancement, geometrical transformations, watermark extraction,a nd binarization is suggested The watermarks are stored together with alphanumeric information in a database, allowing the historian to retrieve and compare watermarks and to measure parameters of watermarks such as height, length, distance between special points, and radii© (1995) COPYRIGHT SPIE--The International Society for Optical Engineering Downloading of the abstract is permitted for personal use only

Image data processing unit

Abstract: PURPOSE:To compress image data while degrading of image quality is comparatively suppressed, to decode the compressed data in an excellent way and to realize a high speed access to the compressed data. CONSTITUTION:The processing unit is provided with an image data compression circuit 24 compressing n-bit image data to be supplied into m(n>m) bit image data by using the dither method, an image memory 25 storing compressed image data R0, G0, B0, and an image data expansion circuit 29 expanding the compressed image data R0, G0, B0 read from the image memory 25, the image data expansion circuit 29 compares reference picture element data with peripheral picture element data among the compressed image data from the image memory 25 and provides the output of the reference picture element data or the integrated value of the peripheral picture element data selected among the reference picture element data and the peripheral picture element data depending on the result of comparison.

Image editing device, image processor and image processing method

Abstract: PURPOSE:To provide an image editing device for enabling more highly functional image editing by a processing such as 'watermark and gradation'. CONSTITUTION:Corresponding to an editing mode signal specified by a user, a decoder 309 selects signals (image signals, the signals indicating colors and a combination ratio, etc.) inputted to respective selectors 310-313. Then, based on the selected signals, a prescribed product-sum operation processing is performed by a product-sum operation circuit 314 and the result of performing the product-sum operation processing is outputted.

Method of authenticating watermarked paper and watermark authentication system

Abstract: A method of authenticating watermarked paper comprises the steps of transiently heating a first surface (50) of a watermarked sheet of paper (40) using a hot air source (22); forming a thermal image of the watermark (42) using a thermal imager (30); and analysing the thermal image to determine whether or not the watermarked paper is authentic. The evolution of the thermal image with time is a characteristic of the watermark and is dependent on the local thermal mass of the paper in the region of the watermark.

Method and device for detecting and discriminating paper sheets

Abstract: PURPOSE:To detect and discriminate paper sheets with high discrimination accuracy by collating plural detection results of the paper sheets by areas of the paper sheets and finding the correlation among the respective detection result. CONSTITUTION:Various features incorporated in the paper sheets 1 are detected by, for example, a color detection device 2, a watermark detection device 3, and a fluorescent detection device 4 respectively. The signals of the respective detection devices 2-4 are stored in an image memory 31 through an image input device 30. The inside of the image memory 31 is divided into areas by detection, and whether or not there is a feature is embedded as data by the areas. Further, a discrimination memory 32 is provided corresponding to the image memory 31 and reference information by areas of features contents of the paper sheets 1 to be discriminated is previously embedded. A decision means 33 discriminates whether or not there is correlation of features by the areas for each output to be discriminated while collating data in the image memory 3 stored with the outputs from the paper sheet detection devices 2-4 with data in the discrimination memory 32 and outputs a discriminated result.

Production of coating-mixing type watermarked paper and watermark-forming film using therefor

Abstract: PURPOSE:To enable multikind production of fine watermarked paper. CONSTITUTION:A soluble film is coated with a coating blended coating agent 2 to obtain a watermark-forming film. Besides, a paper stock is subjected to papermaking process to obtain a base layer 1, which is then laminated with the above film and a surface layer 3 is formed thereon, to obtain the aimed watermarked paper. Because a method of coating the film with the coating agent is applied, a fine watermark can be realized. When compared with the method of making watermark by devising a watermaking screen, the above- mentioned method greatly facilitates multikind production.