Hewlett-packard Development Company, L.P.

Hewlett-packard Company

Cormac Herley

Poorvi L Vora

Ping Wah Wong

Xuguang Yang

Chit Wei Saw

Slawomir K Ilnicki

Joyce E Farrell

Yihong Xu

Christian J Van Den Branden Lambrecht

Joan Maria Mas Ribes

Doron Shaked

Izhak Baharav

Jonathan Yen

Terry P Mahoney

Angela Kay Hanson

Avraham Levy

Timothy Harrison

A system for distributing digital content over a computer network (e.g., the Internet) uses certificates to establish a trust relationship between a content provider and a display device. The certificates identify the display device and the content provider as well as unique characteristics of the distribution. For example, the content provider may be a book publisher and the display device may be a printer/binder.

Digital content distribution systems

Opportunistic image quality improvement in a digital camera. In a digital camera having a picture memory of fixed size for storing a predetermined number of pictures, raw image data is compressed to form primary and auxiliary data sets. The primary data set allows the image to be reconstructed at a first quality level. The primary and auxiliary data sets combined allow the reconstruction of the image at a higher quality level. As images are taken and processed, if sufficient storage space exists in the picture memory, both primary and auxiliary data sets are stored. This continues until the memory is full of primary and auxiliary data sets. Once the memory is full, as more images are taken and stored, the space used by auxiliary data sets is reclaimed for use by primary data sets, and the auxiliary data sets are not stored.

Opportunistic improvement of digital camera image quality

The present invention is directed to methods and apparatus that partially encrypt an information data file. An exemplary method includes dividing the information file into a first file and a second file, wherein the second file includes content from the information file to preclude reconstruction of the information file using only the first file, and encrypting the second file. Additionally, the method provides for transmitting the first file and the encrypted second file from a first device to a second device.

Method and apparatus for partial encryption of content

A barcode system for generating and decoding a barcode with visual significance. The barcode system of the present invention includes an encoding module for receiving a message and a logo and generating a visually significant barcode based on these inputs. A decoding module is also provided for receiving an acquired version of a visually significant barcode that may have been degraded in a typical document handling channel (e.g., through the printing, scanning, or copying process) and for recovering the message specified by the visually significant barcode.

Method and apparatus for generating and decoding a visually significant barcode

A method and apparatus is described for detection and deterrence of counterfeiting that permits one to make legitimate color copies without introducing visual artifacts or experiencing substantial processing delays. The scheme detects a characteristic color of frequently counterfeited documents and alters the characteristic color in the copies. The scheme exploits the fact that conversion between color spaces is frequently accomplished using a color Look-Up Table (LUT). Because it represents no computational burden to alter the values in the LUT, we can efficiently modulate slightly the value of the characteristic color in a way that depends on the value of the counter. For example, at first even banknote green is rendered correctly. However, as the page uses more and more of the ink, a modulation function causes conversion to a darker value than the actual green requested. After using a significant portion of the ink required to render a banknote, the modulation function can switch again, and cause a lighter than requested green to be returned. The net effect of using this modulation function is that distinct bands will appear when an image of a banknote is printed. These visible marks appear on the page independently of the orientation of the note. If we consider a general image with a lot of green, we find that there is no visible difference between versions of the image rendered with and without the modulation scheme. The reason for this is that although many pixels of the general image may meet the criterion of being classified as &ldquo;banknote green&rdquo; in the LUT, they are dispersed and a minor increase or decrease in the value is not as noticeable as when a large amount of that ink is used in close proximity, as is the case on the back of a banknote.

Detection and deterrence of counterfeiting of documents having a characteristic color

Detection and deterrence of counterfeiting permits one to make legitimate color copies without introducing visual artifacts or experiencing substantial processing delays. We enable an efficient counterfeit deterrence by the use of an hierarchic detection scheme, in which the majority of documents are classified as free of suspicion using a simple algorithm that imposes a negligible computational burden. The remainder of documents, which are labeled as suspicious, receive analysis by one or more potentially complex detection algorithms. If the suspicious document is identified as being a secure document, this will lead to printing with selectively deteriorated service or complete denial of service. For one embodiment, the scheme uses a color look-up table (LUT) to detect a characteristic color (or colors) of frequently counterfeited documents and alters the characteristic color in the copies if a more accurate second test verifies that printing of a counterfeit is being attempted. A conventional test for counterfeit documents can be used as a second (or higher) level test. A particularly effective second level detector characterizes a suspicious pattern by the size of the suspected area, and the frequency of the transition between the foreground and background colors.

Multi-level detection and deterrence of counterfeiting of documents with reduced false detection

A method and apparatus is described for detection and deterrence of counterfeiting that permits one to make legitimate copies without introducing substantial visual artifacts or experiencing substantial processing delays by imposing a small, random, offset or jitter into the position upon a page where printing of a copy of a document begins. The jitter makes it extremely unlikely that the registration icons align when the secure document is copied. The misalignment of the icons signal that the copy is a counterfeit. In one implementation, the jitter is always introduced and, in another implementation, jitter is only introduced when counterfeiting is possible, or likely.

Detection and deterrence of counterfeiting of two-sided documents

A method to reduce the distortion introduced by lossy compression of interpolated images. The interpolation represents a constraint. If the output of the compression algorithm does not satisfy the constraint then the estimate of the output can be improved by re-imposing the constraint. An alternating projection algorithm is used to impose both the interpolation constraint, and the requirement that the image compress to the observed compressed output. This involves finding the orthogonal projection alternately on the space of interpolated images, and on the set of images that quantize to the appropriate image produced by the compression algorithm. Although this algorithm is not restricted to the correction of errors in block coding schemes, the explicit introduction of the interpolation constraint allows this algorithm to outperform all other iterative algorithms that attempt only to remove blocking artifacts introduced by transform coders. An important special case is the case of color interpolated images, and JPEG compression. This method is able to improve the output image both in terms of mean squared error and visual appearance.

Artifact reduction decompression method and apparatus for interpolated

A technique, referred to as area-based interpolation, performs image interpolation. The system determines a curve by the pixel value at a location by taking the integral of a curve over a small area, where the size of the area is determined by the sampling size of a sampling cell. When the image is resampled with respect to a sampling cell that has a finer spacing, the system integrates the polynomial using a finer integration area. In accordance with the invention, the relation between the reintegrated, resampled high resolution image and the low resolution image is a function of an up-sampler, followed by a linear filter. The coefficients of the filter are independent of the data, but are dependent on the family of curves used. If the system models by, for example, a third degree or fourth degree polynomial everywhere in the image, then that model determines the number of coefficients that are in the filter. Once the up-sampling factor and degree of the polynomial are determined, the filter coefficients are fixed, and can be calculated by solving a set of linear equations. It is not necessary to determine these values on an image-by-image basis. The system calculates the filter once and the consistency constraint is then satisfied for all image scaling.

Area based interpolation for image scaling

A process and apparatus is described to improve the fidelity of compressed demosaiced images by decreasing the error introduced for a given compression ratio. Because (typically) two out of three of the color values at any location of the demosaiced image are interpolated, most of the loss can be concentrated into these values, so that the actual or measured data values have little loss. This is achieved by finding an interpolation of the data such that the original measured values suffer minimal loss in the lossy compression, while the loss for the other interpolated values may be arbitrarily large. Thus, rather than performing an interpolation first and accepting whatever loss the compression scheme (e.g., JPEG) gives, the values to be interpolated are treated as 'Don't cares' and then provided so as to minimize the loss for the measured values. The algorithms presented require no additional memory and entail a reasonable increase in run-time.

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Los Gatos, CA, United States of America

Cormac Herley