Abstract: A method for encoding and decoding color barcodes to increase their data capacity. The encoding steps include determining a shape, a foreground color and a background color for each data cell, wherein a combination of the shape, foreground and background colors for the data cell is chosen from a plurality of such combinations in accordance with a value of the digital data to be encoded; and coloring some pixels in the data cell with a foreground color and other pixels with a background color, in accordance with the shape, foreground and background colors for the data cell determined above. The decoding steps include segmenting the data cells, recognizing a shape, a foreground color of the shape and a background color of the data cell, and obtaining digital data from a combination of the shape and foreground and background colors in each data cell.

Abstract: A method and program for encoding and decoding color barcodes to increase their data capacity. The encoding steps include determining a shape and a color for each data cell to encode digital data, wherein a combination of the shape and the color for the data cell is chosen from a plurality of combinations of shapes and colors in accordance with a value of the digital data to be encoded, and coloring a subset of the plurality of pixels in each data cell in accordance with the shape and the color for the data cell determined above. The decoding steps include segmenting the data cells in a color barcode, recognizing a shape formed by a subset of pixels in each data cell and the color of the shape, and obtaining digital data from a combination of the recognized shape and color in each data cell.

Abstract: A method of generating a self-authenticating printed document and authenticating the printed document. The back side of the printed document contains 2d barcode which encode extracted features of the document content. The features are hashed into a hash code, converted to a barcode stamp element, and transformed into a hierarchical barcode stamp by repeating the stamp element. The hierarchical barcode stamp is printed as a gray background pattern on the front side of the same sheet of printed document. To authenticate the printed document, the barcodes on the back side are read to extract the document features. The features are hashed into a hash code and compared to the hash code extracted from the hierarchical barcode stamp on the front side of the document to detect any alterations of the back side barcodes. Further, the document features extracted from the front and back sides of the document are compared.

Abstract: A pair of spectacles that can automatically change its power so that a fixation region of interest (ROI) of the user is always in focus. The automatic accommodative spectacle device includes focusing elements, scene sensors, scene analyzer, focus engine, focusing element controller, and power supply. The scene analyzer determines the fixation ROI in the scene by analyzing the scene images. The fixation ROI is used to determine powers for the focusing elements in order to bring the fixation ROI into focus. The focusing element controller carries out the needed optical power adjustment to apply to the focusing elements. Optional light sources may be provided to the scene sensors. Additional optional eye sensor(s), eye light source and line of sight detector can be used to help the scene analyzer extract the fixation ROI.

Abstract: A pair of spectacles that can automatically change its power so that a fixation region of interest (ROI) of the user is always in focus. The automatic accommodative spectacle device includes focusing elements, sensors, line of sight detector, focus engine, focusing element controller, and power supply. The line of sight detector determines the line of sight for the left and right eyes of the user using data from the sensors. The focus engine uses the lines of sight for left and right eyes to determine the user's fixation ROI. The fixation ROI is used to determine powers for the focusing elements in order to bring the fixation ROI into focus. The focusing element controller carries out the needed optical power adjustment to apply to the focusing elements. Optional light sources may be provided.

Abstract: A document authentication method compares a target document image (scanned image) with an original document image at multiple levels, such as block (e.g. paragraph, graphics, image), line, word and character levels. The paragraph level comparison determines whether the target and original images have the same number of paragraphs and whether the paragraphs have the same sizes and locations; the line level comparison determines if the target and original images have the same number of lines and whether the lines have the same sizes and locations; etc. Document segmentation is performed on the target and original images to segment them into paragraph units, line units, etc. for purposes of the comparisons. The original document may be segmented beforehand and the segmentation information stored for later use. The authentication process may be designed to stop when alterations are detected at a higher level, so lower level comparisons are not carried out.

Abstract: A method for authenticating a printed document is disclosed. Barcode stamps are added to an original document image near the corners of the page to act as registration markers. The original document image bearing the barcode stamps is printed and circulated, while the original document image is stored in a database. To authenticate a printed document, the printed document is scanned into a target document image, which is compared to the stored original document image. The barcode stamps are used as registration markers to perform a global image registration. Then, the target image and the original image are divided into multiple sub-images, and local image registration is performed on the sub-images before performing an image comparison. Difference sub-images are generated from the pairs of sub-images, and merged into a global difference image for the purpose of detecting any alterations in the printed document.

Abstract: A document authentication method compares a target document image (scanned image) with an original document image at multiple levels, such as block (e.g. paragraph, graphics, image), line, word and character levels. The paragraph level comparison determines whether the target and original images have the same number of paragraphs and whether the paragraphs have the same sizes and locations; the line level comparison determines if the target and original images have the same number of lines and whether the lines have the same sizes and locations; etc. Document segmentation is performed on the target and original images to segment them into paragraph units, line units, etc. for purposes of the comparisons. The original document may be segmented beforehand and the segmentation information stored for later use. The authentication process may be designed to stop when alterations are detected at a higher level, so lower level comparisons are not carried out.

Abstract: A document alteration detection method compares a target image with an original image using a two-step process. In the first step, the original and target images are divided into connected image components and their centroids are obtained, and the centroids of the image components in the original and target images are compared. Each centroid in the target image that is not in the original image is deemed to represent an addition, and each centroid in the original image that is not in the target image is deemed to represent a deletion. In the second step, sub-images containing the image components corresponding to each pair of matching centroids in the original and target images are compared to detect any alterations.

Abstract: A method for authenticating a printed document is disclosed. Barcode stamps are added to an original document image near the corners of the page to act as registration markers. The original document image bearing the barcode stamps is printed and circulated, while the original document image is stored in a database. To authenticate a printed document, the printed document is scanned into a target document image, which is compared to the stored original document image. The barcode stamps are used as registration markers to perform a global image registration. Then, the target image and the original image are divided into multiple sub-images, and local image registration is performed on the sub-images before performing an image comparison. Difference sub-images are generated from the pairs of sub-images, and merged into a global difference image for the purpose of detecting any alterations in the printed document.

Abstract: A method of generating a self-authenticating printed document and authenticating the printed document. The back side of the printed document contains 2d barcode which encode extracted features of the document content. The features are hashed into a hash code, converted to a barcode stamp element, and transformed into a hierarchical barcode stamp by repeating the stamp element. The hierarchical barcode stamp is printed as a gray background pattern on the front side of the same sheet of printed document. To authenticate the printed document, the barcodes on the back side are read to extract the document features. The features are hashed into a hash code and compared to the hash code extracted from the hierarchical barcode stamp on the front side of the document to detect any alterations of the back side barcodes. Further, the document features extracted from the front and back sides of the document are compared.

Abstract: A method is described to obtain a binary image from the print-and-scan process to best match the known original. A point-spread function (PSF) of the PAS process is first obtained from its knife-edge responses, and deblurring is carried out on the scanned images using deconvolution. After image deskewing and preliminary registration, a supervised adaptive thresholding procedure is utilized to binarize the scanned image such that a measure of difference (e.g. the Euclidean distance) between the original and binarized images is minimized. The supervised adaptive thresholding procedure divides the scanned images into many rectangular sub-images. Otsu's method is used to find a starting threshold for each scanned sub-image. An optimal threshold is found around the Otsu's threshold via iterative search to minimize the measure of difference between the original sub-image and scanned sub-image. The sub-images are binarized using the optimal threshold. This method may be used in document authentication.

Abstract: An image deblurring method for camera-based document image processing is described. A document image captured by a digital camera is divided into multiple overlapping or non-overlapping sub-images. A point spread function is derived for each sub-image by analyzing the gradient information along edges contained in the sub-image. Each sub-image is deblurred by using its local point-spread function. The whole deblurred image is constructed from deblurred sub-images. In cases where information of interest is located in localized parts of the document image, dividing the image into sub-images may be done by extracting the area of interest from the captured image. This deblurring method improves the quality of the deblurred image when the camera-captured image is blurred by variable amount of location-dependent defocus.

Abstract: A document alteration detection method compares a target image with an original image using a two-step process. In the first step, the original and target images are divided into connected image components and their centroids are obtained, and the centroids of the image components in the original and target images are compared. Each centroid in the target image that is not in the original image is deemed to represent an addition, and each centroid in the original image that is not in the target image is deemed to represent a deletion. In the second step, sub-images containing the image components corresponding to each pair of matching centroids in the original and target images are compared to detect any alterations.