Xerox Corporation

Mauritius Seeger

Christopher R Dance

Stuart Taylor

William M Newman

Michael J Flynn

Ercan E Kuruoglu

Alex S Taylor

A system enables users at different locations (e.g. different geographic locations) to work collaboratively on a document, and to view each other's annotations to the document. Each user can work with a paper document, and make handwritten annotations to the paper document. The system includes a plurality of workstations communicating with a server. Each workstation comprises a document-imaging device, such as a camera, for generating a digital image of the document. Handwritten annotations are identified by image processing, and new annotations made by each user can be tracked in real time. Image bitmaps of the annotations are distributed by the server to each workstation so that each user can view other user's annotations. In one view, the annotations from different users are superimposed in a combined image.

Method and apparatus for collaborative annotation of a document

A camera can be used to record multiple low resolution images of an object by shifting a camera lens relative to an image sensor of the camera. Each camera image recorded represents a portion of the object. A composite high resolution image of the object can be obtained by patching together the camera images by using various well known mosaicing, tiling, and/or stitching algorithms.

Mosaicing images with an offset lens

A camera apparatus obtains a sharp, high-resolution image of an object which is difficult to focus in a single image at a fixed focus, such as the imaging of a document using a document camera held at an oblique angle to the document. The apparatus composites an image of an object from plural image segments of the object acquired at different focusing distances. High quality regions (i.e. sharply focused and/or high resolution) are extracted from each image to form the segments for compositing.

Apparatus and method for capturing a composite digital image with regions of varied focus and magnification

A document image capture (scanning) system and control method are described for scanning and processing document images received live from a camera. A motion detector detects image motion between two image frames. When the image is stationary, image processing (such as OCR) is carried out automatically and made available to the operator. In one form, when movement is detected, the image processing results are discarded until the image is newly stationary, whereupon new image processing is carried out on the new image. In another form, the degree of movement is evaluated; if the movement is small, then at least some of the previous image processing results are re-used by re-mapping on to the new image.

System with motion triggered processing

An apparatus and method are described for processing a captured (e.g. scanned) image. The apparatus includes a plurality of selection tools for selecting a region of the image to be processed. The selection tools include a word-by-word selection tool for text and a rectangular box selection tool for a picture. The apparatus also includes a plurality of copy tools for copying the selected region. The appropriate selection tool and copy tool are controlled automatically by a global mode control, being one of a text mode, a color picture mode and a black-and-white picture mode. Optionally, the apparatus displays the image in one of a plurality of different display modes, the display mode also being controlled by the global mode control.

Method and apparatus for image capture, selection and copying

Following scanning of a document image, and optical character recognition (OCR) processing, the outputted OCR text is processed to determine a text format (typeface and font size) to match the OCR text to the originally scanned image. The text format is identified by matching word sizes rather than individual character sizes. In particular, for each word and for each of a plurality of candidate typefaces, a scaling factor is calculated to match a typeface rendering of the word to the width of the word in the originally scanned image. After all of the scaling factors have been calculated, a cluster analysis is performed to identify close clusters of scaling factors for a typeface, indicative of a good typeface fit at a constant scaling factor (font size).

Method and apparatus for formatting OCR text

An image processing technique for selecting a text region from an image is described. Character and formatting information for each word in the image is used to determine an active region for each word in the image. For a preferred embodiment of the present invention, the character and formatting information is derived during optical character recognition (OCR). A first and last word within a selected text region is identified based on at least one active region associated with at least one word within the selected text region. Using the first and last words within the selected text region, all words within the selected text region are identified. An image of the selected text region may be displayed. Text contained within the selected text region may be copied to an application program.

Word-to-word selection on images

A thresholding technique for generating a background image of a pixmap image is described. For one embodiment of the present invention, background image is used to generate a background threshold surface for thresholding a pixmap image. For another embodiment of the present invention, the background image is used to normalize the background of the pixmap image. In yet another embodiment of the present invention, the background image is used as input for other image processing algorithms such as extracting features from a grey-scale image for character recognition.

Background surface thresholding

A composite higher resolution image of an object can be obtained by combining or patching together multiple low-resolution camera images to form a composite image having a higher resolution. Each low-resolution camera image represents a subsection of an object (also referred to as &ldquo;object subsection&rdquo;) to be scanned. For example, each subsection may represent a quadrant of a document page. With the use of a periscope, the image visible to the camera can be shifted to capture images of the various object subsections. Mosaicing techniques are used to combine these camera images into a composite image of the object. This approach to scanning improves the resolution of documents scanned while using existing low cost video cameras.

Document periscope

A document camera is described for capturing an electronic image of a document, for subsequent optical character recognition. In order to avoid the need for a user to look through a viewfinder of the camera, the camera comprises a projector for projecting an optical field of view indicator on to the document. The user can see the projected indicator on the document page, indicating the effective field of view of the camera. The camera may include auto-focus and zooming mechanisms. In one form, the camera processes a detected image to determine a capture zone corresponding to whole regions of the document falling entirely within the field of view. The projected indicator is controlled to indicate only the capture zone. When the image is to be captured, the camera zooms in to the capture zone to capture the image at maximum resolution.

Method and apparatus for indicating a field of view for a document camera

A point spread function (PSF) of a digital camera is measured in two-dimensions. To measure the PSF in two dimensions a grid of dots is defined on a calibration chart. The calibration chart is recorded with the digital camera to define a calibration image. The grid of dots recorded in the calibration image has dots with three different sizes. The two of the largest sizes of dots are used to provide a coarse-to-fine registration of the calibration image with the calibration chart. Once aligned, the locations of the smallest of the dots in the calibration image are used to define a composite dot image. The level of noise in the composite dot image is minimized by averaging over many small dots in the grid of dots. In addition, the composite dot image is super-resolved in order to minimize the effects of aliasing. Once the PSF is measured for the digital camera, the PSF can be used in a restoration filter to remove blur in images recorded with the digital camera.

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Royston, United Kingdom

Mauritius Seeger