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US 7,463,772 B1Granted
De-warping of scanned images
AssigneeGoogle Inc.
InventorsFrancois-Marie Lefevere, Marin Saric
Life of this patent
Estimating the term…
Abstract
A system includes a stereoscopic camera to generate images of a document, such as a book, that can be converted to a three-dimensional contour of the document. A second camera take a two-dimensional image of the document. A model is generated that defines a mapping between the three-dimensional contour of the document and a two-dimensional flattened (de-warped) version of the document. The model may be applied to the two-dimensional image taken by the second camera to compensate for warping in the image.
Claims27
A system comprising:
- an infrared projector to project infrared radiation in an output path toward a page of a document;
- a pattern mask located in the output path of the infrared projector;
- an infrared stereoscopic camera to generate images of the page of the document from which a three-dimensional image of a surface of the page of the document is generated a second camera to generate a two-dimensional image of the page of the document;
- and
- control logic to process the three-dimensional image and the two-dimensional image and to generate a model that relates the three-dimensional image of the surface of the page of the document to a flat, un-warped two-dimensional image of the page.
2 more elements
A method comprising:
- generating a model, that describes a three-dimensional profile of a surface of a document relative to a two-dimensional un-warped profile of the surface by:
- locating with an infrared stereoscopic camera a first set of lines in a three-dimensional image of the surface of the document;
- and
- determining two-dimensional lines corresponding to the first set of lines in the two-dimensional un-warped profile of the surface;
- and
- storing the model, in a computer-readable medium, as the first set of three-dimensional lines in the three-dimensional image of the surface and the corresponding determined two-dimensional lines.
3 more elements
A device comprising:
- means for sensing infrared radiation to locate a first line in a three-dimensional image of a surface of a document;
- means for fitting a next line in the three-dimensional image of the surface at a predetermined distance from the first line;
- means for determining a two-dimensional line equation corresponding to the next line in a two-dimensional profile of the surface;
- and
- means for storing a model that includes a plurality of fitted next lines and the corresponding two-dimensional line equations, the model describing a three-dimensional profile of a surface of the document relative to a two-dimensional un-warped surface of the document.
2 more elements
A method comprising:
- generating a model, that describes a three-dimensional profile of a surface of a document relative to a two-dimensional un-warped profile of the surface by:
- generating a first series of equations for a first set of points in a three-dimensional image of the surface of the document and the two-dimensional un-warped profile of the surface of the document that define stretching of the document between the first set of points;
- generating a second series of equations for a second set of points in the three-dimensional image of the surface of the document and the two-dimensional un-warped profile of the surface of the document that define a shearing of the document between the second set of points;
- and minimizing the stretching and shearing of the document defined by the first and second series of equations;
- and storing the model, in a computer-readable medium, based on the second set of points minimized for stretching and shearing.
2 more elements
A method of compensating for distortion in a two-dimensional image of a document, the method comprising:
- gathering a three-dimensional image of a contour of a surface of the document by detecting non-visible infrared radiation;
- processing the three-dimensional image of the contour of the surface of the document to obtain a model relating the three-dimensional contour of the surface to a flat two-dimensional contour of the surface of the document;
- projecting the two-dimensional image to a three-dimensional image based on the three-dimensional contour of the surface;
- and
- re-projecting the projected three-dimensional image to a second two-dimensional image based on the model, where the second two-dimensional image is compensated for distortion.
2 more elements
A method of compensating for distortion in a two-dimensional image of a document, the method comprising:
- gathering three-dimensional image data of a contour of a surface of the document from an infrared stereoscopic camera;
- processing the three-dimensional image data to obtain a model relating the three-dimensional contour of the surface to a flat two-dimensional contour of the surface of the document, the model being generated by sequentially fitting a series of three-dimensional lines along a surface of the document and mapping the series of three-dimensional lines to a corresponding series of two-dimensional lines;
- projecting the two-dimensional image to a three-dimensional image based on the three-dimensional contour of the surface;
- and
- re-projecting the projected three-dimensional image to a second two-dimensional image based on the model, whereby the second two-dimensional image is compensated for distortion.
2 more elements
Dependencies are inferred from the claim text.