Sequenced illumination
First Claim
1. A system for imaging documents, comprising:
- an image sensor comprising a line scan camera, the line scan camera adapted to capture a plurality of line images of a document, at least two of the plurality of line images captured under differing modes of illumination, wherein the line scan camera comprises a plurality of light sensors forming a column, the column perpendicular to a direction of travel of the document;
at least two different light sources, wherein each light source produces a different mode of illumination;
a memory storing a lookup table that divides documents into discrete successive sections and specifies a mode of illumination for each section of said document during imaging; and
means for synchronizing said light sources with said image sensor to sequentially illuminate the document passing in front of the image sensor in accordance with said lookup table, producing an interleaved, multi-mode image of said document, the interleaved, multi-mode image comprising at least a first portion and a second portion, the first portion of the interleaved, multi-mode image produced while a first light source in the at least two different light sources illuminates said document, the second portion of the interleaved, multi-mode image produced while a second light source is the at least two different light sources illuminates said document.
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Accused Products
Abstract
The present invention provides a method and system for imaging documents such as bank notes. The method comprises passing a document past an image sensor such as a line scan camera while sequentially illuminating the document using multi-mode illumination. Two or more light sources are used, each one producing a different mode of illumination. A lookup table divides documents into discrete successive sections (i.e. scan lines) and specifies a mode of illumination (e.g., color, azimuth, reflective, transmissive) for each section of a document during imaging. As the document passes the image sensor, the light sources are activated according to the sequence specified in the lookup table, producing an interleaved, multi-mode image of the document.
108 Citations
20 Claims
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1. A system for imaging documents, comprising:
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an image sensor comprising a line scan camera, the line scan camera adapted to capture a plurality of line images of a document, at least two of the plurality of line images captured under differing modes of illumination, wherein the line scan camera comprises a plurality of light sensors forming a column, the column perpendicular to a direction of travel of the document; at least two different light sources, wherein each light source produces a different mode of illumination; a memory storing a lookup table that divides documents into discrete successive sections and specifies a mode of illumination for each section of said document during imaging; and means for synchronizing said light sources with said image sensor to sequentially illuminate the document passing in front of the image sensor in accordance with said lookup table, producing an interleaved, multi-mode image of said document, the interleaved, multi-mode image comprising at least a first portion and a second portion, the first portion of the interleaved, multi-mode image produced while a first light source in the at least two different light sources illuminates said document, the second portion of the interleaved, multi-mode image produced while a second light source is the at least two different light sources illuminates said document. - View Dependent Claims (2, 3, 4, 5, 6, 13, 14, 19)
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7. A method for imaging documents, comprising:
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passing a document past an image sensor, the image sensor comprising a line scan camera, the line scan camera adapted to capture a plurality of line images of the document, at least two of the plurality of line images captured under differing modes of illumination, wherein the line scan camera comprises a plurality of light sensors forming a column, the column perpendicular to a direction of travel of the document; accessing a lookup table that divides documents into discrete successive sections and specifies a mode of illumination for each section of said document during imaging; and sequentially illuminating said document as it passes said image sensor using multi-mode illumination to produce an interleaved, multi-mode image of said document, the interleaved, multi-mode image comprising at- least a first portion and a second portion, the first portion of the interleaved, multi-mode image produced while a first mode of illumination illuminates said document, the second portion of the interleaved, multi-mode image produced while a second mode of illumination illuminates said document. - View Dependent Claims (8, 9, 10, 11, 12, 18, 20)
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15. A system for imaging documents, comprising:
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an image sensor comprising a line scan camera, the line scan camera adapted to capture a plurality of line images of a document, at least two of the plurality of line images captured under differing modes of illumination, wherein the line scan camera comprises a plurality of light sensors forming a column, the column perpendicular to a direction of travel of the document; at least two different light sources, wherein each light source produces a different mode of illumination; and means for synchronizing said light sources with said image sensor to sequentially illuminate the document passing in front of the image sensor, producing an interleaved, multi-mode image of said document, the interleaved, multi-mode image comprising at least a first portion and a second portion, the first portion of the interleaved, multi-mode image produced while a first light source in the at least two different light sources illuminates said document, the second portion of the interleaved, multi-mode image produced while a second light source is the at least two different light sources illuminates said document, the system further comprising a processor to process the interleaved, multi-mode image to determine a feature of said document, wherein the processor applies a transformation function to data extracted from the interleaved, multi-mode image of said document to determine a three-dimensional measurement; and wherein the processor further computes a projection of the three-dimensional measurement to a reference vector to determine a fitness value, the fitness value used to determine the feature of said document. - View Dependent Claims (16, 17)
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Specification