Method and apparatus for extracting information from a target area within a two-dimensional graphical object in an image
First Claim
1. A method of extracting information from a target area within a two-dimensional graphical object having a plurality of predetermined features with known characteristics in a first plane, comprising the steps of:
- reading an image in which said object is located in a second plane, said second plane being a priori unknown;
in said image, identifying a plurality of candidates to said predetermined features in said second plane;
from said identified plurality of feature candidates, calculating a transformation matrix for projective mapping between said second and first planes;
transforming said target area of said object from said second plane into said first plane, and processing said target area so as to extract said information.
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Abstract
A method is presented for extracting information from a target area within a two-dimensional graphical object having a plurality of predetermined features with known characteristics in a first plane. An image is read where the object is located in a second plane, which is a priori unknown. A plurality of candidates to the features in the second plane are identified in the image. A transformation matrix for projective mapping between the second and first planes is calculated from the identified feature candidates. The target area of the object is transformed from the second plane into the first plane. Finally, the target area is processed so as to extract the information.
105 Citations
27 Claims
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1. A method of extracting information from a target area within a two-dimensional graphical object having a plurality of predetermined features with known characteristics in a first plane, comprising the steps of:
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reading an image in which said object is located in a second plane, said second plane being a priori unknown;
in said image, identifying a plurality of candidates to said predetermined features in said second plane;
from said identified plurality of feature candidates, calculating a transformation matrix for projective mapping between said second and first planes;
transforming said target area of said object from said second plane into said first plane, and processing said target area so as to extract said information. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21)
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22. An apparatus for extracting information from a target area within a two-dimensional graphical object having a plurality of predetermined features with known characteristics in a first plane, the apparatus comprising an image sensor, a processing device and storage means, comprising
a first area in said storage means, said first area being adapted to store an image, as recorded by said image sensor, in which said object is located in a second plane, said second plane being a priori unknown; - and
a second area in said storage means, said second area being adapted to store said plurality of predetermined features;
wherein;
said processing device being adapted to read said image from said first area;
read said plurality of predetermined features from said second area;
identify, in said image, a plurality of candidates to said features in said second plane;
calculate, from said identified feature candidates, a transformation matrix for projective mapping between said second and first planes;
transform said target area of said object from said second plane into said first plane; and
, after transformation, extract said information from said target area. - View Dependent Claims (23, 24, 25, 26, 27)
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Specification