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US 7,031,553 B2Granted
Method and apparatus for recognizing text in an image sequence of scene imagery
AssigneeSRI International
InventorsGregory K. Myers, Robert C. Bolles, Quang-Tuan Luong, James A. Herson
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Abstract
An apparatus and a concomitant method for detecting and recognizing text information in a captured imagery. The present method transforms the image of the text to a normalized coordinate system before performing OCR, thereby yielding more robust recognition performance. The present invention also combines OCR results from multiple frames, in a manner that takes the best recognition results from each frame and forms a single result that can be more accurate than the results from any of the individual frames.
Claims8
Method for recognizing text in a captured imagery, said method comprising the steps of:
- (a) detecting a text region in the captured imagery;
- (b) adjusting said detected text region to produce a rectified image;
- (c) applying optical character recognition (OCR) processing to said rectified image to recognize the text in the captured imagery;
- wherein said adjusting step (b) comprises the step of (b1) computing a base line and a top line for a line of detected text within said detected text region;
- wherein said base line and said top line are estimated by rotating said line of detected text at various angles and then computing a plurality of horizontal projections over a plurality of vertical edge projections;
- and
- wherein said base line is selected that corresponds to a rotation angle that yields a steepest slope on a bottom side of one of said plurality of horizontal projections.
4 more elements
Method for recognizing text in a captured imagery, said method comprising the steps of:
- (a) detecting a text region in the captured imagery;
- (b) adjusting said detected text region to produce a rectified image;
- (c) applying optical character recognition (OCR) processing to said rectified image to recognize the text in the captured imagery;
- wherein said adjusting step (b) comprises the step of (b1) computing a base line and a top line for a line of detected text within said detected text region;
- wherein said base line and said top line are estimated by rotating said line of detected text at various angles and then computing a plurality of horizontal projections over a plurality of vertical edge projections;
- and
- wherein said top line is selected that corresponds to a rotation angle that yields a steepest slope on a top side of one of said plurality of horizontal projections.
4 more elements
Method for recognizing text in a captured imagery, said method comprising the steps of:
- (a) detecting a text region in the captured imagery;
- (b) adjusting said detected text region to produce a rectified image;
- (c) applying optical character recognition (OCR) processing to said rectified image to recognize the text in the captured imagery;
- wherein said adjusting step (b) comprises the step of (b1) computing a base line and a top line for a line of detected text within said detected text region;
- said adjusting step (b) further comprises the step of (b2) computing a dominant vertical direction of character strokes for a line of detected text within said detected text region;
- and
- wherein said dominant vertical direction computing step (b2) comprises the step of computing a plurality of vertical projections over a plurality of vertical edge transitions after rotating said line of detected text in a plurality of degree increments.
4 more elements
Apparatus for recognizing text in a captured imagery, said apparatus comprising:
- means for detecting a text region in the captured imagery;
- means for adjusting said detected text region to produce a rectified image;
- and
- means for applying optical character recognition (OCR) processing to said rectified image to recognize the text in the captured imagery;
- wherein said adjusting means computes a base line and a top line for a line of detected text within said detected text region;
- wherein said base line and said top line are estimated by rotating said line of detected text at various angles and then computing a plurality of horizontal projections over a plurality of vertical edge projections;
- and
- wherein said base line is selected that corresponds to a rotation angle that yields a steepest slope on a bottom side of one of said plurality of horizontal projections.
5 more elements
Apparatus for recognizing text in a captured imagery, said apparatus comprising:
- means for detecting a text region in the captured imagery;
- means for adjusting said detected text region to produce a rectified image;
- and
- means for applying optical character recognition (OCR) processing to said rectified image to recognize the text in the captured imagery;
- wherein said adjusting means computes a base line and a top line for a line of detected text within said detected text region;
- wherein said base line and said top line are estimated by rotating said line of detected text at various angles and then computing a plurality of horizontal projections over a plurality of vertical edge projections;
- and
- wherein said top line is selected that corresponds to a rotation angle that yields a steepest slope on a top side of one of said plurality of horizontal projections.
5 more elements
Apparatus for recognizing text in a captured imagery, said apparatus comprising:
- means for detecting a text region in the captured imagery;
- means for adjusting said detected text region to produce a rectified image;
- and
- means for applying optical character recognition (OCR) processing to said rectified image to recognize the text in the captured imagery;
- wherein said adjusting means computes a base line and a top line for a line of detected text within said detected text region;
- wherein said adjusting means further computes a dominant vertical direction of character strokes for a line of detected text within said detected text region;
- and
- wherein said adjusting means computes said dominant vertical direction by computing a plurality of vertical projections over a plurality of vertical edge transitions after rotating said line of detected text in a plurality of degree increments.
5 more elements
Method for recognizing text in a captured imagery, where said captured imagery is of a three-dimensional scene, said method comprising the steps of:
- (a) detecting a text region in the captured imagery;
- (b) adjusting along three axes said detected text region to produce a rectified image, wherein said adjusting comprises the steps of:
- (b1) computing a base line and a top line for a line of detected text within said detected text region;
- and
- (b2) computing a dominant vertical direction of character strokes for a line of detected text within said detected text region, wherein said dominant vertical direction computing further comprises the step of computing a plurality of vertical projections over a plurality of vertical edge transitions after rotating said line of detected text in a plurality of degree increments;
- and
- (c) applying optical character recognition (OCR) processing to said rectified image to recognize the text in the captured imagery.
4 more elements
Dependencies are inferred from the claim text.