Method and system for recognizing a candidate character in a captured image
AssigneeSeiko Epson Corporation
InventorsIan Clarke, Hui Zhou, Jeffrey Matthew Achong
Life of this patent
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Abstract
A system and method of recognizing characters in a captured image, includes selecting a portion of the image encompassing a string of characters in the captured image to be recognized. The selected portion is examined to identify segments that potentially include the characters of the string. During the examining multiple tests on pixels in the selected portion are performed. The identified segments are then examined to recognize the string of characters.
Claims29
A method of identifying candidate characters of a character string in a captured image, the method comprising using a processor to perform the steps of:
- identifying special characters within the captured image of said character string, including:
- performing a Fast Fourier Transform (FFT) on a portion of the captured image;
- performing an inverse FFT yielding a cross-correlation image representing a cross-correlation between the captured image and a character template image corresponding to the special characters;
- box-filtering the cross-correlation image to smooth the cross-correlation image;
- subtracting the box-filtered image from the cross-correlation image yielding a modified cross-correlation image;
- and
- based at least in part on the modified cross-correlation image, identifying the special characters;
- determining a bounding box generally encompassing said character string based on the identified special characters;
- determining segments of said bounding box containing candidate characters;
- comparing each determined segment of said bounding box with at least one character template image, each character template image including features associated with a respective character to be recognized;
- and
- identifying a candidate character when said segment includes image information corresponding to one of a set of character template images.
A method of recognizing characters of a character string in an image, comprising using a processor to perform the steps of:
- identifying designated characters of said character string comprising:
- performing a Fast Fourier Transform (FFT) on a portion of the captured image;
- performing an inverse FFT yielding a cross-correlation image representing a cross-correlation between the captured image and a character template image corresponding to the designated characters;
- box-filtering the cross-correlation image to smooth the cross-correlation image;
- subtracting the box-filtered image from the cross-correlation image yielding a modified cross-correlation image;
- and
- based at least in part on the modified cross-correlation image, identifying the designated characters;
- using the location of the designated characters to determine a bounding box generally encompassing said character string;
- determining segments of said bounding box containing candidate characters;
- performing character recognition using a neural network by comparing each determined segment of said image containing a candidate character to be recognized with a plurality of character template images representing recognizable characters;
- when the candidate character of a determined segment corresponds to one of said character template images, recognizing the candidate character as that represented by said one character template image;
- and
- when the candidate character of a determined segment corresponds to a plurality of said character template images, using a correlation between the determined segment and each character template image of the plurality to recognize the candidate character as that represented by one character template image of said plurality.
Dependencies are inferred from the claim text.