Segmentation process for machine reading of handwritten information
First Claim
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1. In the machine-reading of original handwritten word or number script, a method for normalizing the characteristic slant angle in the script, comprising the steps of:
- generating a pixel map of said original script, with said script image aligned on said map in a direction substantially parallel to the horizontal axis of said pixel map;
said map comprising vertical columns and horizontal rows of dark and white pixels, said dark pixels displaying the script of said word or number, and said display exhibiting said characteristic script slant angle relative to said vertical columns;
moving said rows of pixels thereby to generate a first altered script image having a first slant angle;
calculating the total number of dark pixels in said first altered image;
calculating the number of dark pixels in each said vertical column of said first altered image;
calculating the proportion of dark pixels in each column relative to said total dark pixels in said first altered image;
using said proportionality value, computing the entropy value of said first altered image for said first slant angle;
storing said computed entropy value and its associated first slant angle;
successively repositioning said rows of pixels thereby to generate a succession of further altered script images, each of said last-named images having a different slant angle;
computing and storing the entropy values and the respective associated slant angle values for each said further altered image;
determining the angular difference between that slant angle associated with the minimum entropy value and the characteristic slant angle; and
with the pixel rows in their original image position, shifting said pixel rows by the amount of said angular difference, thereby to create an image of said handwritten script that has its characteristic slant angle removed.
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Abstract
An improved machine process for recognizing the transition point between letters and digits in handwritten text is disclosed. The script, digits and/or letters, is mapped onto a pixel matrix. The entropy for each column for a range of assumed slant angles is analyzed to determine the angle at which image entropy is a minimum. By reverse-shifting the pixel array an amount equal to this angle, the slant component of the script is verticalized and the segmentation step which follows is more accurately accomplished.
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Citations
7 Claims
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1. In the machine-reading of original handwritten word or number script, a method for normalizing the characteristic slant angle in the script, comprising the steps of:
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generating a pixel map of said original script, with said script image aligned on said map in a direction substantially parallel to the horizontal axis of said pixel map; said map comprising vertical columns and horizontal rows of dark and white pixels, said dark pixels displaying the script of said word or number, and said display exhibiting said characteristic script slant angle relative to said vertical columns; moving said rows of pixels thereby to generate a first altered script image having a first slant angle; calculating the total number of dark pixels in said first altered image; calculating the number of dark pixels in each said vertical column of said first altered image; calculating the proportion of dark pixels in each column relative to said total dark pixels in said first altered image; using said proportionality value, computing the entropy value of said first altered image for said first slant angle; storing said computed entropy value and its associated first slant angle; successively repositioning said rows of pixels thereby to generate a succession of further altered script images, each of said last-named images having a different slant angle; computing and storing the entropy values and the respective associated slant angle values for each said further altered image; determining the angular difference between that slant angle associated with the minimum entropy value and the characteristic slant angle; and with the pixel rows in their original image position, shifting said pixel rows by the amount of said angular difference, thereby to create an image of said handwritten script that has its characteristic slant angle removed. - View Dependent Claims (2, 3, 4, 5)
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6. Apparatus for normalizing the characteristic slant angle in original handwritten word or number script, comprising:
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means for generating a pixel map of said script, with said script image aligned on said map in a direction substantially parallel to the horizontal axis of said pixel map; said map comprising vertical columns and horizontal rows of dark and white pixels, said dark pixels displaying the script of said word or number, and said display exhibiting said characteristic script slant angle relative to said vertical columns; means for moving said rows of pixels thereby to generate a first altered script image having a first slant angle; means for calculating the total number of dark pixels in said first altered image; means for calculating the number of dark pixels in each said vertical column of said first altered image; means for calculating the proportion of dark pixels in each column relative to said total dark pixels in said first altered image; means for computing the entropy value of said first altered image; means for storing said computed entropy value and its associated first slant angle; means for successively repositioning said rows of pixels thereby to generate a succession of further altered script images, each of said last-named images having a different slant angle; means for computing and storing the entropy values and the respective associated slant angle values for each said further altered image; means for determining the angular difference between that slant angle associated with the minimum entropy value and the characteristic slant angle; and with the pixel rows in their original image position, means for shifting said pixel rows by the amount of said angular difference, thereby to create an image of said handwritten script that has its characteristic slant angle removed. - View Dependent Claims (7)
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Specification