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Character Contour Measurements From Character Images Stored in Run-Length Form

IP.com Disclosure Number: IPCOM000041930D
Original Publication Date: 1984-Mar-01
Included in the Prior Art Database: 2005-Feb-03
Document File: 3 page(s) / 56K

Publishing Venue

IBM

Related People

Bednar, GM: AUTHOR [+3]

Abstract

Contour attributes of a character image to be automatically recognized are extracted directly from the image stored in run-length form by simple logical operations comparing run lengths from adjacent scan lines. Elemental attributes thus collected can be used directly for recognition or can be logically combined into shape classifications of greater significance. The images of characters to be recognized are segmented from other image data, normalized in size to fit a standard frame, and converted into an array of horizontal run lengths.

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Character Contour Measurements From Character Images Stored in Run- Length Form

Contour attributes of a character image to be automatically recognized are extracted directly from the image stored in run-length form by simple logical operations comparing run lengths from adjacent scan lines. Elemental attributes thus collected can be used directly for recognition or can be logically combined into shape classifications of greater significance. The images of characters to be recognized are segmented from other image data, normalized in size to fit a standard frame, and converted into an array of horizontal run lengths. The character "8", as shown in normalized full image form, would be expressed as an array of run lengths, beginning at its top left quarter as three white, six black, two white, one black, one white for the first horizontal row, and one white, four black, three white, one black, two white, one black and one white for the second row, and so forth. The run lengths could also be abstracted to a small set of length possibilities, such as long, medium and short. Elemental contour measurements are achieved by comparing the first run length of a scan line with the first run length of the immediately preceding scan line to determine simple relationships, such as greater than, equal to, or less than. It is also useful to provide for a determination that the relative magnitudes of adjacent run lengths differ by such a large amount that a discontinuity or break in the profile is indicated. For the left side of a character image, these measurements may be expressed as L (angle left) where the adjacent run lengths indicate the contour moving to the left, i.e., second run length less than the first run length; the V (vertical) where the adjacent run lengths are equal; R (angle right) where the second run length is greater than the first run length, indicating the contour moving downwardly to the right; B1 (break left) where the second run length is greater than or less than the adjacent run length by more than some specified threshold; and B2 (break right) where the second run length is less than the adjacent run length by more than the threshold. Similar notation can be applied to the run lengths defining the right profile of the character image. The results of all comparisons may be stored as a binary descriptor or vector, indicating by bit location the elemental contour shapes of the charact...