Method and apparatus for detecting and decoding bar code symbols using two-dimensional digital pixel images
AssigneeUnited Parcel Service of America, Inc.
InventorsLuis Figarella, Mihael Klancnik
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Abstract
A system for detecting a bar code symbol receives a two-dimensional image containing the symbol, where the system has no a priori knowledge of the orientation of the symbol in the image. The system scans the image in one dimension to locate a quiet zone for the symbol and searches the image in one dimension to identify a start/stop character of the symbol.
Claims42
A method for detecting a bar code symbol with a bar code symbol reader, comprising the steps of:
- (a) receiving a two-dimensional image containing said symbol, wherein said bar code symbol reader has no a priori knowledge of the orientation of said symbol in said image;
- (b) scanning said image in one dimension to locate a quiet zone for said symbol;
- and
- (c) searching said image in one dimension to identify a start/stop character of said symbol using subpixel interpolation.
An apparatus for detecting a bar code symbol, comprising:
- (a) means for receiving a two-dimensional image containing said symbol, wherein said apparatus has no a priori knowledge of the orientation of said symbol in said image;
- (b) scanning means for scanning said image in one dimension to locate a quiet zone for said symbol;
- and
- (c) searching means for searching said image in one dimension to identify a start/stop character of said symbol using subpixel interpolation.
A method for detecting a bar code symbol with a bar code symbol reader, comprising the steps of:
- (a) receiving a two-dimensional image containing said symbol, wherein said bar code symbol reader has no a priori knowledge of the orientation of said symbol in said image;
- (b) scanning said image in one dimension to locate a quiet zone for said symbol;
- and
- (c) searching said image in one dimension to identify a start/stop character of said symbol, wherein said scanning is performed at low resolution and said searching is performed at high resolution.
An apparatus for detecting a bar code symbol, comprising:
- (a) means for receiving a two-dimensional image containing said symbol, wherein said apparatus has no a priori knowledge of the orientation of said symbol in said image;
- (b) scanning means for scanning said image in one dimension to locate a quiet zone for said symbol;
- and
- (c) searching means for searching said image in one dimension to identify a start/stop character of said symbol, wherein said scanning means scans at low resolution and said searching means searches at high resolution.
A method for detecting a bar code symbol with a bar code symbol reader, comprising the steps of:
- (a) receiving a two-dimensional image containing said symbol, wherein said bar code symbol reader has no a priori knowledge of the orientation of said symbol in said image;
- (b) scanning said image in one dimension to locate a quiet zone for said symbol;
- (c) searching said image in one dimension to identify a start/stop character of said symbol;
- (d) locating first and second corners of said symbol;
- (e) scanning said image to locate a second quiet zone for said symbol;
- (f) searching said image to identify a second start/stop character of said symbol;
- and
- (g) locating third and fourth corners of said symbol.
An apparatus for detecting a bar code symbol, comprising:
- (a) means for receiving a two-dimensional image containing said symbol, wherein said apparatus has no a priori knowledge of the orientation of said symbol in said image;
- (b) scanning means for scanning said image in one dimension to locate a quiet zone for said symbol;
- (c) searching means for searching said image in one dimension to identify a start/stop character of said symbol;
- (d) means for locating first and second corners of said symbol;
- (e) means for scanning said image to locate a second quiet zone for said symbol;
- (f) means for searching said image to identify a second start/stop character of said symbol;
- and
- (g) means for locating third and fourth corners of said symbol.
Dependencies are inferred from the claim text.