Method and apparatus for recognizing code

• US 7,764,835 B2
• Filed: 05/03/2005
• Issued: 07/27/2010
• Est. Priority Date: 04/15/2003
• Status: Active Grant

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Takakura, Hiroyuki, Noda, Tsugio, Chiba, Hirotaka, Yamaguchi, Nobuyasu
• Primary Examiner(s): Do; Anh Hong
• Application Number:
  US11/119,782
• Publication Number:
  US 20050194445A1
• Time in Patent Office: 1,911 Days
• Field of Search: 382/181, 382/196, 382/197, 382/199, 382/118, 382/313, 382/312, 382/168, 348/207.1, 348/231.3, 348/333.02, 235/462.25, 235/462.09, 235/462.24, 235/3.1, 235/462.1
• US Class Current: 382/168
• CPC Class Codes: G06K 7/10544 by scanning of the records by radiation in the optical part of the electromagnetic spectrum
• CPC Class Codes: G06K 7/14 using light without selection of wavelength, e.g. sensing reflected white light G06K7/10831 - G06K7/1097 take precedence
• CPC Class Codes: G06K 7/1473 error correction
• CPC Class Codes: G06K 7/1478 adapting the threshold for pixels in a CMOS or CCD pixel sensor for black and white recognition
• CPC Class Codes: H04N 1/403 Discrimination between the two tones in the picture signal of a two-tone original

Abstract

When it is determined whether the color of each cell of an image is black or white from the gradation value of each cell, the determination is made by comparison of the gradation level of the cell with a threshold if the gradation level is sufficiently close to that of black or white. In contrast, if the gradation value of the cell is within a gray zone, the color of the cell is determined from the colors of the cells adjacent to the cell of interest. That is, if the gradation value of the cell is gray and the colors of the adjacent cells are all black, the color of the cell is determined to be white; and conversely if the colors of all the adjacent cells are white, the color of the cell is determined to be black.

Claims

1. A two-dimensional code recognition method of recognizing a two-dimensional code that is obtained by generating cells from data and is arranged in two dimensions, comprising:

detecting a coordinate of a target cell;

obtaining a gradation value of the detected coordinate;

determining a value of the target cell from the detected gradation value using a processing unit of a portable terminal; and

outputting a codeword corresponding to the value, thereby recognizing the two dimensional code.

2. A two-dimensional code recognition method of recognizing a two-dimensional code that is obtained by generating cells from data and is arranged in two dimensions, comprising:

obtaining a gradation value of a target cell;

preparing a histogram by obtaining a frequency of a gradation value of an image;

obtaining a first gradation value that is equal to or greater than a predetermined value and is present on a light side of the histogram;

obtaining a second gradation value that is equal to or greater than a predetermined value and is present on a dark side of the histogram;

setting an intermediate value of the obtained first and second gradation values as a threshold;

comparing the gradation value of the target cell with the threshold and determining a type of the target cell using a processing unit of a portable terminal; and

outputting a corresponding codeword, thereby recognizing the two dimensional code.

3. The two-dimensional code recognition method according to claim 2, wherein in respect to the threshold detected in the histogram preparation and the threshold value detection, the cell determination is performed only for a cell that is present in a predetermined threshold range between a predetermined gradation value on the light side and that on the dark side including the threshold itself.

4. A two-dimensional code recognition method, comprising:

comparing a gradation value of a target cell with that of an adjacent cell;

determining a value of the target cell based on the gradation value comparison results of adjacent cells using a processing unit of a portable terminal; and

outputting a codeword corresponding to the value thereby recognizing the two dimensional code.

5. The two-dimensional code recognition method according to claim 4, wherein the adjacent cells are four adjacent cells in the X and Y directions.

6. The two-dimensional code recognition method according to claim 4, wherein the adjacent cells are eight adjacent cells in the X and Y directions.

7. The two-dimensional code recognition method according to claim 4, wherein the determining is performed only for a cell a gradation value of which is in the predetermined region range.

8. The two-dimensional code recognition method according to claim 4, wherein the cell value determination selects a cell a gradation value of which is outside the predetermined region range and determines the value of the cell by comparing the selected cell with the threshold.

9. A two-dimensional code recognition method, comprising:

comparing a gradation value of a target cell and that of an adjacent cell;

comparing the gradation value of the adjacent cell with a threshold;

determining a type of an adjacent cell from the comparing;

determining the type of the target cell that is different from that of the adjacent cell in a case where adjacent cells are all of a same type or a predetermined number of adjacent cells are of a same type using a processing unit of a portable terminal; and

outputting a corresponding codeword, thereby recognizing the two dimensional code.

10. A two-dimensional code recognition method of recognizing a two-dimensional code that is obtained by generating cells from data and is arranged in two dimensions, comprising:

detecting a coordinate value of a target cell;

obtaining a gradation value of the detected coordinate;

obtaining frequencies of gradation values of an image and preparing a histogram;

obtaining a threshold from the histogram;

obtaining a predetermined distance from the threshold and setting the predetermined distance from the threshold as a designated region range;

selecting a cell a gradation value of which is within the region range;

selecting a cell a gradation value of which is outside of the region range;

determining a type of the cell selected in the out-region range cell selection based on the comparison results of the gradation value and the threshold using a processing unit of a portable terminal;

detecting a gradation value of a cell adjacent to a target cell among cells selected in the in-region cell selection;

determining a type of the target cell that is different from that of the adjacent cell in a case where all adjacent cells are of a same type;

determining the type of the target cell in comparison with the threshold in a case where all adjacent cells are not of the same type; and

outputting a corresponding codeword, thereby recognizing the two dimensional code.

11. A two-dimensional code boundary recognition method, comprising:

obtaining a frequency of gradation values of an image and preparing a histogram;

determining a black cell by determining a level range region on the dark side using the histogram using a processing unit of a portable terminal; and

detecting a code boundary using a continuous length of a black cell and a non-black cell that are obtained in the black cell determining outputting a corresponding code boundary recognition, thereby recognizing the code boundary.

12. A code recognition apparatus for inputting an image and recognizing a code, comprising:

a portable terminal comprising;

a camera for inputting the image; and

a plurality of pre-processing units for comparing a gradation value of a target cell in the image with that of an adjacent cell and determining a value of the target cell based on the gradation value comparison results of adjacent cells, thereby recognizing the code.

13. The apparatus as recited in claim 12, wherein the pre-processing unit determines whether or not a small region of the image is a two-dimensional code based on one or more values of pixel gradation dispersion, ratio of black pixels to pixels and a number of black and white edges.

14. An apparatus that can be used for code recognition apparatus, comprising:

a portable terminal comprising;

a camera for inputting an image; and

a plurality of pre-processing units for determining whether a code is included or not,

wherein the image is immediately updated in a case where the determination result is negative,

wherein the pre-processing unit determines characteristics of images of a one-dimensional code region and performs recognition processing of a one-dimensional code based on the determination results, and

wherein the pre-processing unit determines whether or not a small region of the image is a one-dimensional code based on one or more values of pixel gradation dispersion, the ratio of black pixels to pixels, a number of black and white edges and line correlation.

15. The apparatus as recited in claim 14, for inputting an image from the camera and recognizing a code, wherein exposure time of the camera does not exceed the period of one frame of the camera.

16. The apparatus as recited in claim 14, wherein the code comprises a bar code.

17. The apparatus as recited in claim 14, wherein the determining determines whether code recognition processing can be performed.

18. An apparatus that can be used for code recognition apparatus, comprising:

a portable terminal comprising;

a camera for inputting an image; and

a plurality of pre-processing units for determining whether a code is included or not,

wherein the image is immediately updated in a case where the determination result is negative,

wherein the pre-processing unit determines characteristics of images of a two-dimensional code region and performs recognition processing of a two dimensional code based on the determination results, and

wherein the pre-processing unit determines whether or not a small region of the image is a two-dimensional code based on one or more values of pixel gradation dispersion, ratio of black pixels to pixels and a number of black and white edges.