Image analysis – Image transformation or preprocessing – Measuring image properties
Reexamination Certificate
2000-06-15
2003-12-30
Mehta, Bhavesh M. (Department: 2625)
Image analysis
Image transformation or preprocessing
Measuring image properties
C382S171000, C382S190000, C382S219000, C382S282000, C358S452000, C358S453000
Reexamination Certificate
active
06671422
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an apparatus and a method for reading a two-dimensional code. More particularly, it relates to an apparatus and a method for detecting the rough position of a two-dimensional code.
BACKGROUND OF THE INVENTION
Two-dimensional codes are used for process control of various parts. For example, labels with two-dimensional codes thereon are attached to parts for hard disks to carry out process control by the part. Further, two-dimensional codes may be formed on substrates of liquid crystal displays such as color filter substrates or array substrates by photolithographic process to carry out process control by the substrate. Process control of a color filter formed on a substrate may also be carried out by forming a two-dimensional code in the vicinity of the color filter.
FIG.
11
(
a
) shows an example of a two-dimensional code. In the example of FIG.
11
(
a
), a two-dimensional code
12
has such a shape that black and white colored cells
36
are arranged in a matrix form. Noise
38
may be included around the two-dimensional code
12
. FIG.
11
(
b
) shows image data
10
including the two-dimensional code
12
captured from a CCD (charge-coupled device) or the like. The two-dimensional code is extracted from this image data
10
to read the data by decoding the cells
36
. To extract the two-dimensional code
12
, it is, first of all, necessary to detect the position of the two-dimensional code
12
.
As a code position detecting method, for example, scanning is performed at predetermined intervals as shown in FIG.
11
(
b
). After the position of the two-dimensional code
12
is detected by the scanning, the code is extracted from the position. The position detecting method as shown in FIG.
11
(
b
) will detect the perimeter of the two-dimensional code
12
. In the detection of such perimeter, when noise such as noise
38
is included in the area of the captured image data
10
, it is difficult to distinguish the perimeter of the two-dimensional code
12
from the perimeter of the noise. Further, it takes considerable time to perform scanning due to lots of scanning lines.
SUMMARY OF THE INVENTION
Therefore, it is an object of the present invention to provide an apparatus and a method for detecting the rough position of a two-dimensional code easily and at high speed. In one aspect of the present invention, an apparatus for detecting the rough position of a two-dimensional code included in image data is provided, which comprises means for detecting gray scale levels of pixels in image data divided into small areas, means for controlling the means for detecting gray scale levels so that the gray scale levels of the pixels on predetermined scanning lines set in the small areas can be detected, subtracting means for determining a difference between gray scale levels of two neighboring pixels which are adjacent to each other or are spaced at a predetermined interval on the scanning lines in the small areas, means for comparing the determined differences in gray scale level with a predetermined value, means for counting the number of the differences in gray scale level which are equal to or greater than the predetermined value, and means for ranking the small areas based upon the count obtained.
The present invention also provides methods for detecting the rough position of a two-dimensional code included in image data, which, in one aspect, comprises the steps of determining a proportion of the two-dimensional code in each of small areas obtained by dividing the image data, and ranking the small areas based upon the proportions obtained.
In another aspect of the present invention, the method for detecting the rough position of a two-dimensional code according to the present invention comprises the steps of determining a proportion of the two-dimensional code in each of small areas obtained by dividing each of medium areas obtained by the division of the image data, ranking the small areas for each medium area based upon the proportions obtained, and determining the ranking of all the small areas on the basis of the ranking of the small areas determined for each medium area.
REFERENCES:
patent: 5194966 (1993-03-01), Quardt et al.
patent: 5260807 (1993-11-01), Tai
patent: 5519509 (1996-05-01), Hikosaka et al.
patent: 5604605 (1997-02-01), Moolenaar
patent: 5818971 (1998-10-01), Moolenaar et al.
patent: 5835687 (1998-11-01), Brown et al.
patent: 5848198 (1998-12-01), Penn
patent: 5979763 (1999-11-01), Wang et al.
Beck Thomas A.
Herzberg Louis P.
International Business Machine Corporation
Kassa Yosef
Mehta Bhavesh M.
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