Image analysis – Color image processing – Pattern recognition or classification using color
Reexamination Certificate
1997-04-07
2001-02-13
Chang, Jon (Department: 2723)
Image analysis
Color image processing
Pattern recognition or classification using color
C382S135000, C382S317000, C399S366000
Reexamination Certificate
active
06188787
ABSTRACT:
FIELD OF THE INVENTION
The invention is directed to an image recognition method and device that prevents the reading or printing of a document that should not be reproduced. Such a document could be a bank note, a stock certificate, or contain classified material. The invention is also directed to a copier or scanner in which this method and device are employed.
BACKGROUND OF THE INVENTION
With the development in recent years of such copying devices as full-color copiers, the quality of the reproduced image has reached the level at which the reproduction cannot be distinguished from the original image (i.e., the document) with the naked eye. This sort of faithful reproduction has become easy to obtain. The development of high-quality copiers has increased the risk that copiers will be used for an improper purpose. Documents which should not be reproduced, such as bank notes or stock certificates, might be copied. Classified documents might be copied and leaked. Various devices have been developed to address this risk.
One such device is the image processor described in the Japanese Patent Publication of Patent 2-210591. This processor works in the following way. The location of the characteristic portion of the bank note or other nonreproducible item (in the patent report, the red seal) is specified. The image data associated with the specified region are compared with previously recorded characteristics (i.e., with a reference pattern). From the goodness of fit of the two patterns (i.e., their degree of resemblance to each other) a determination is made as to whether the document being processed is one which may not be reproduced. If it is determined that this is a nonreproducible document, specified processing is executed to prevent it from being copied. This may be accomplished by interrupting the processing being executed by the copier, printing out a black screen, or printing out the original image with the word “copy” superimposed on it.
Existing image processors capable of detecting nonreproducible documents and preventing their reproduction often attempt to make their detection function fool proof in order to reliably prevent counterfeiting. To this end the threshold value used to make a determination is lowered to the point where some documents which should be reproduced are prohibited. When this happens, the essential function of the copier, which is to reproduce the document with precisely the same dimensions or at a specified magnification, will not be carried out. This has a deleterious impact on the ordinary, law-abiding user.
To prevent such situations from arising, the threshold value used to determine recognition can be set higher. In this case only items identical to the recorded characteristic (i.e., to the reference pattern) or very closely resembling it will be detected. A document that resembles the reference pattern (i.e., a document whose reproduction is not prohibited) will be permitted to be copied. However, if the reference mark is defaced, either on purpose or accidentally, so the degree of resemblance of the mark to the reference pattern is reduced, the mark will not be detected using the higher threshold, and copying will be permitted. For example, someone might cover the entire pattern on a document with black or some other color. If color is one of the criterion used for determination, the document, which now has a different color, will not be recognized as containing the item to be detected, and copying will be permitted.
This situation is not limited to copy machines, but also occurs with scanners and various other processing devices which read an image.
SUMMARY OF THE INVENTION
The object of the invention is to solve the problem outlined above and to provide an image recognition method and device which reliably detects all nonreproducible documents and whose detection capabilities are not compromised by tampering. In particular, tampering which changes the color of a part of, or all of, the document will not compromise detection. Another object is to provide a copy machine and a scanner in which such a method and device are employed.
In order to achieve the objects stated above, the image recognition method of this invention executes specified image processing with respect to image data obtained from the object under examination. The presence of a given mark, which is the target item to be detected among the image data, is recognized. When a mark is recognized which is a different color from that specified, but which still meets a certain criterion, the image data is recognized as containing the target item to be detected.
The method outlined above can be implemented by an image recognition device which executes specified image processing with respect to image data obtained from the object under examination and recognizes the presence of a given mark, which is the target item to be detected among the image data. This device is equipped with a mark detecting means to detect the specified mark and a different color detection means to detect, with reference to the specified mark, a mark of a different color which meets a certain criterion. The device, therefore, recognizes the image data having a different color mark as a target item.
Ideally, the aforesaid specified criterion should be that any one of the three color components, red (R), green (G) or blue (B), will vary or that any two of the components will vary. The different color could also be black.
Marks of a different color include marks whose color has been entirely changed and marks whose color has been partially changed. A variety of methods may be used to recognize the specified mark by the mark detection means. A reference pattern identical to the mark can be created and the image data may be matched against this reference pattern and the degree of resemblance (i.e., the goodness of fit) obtained. A graduated reference pattern can also be created from the specified pattern and the image data which are read can be averaged (processed to create gradation) and matched against the graduated reference pattern. In one embodiment, instead of the patterns themselves being compared, an appropriate feature count is extracted from the patterns and image recognition is based on this feature count.
The color of the differently colored mark is one likely to be used to deface the pattern. That is to say, the “differently colored mark” referred to in this invention is a mark comprising either partially or entirely of a color likely to be used to deface the pattern.
The mark detection means to detect an undefaced mark and the different color detection means to detect a differently colored mark may be independent of each other, but they may share a common unit to execute the actual recognition processing.
The mark detection means to detect an object mark has a characteristic color extraction block
17
, a component within color extraction unit
10
, which extracts the characteristic color of the mark; memory device
11
; mark detection unit
12
; image extraction unit
13
; matching unit
14
; dictionaries
15
and control unit
16
. The different color detection means to detect a differently colored mark has likely color extraction block
18
, a component within color extraction unit
10
, which extracts a color with which the aforesaid characteristic color is likely to be defaced; memory device
11
; mark detection unit
12
; image excision unit
13
; matching unit
14
; dictionaries
15
and control unit
16
. All components beyond memory device
11
, then, are shared.
The function of recognizing the presence of a specified mark detected by either of the detection devices rests with the OR element
19
in color extraction unit
10
.
The copy machine or scanner of this invention is equipped with one of the image recognition devices described above. With a copy machine, the image data output by the copy machine's image reading device are input in parallel to both the means to convert the image to signals and to the aforesaid image recognition device. With a scanner or printer, the input and ou
Hiraishi Junji
Kinoshita Ikuo
Nakamura Hitoshi
Ohmae Kouichi
Sonoda Shinya
Chang Jon
Dickstein , Shapiro, Morin & Oshinsky, LLP
Omron Corporation
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