JP2000295470A - Image output device - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To prevent forgery of a rotated image. SOLUTION: m generated by a matrix unit 503
The pixel data for one round of each of a plurality of concentric annular regions is extracted from the input image data of × n pixels, and is compared with the reference data while being shifted clockwise by one pixel by the shift register 601 and matched. The number of pixels obtained is added to the adder 605.
And the result is compared with the threshold value by the comparator 605.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image output device for preventing counterfeiting of images of bills, securities and the like input from outside.

[0002]

2. Description of the Related Art Generally, a color copying machine has a function of preventing forgery by storing an image read from a scanner in a frame memory and comparing the image with a reference image such as bills and securities. It has been known. However, since a color printer does not have a frame memory unlike a color copying machine, the above function cannot be realized, and adding a frame memory increases the cost and reduces the printing speed.

In order to prevent forgery by reducing the memory capacity, for example, Japanese Patent Application Laid-Open No. 7-47717 discloses a method in which a color image signal input from the outside is buffered and divided into a plurality of signals. There has been proposed a method for preventing forgery by parameterizing image features and comparing the parameter with a reference parameter.

[0004]

However, in recent years,
A lot of software for editing image data on computers has become available, making it easy to enlarge, reduce, and rotate image data. Therefore, in the above conventional example, there is a problem that it is difficult to prevent forgery of the image rotated in this way.

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above-described problems of the related art, and has as its object to provide a color image output apparatus that can prevent forgery of a rotated image.

[0006]

According to a first aspect of the present invention, there is provided an extracting means for extracting pixel data of a plurality of concentric annular regions each having a width of about one pixel from an input image. 1 of each of the plurality of annular regions extracted by
Means for identifying whether or not the input image is a forgery prohibition object by comparing the pixel data of the circumference with the reference pixel data while shifting the pixel data clockwise or counterclockwise for each pixel. It is characterized by.

A second means is that, in the first means, if the identification means compares the pixel data of the annular area with reference pixel data and the number of matched pixels is equal to or greater than a threshold value, the input image is subject to forgery prohibition. Is determined.

The third means further comprises a reducing means for reducing the input image in the first and second means, and a binarizing means for binarizing the image reduced by the reducing means. Is characterized in that a specific region is extracted from the image data binarized by the binarizing means, and pixel data of a plurality of concentric annular regions is extracted from the specific region.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. 1 is a schematic diagram showing a general color printer, FIG. 2 is an explanatory diagram schematically showing recognition marks such as bills, FIG. 3 is an explanatory diagram showing a method of reducing an input image, and FIG. 3 is rotated. Explanatory diagram showing an input image and a reference image,
4 is an explanatory diagram showing an extraction region of an input image, FIG. 5 is a block diagram showing an embodiment of a color image output device according to the present invention, FIG. 6 is a block diagram showing a matrix section of FIG. 5 in detail, and FIG. FIG. 8 is an explanatory diagram showing the pixel positions in the extraction region, FIG. 8 is an explanatory diagram showing the pixel extraction order in FIG. 7, FIG. 9 is a block diagram showing the identification unit in FIG. 5 in detail, and FIG. 10 shows the determination unit in FIG. Block diagram, FIG. 11 is an explanatory diagram showing a rotated input image and a reference image, FIG. 12 is an explanatory diagram comparing each pixel of the input image and the reference image of FIG. 11, and FIG. FIG. 11 is an explanatory diagram showing a procedure for comparing with a reference image while shifting in a circumferential direction.

In the color printer shown in FIG. 1, the surface of the photoreceptor drum 1 makes one rotation, is uniformly charged by the charger 2, and then a K, C, M or Y latent image is selectively formed. Then, the latent image is developed by the developing drum 3, and the respective toner images are superimposed on the transfer drum 4 to form a color image. Then, the color image on the transfer drum 4 is transferred onto the sheet P, and the color image on the sheet P is fixed by the fixing roller 5.

As shown in FIG. 2, the characters and figures on the paper P are dots of any width "●" (binary image = 1) arranged on a grid of, for example, 300 dpi for each color.
It is represented by “○” (binary image = 0). Here, FIG. 2 schematically shows a character “a” for explaining a recognition mark used in a bill or the like, and the character “a” is edited by computer application software.
It is rotated 80 °.

The recognition mark of a bill or the like is a red seal or a mark formed by imprinting, but the relative angle of the recognition mark on the mount such as a bill is not constant. Further, as described above, when a banknote or the like is read into a computer or the like as image data, there is a possibility that the banknote or the like is read in an obliquely inclined state, or is rotated 180 ° after the reading. Therefore, the recognition mark may not be at the original angle.

Therefore, in the present embodiment, as shown in FIG. 2, the features of the rotated recognition mark image are recognized to detect whether or not the image is a forgery prohibition image such as a bill. Further, recognition marks such as banknotes are usually extracted by focusing on points surrounded by circles. In this embodiment, the image shown in FIG. 2 is reduced in the main scanning direction and the sub-scanning direction to obtain a dot image as shown in FIG. Next, as shown in FIG. 3 (2), the reduced image is a ring-shaped area “0” having a width of 1 to 2 pixels as a center A, and a ring-shaped area outside the circular area “0” and having a width of 1 pixel. “1” and each pixel data in the annular area “2” to which is further outside the annular area “1” and has a width of 1 to 2 pixels are registered in advance while shifting clockwise by one pixel. Compare with image data. FIG. 4 shows only these areas “0”, “1”, and “2”.

Next, this embodiment will be described in detail with reference to FIG. In FIG. 5, input image data is, for example, 8 bits (0 to 255) for each of K, C, M, or Y;
The resolution is 300 dpi, and the 縮小 reduction unit 501 reduces the input image data in the main scanning direction and the sub scanning direction as shown in FIG. Here, by changing the reduction rate according to the size of the internal memory, the processing time, the priority of recognition, and the like, the system can be configured for general use. The subsequent binarization unit 502 binarizes the image data reduced by the 縮小 reduction unit 501.

As shown in detail in FIG. 6, the following matrix section 503 generates a matrix of m pixels in the main scanning direction × n lines in the sub scanning direction based on the data binarized by the binarization section 502. It has a line memory 520 for n-1 lines and a shift register for m × n pixels. The subsequent pattern matching unit 504 compares the matrix data with the circular reference binary image data stored in the circular pattern memory 505 in advance, and determines the degree of conformity.
It is determined whether or not the input image data has a circular pattern on the outer periphery. If it is determined that the input image data has a certain degree of matching, the fact is output to the identification unit 506.

Upon receiving the above notification, the identification unit 506 receives the matrix data generated by the matrix unit 503 and the K, C, M,
Y reference pattern data 508, 509, 510, 51
Compare one of the ones. In this case, a comparison is made with the reference pattern for each of the annular areas “0”, “1”, “2” to the center A of the matrix data.

FIG. 7B shows the addresses of the annular areas "0", "1", and "2" shown in FIG. 7A. FIG. 8A shows the annular regions “0”, “1”,
FIG. 8 shows pixel positions in a state where “2” is individually extracted.
(B) shows the annular regions “0”, “1”,
Each pixel in “2” is extracted in the clockwise direction starting from the pixel indicated by ↓ and starting from the pixel indicated by ↑, and is extracted in a closed loop with the pixel indicated by 終 as the end. That is, for the annular area “2”, the start pixel “1f” to the “1f”
g ”,“ 2g ”and so on in the clockwise direction of the starting pixel“ 1 ”.
44 pixels up to the end pixel “2f” under “f” are extracted. Similarly, for the annular area “1”, the start pixel “3”
From "g" to the end pixel "3g" on the left side thereof is extracted by a closed loop, and for the annular area "0", from the start pixel "4g" to the end pixel "4f" on the left side thereof is extracted by a closed loop.

As shown in detail in FIG.
In this way, the annular area “0” extracted in the closed loop,
It has a shift register 601 for shifting each pixel data of "1" and "2" for each pixel, and this shift register 601 has a number of stages 2N which is twice the number N of extracted pixels. Then, as shown in FIG. 10, the exclusive OR gate 604 detects a mismatch between the input pixel data and the reference pixel data for each shift (mismatch = 1, match = 0), and then matches each detection signal by the inverter 604. = 1, mismatch = 0, and the sum of the matching signals is added to the adder 605.
Is detected by

Here, FIG. 11A shows a state where the input image “a” is rotated by 180 °, and FIG. 11B shows a state where the reference image is at a normal angle with respect to the input image “a”. Then, these images are combined with the starting pixel “1” of the annular area “2”.
f ”to“ 1g ”,“ 2g ”, and so on, until the lower end pixel“ 2f ”in the clockwise direction is extracted.
2 (A) and (B). As is apparent from the figure, since the input image “a” is rotated by 180 °, both look like completely different pixel patterns, and the number of matching pixels is small. Therefore, as shown in FIG. 13, when the input image is shifted by one pixel, that is, rotated by one pixel and compared by rotating by 180 °, all of the 44 pixels match. However, since all of the 44 pixels rarely coincide, the comparator 6 shown in FIG.
By comparing the number of matching pixels with a threshold value (comparison parameter) for determining whether or not the pixel is a forgery prohibition target, the determination can be made accurately. The comparison parameter is appropriately selected according to the complexity and the pixel density of the target image. In addition, this determination is made as shown in FIG.
M, Y reference pattern data 508, 509, 51
It is determined by comparing with 0 and 511.

The determination of the specific image is made at least by the final color print output step, and the final color, for example, uniform density data is overlapped and superimposed over the entire surface of the image printed and output. The specific image recognized by performing such a measure as not to be an output image. However, when it is determined that the image is the specific image after the printing process of the final color is completed, the uniform density data cannot be overlapped because the printing process is performed in a sequential process. Therefore, for example, it is possible to prevent the print output by stopping the rotation of the fixing roller of the fixing unit, access the developed image data again, and write the overlapped uniform density data. Thus, normal print output can be prevented. Therefore, according to the present embodiment, whether the input color image data is an image read at any rotation angle, whether the image data has the characteristics of the image to be forged is prevented. A simple circuit to examine and prevent counterfeit prohibited image data before it is printed out in perfect form,
It can be realized at low cost.

Here, in general, the data value of each pixel of each color component of the color image data has at least two or more gradation levels. For a binary image, a feature is extracted to detect a specific image. In such a case, the image data can be used as it is. However, in order to detect a specific image, a multi-valued image must be binarized using a threshold to extract features.

FIG. 14 shows the density distribution of a certain color component of a multi-valued color image in which one color component of one pixel is expressed by 8 bits (= 256 gradations). As shown in FIG. The data is generally distributed with a certain spread for density values from 0 to 255. However, if a similar density distribution is considered for a certain characteristic image, the distribution may be a characteristic density distribution representing the characteristics of the image. As described above, it is possible to express the features of an image by focusing on the density in a certain closed section. Therefore, in this embodiment, the range of the data values a to b in FIG. 14 is set to “1” and the data values of the other parts are set to “0” for each pixel of each color component of the input color image data. Binarization is performed on the input image data. Therefore, the image data reduced by the 縮小 reduction unit 501 is converted into an appropriate threshold value or range for each color component in consideration of the color of a specific image serving as a reference for forgery detection. The image data is binarized. However, when an actual color print output is performed, it is a matter of course that a color image is output as it is without binarization.

[0023]

As described above, according to the first aspect of the present invention, pixel data for one round of each of a plurality of concentric annular regions is clockwise or counterclockwise for each pixel. By comparing the input image with the reference pixel data while shifting, it is determined whether the input image is a forgery prohibition target.
Forgery of the rotated image can be prevented.

According to the second aspect of the present invention, when the number of matched pixels is equal to or greater than the threshold as compared with the pixel data of the annular area and the reference pixel data, the input image is determined to be a forgery prohibition target. Even if the pixel data does not match, forgery of the rotated image can be prevented.

According to the third aspect of the present invention, the input image is reduced and binarized, a specific region is extracted from the binarized image data, and pixel data of a plurality of concentric annular regions is extracted from the specific region. Is extracted, and forgery of the rotated image can be prevented with a small memory capacity.

[Brief description of the drawings]

FIG. 1 is a configuration diagram schematically showing a general color printer.

FIG. 2 is an explanatory view schematically showing a recognition mark such as a bill.

FIG. 3 is an explanatory diagram showing a method of reducing an input image.

FIG. 4 is an explanatory diagram showing an extraction area of an input image.

FIG. 5 is a block diagram showing one embodiment of a color image output device according to the present invention.

FIG. 6 is a block diagram showing a matrix unit of FIG. 5 in detail.

FIG. 7 is an explanatory diagram showing pixel positions of an extraction area.

FIG. 8 is an explanatory diagram showing a pixel extraction order in FIG. 7;

FIG. 9 is a block diagram illustrating an identification unit of FIG. 5 in detail;

FIG. 10 is a block diagram illustrating a determination unit of FIG. 9 in detail;

FIG. 11 is an explanatory diagram showing a rotated input image and a reference image.

FIG. 12 is an explanatory diagram comparing each pixel of the input image and the reference image of FIG. 11;

FIG. 13 is an explanatory diagram showing a procedure for comparing pixels of the input image in FIG. 12 with a reference image while shifting the pixels in a clockwise direction.

FIG. 14 is an explanatory diagram showing a density distribution of a certain color component.

[Explanation of symbols]

 501 1/2 reduction section 502 binarization section 503 matrix section 504 pattern matching section 505 circular pattern memory 506 identification section 507 selector 508 K reference pattern data 509 C reference pattern data 510 M reference pattern data 511 Y reference pattern Data 601 Shift register 602 Judgment unit 603 Exclusive OR gate 604 Inverter 605 Adder 606 Comparator

 ──────────────────────────────────────────────────続 き Continuing on the front page F term (reference) 3E041 AA01 AA02 BA11 BC05 CA10 CB02 CB08 DB01 5C077 LL14 MP08 PP20 PP22 PP33 PP38 PP43 PP55 PP68 PQ22 PQ24 RR02 RR14 TT03 TT06 5L096 AA02 AA06 BA03 BA18 DA17 EA03 EA03 EA03 HA08 9A001 BB02 BB03 BB04 EE05 HH21 HH24 HH28 HH31 JJ35 JJ64 KK31 KK42 LL03

Claims (3)

[Claims] 1. An extracting means for extracting pixel data of a plurality of concentric annular regions each having a width of approximately one pixel from an input image, and pixel data for one round of each of the plurality of annular regions extracted by the extracting unit. Means for determining whether an input image is a forgery prohibition target by comparing the input image with reference pixel data while shifting the input image clockwise or counterclockwise for each pixel. 2. The method according to claim 1, wherein the discriminating unit determines that the input image is a forgery prohibition target when the number of pixels that match the pixel data of the annular area and the reference pixel data is equal to or greater than a threshold value. Item 2. The image output device according to Item 1. 3. The image processing apparatus according to claim 1, further comprising: a reducing unit configured to reduce an input image, and a binarizing unit configured to binarize the image reduced by the reducing unit, wherein the extracting unit performs binarization by the binarizing unit. 3. The image output apparatus according to claim 1, wherein a specific area is extracted from the extracted image data, and pixel data of a plurality of concentric annular areas is extracted from the specific area.