JP3974312B2 - Image processing device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image forming apparatus having a function of preventing counterfeiting such as banknotes, and more particularly to an image processing apparatus for adding pattern tracking information with yellow toner on an image.
[0002]
[Prior art]
In recent years, a high-quality digital color copier that provides a faithful copy of a manuscript image has been put into practical use, and there is a risk that banknotes or securities will be easily copied and forged. Forgery prevention means to cope with this, it is determined whether or not the document set on the document table is copy-prohibited and the copying operation is stopped or normal copying cannot be performed. Possible function. However, storing all these features for manuscripts such as banknotes, securities, TCs, checks, and official documents all over the world, and prohibiting copying by pattern matching, storage capacity, processing time, new bills It is practically impossible due to countermeasures.
[0003]
Therefore, copying itself cannot be prohibited, but a special code (tracking information) that is not normally visible is written on the copied copy itself, and the manufacturer's model name, serial number, date and time of copying, Management card No. There are copiers that have a function to specify a part of them. For example, as shown in FIG. 1, the tracking information is represented by an arrangement of small yellow dots (for example, consisting of one pixel) in a predetermined block, and the block on which the tracking information is written is a copy sheet on which a document image is copied. There is a technology to write in. The identification of the product name and serial number is executed by extracting the arrangement of dots written in the block. Since the yellow dots are written on the document table, it is not possible to know where illegal copy-prohibited documents (banknotes, stamps, revenue stamps, securities, etc.) are placed. Type in. Also, it is possible to cut out a part of the copy paper, and the size of the block in which tracking information is written (DOTD) so that it can be analyzed when small items such as stamps and income stamps are cut out and used. It is desirable to make (× DOTL) as small as possible.
[0004]
[Problems to be solved by the invention]
The encrypted yellow dots as shown in FIG. 1 are difficult to visualize, but if the density is high or a large number of dots are written on the entire surface, the yellow is conspicuous and an image defect occurs. In addition, even if it is difficult to see with yellow dots alone, they may be visualized by mixing with other color toners by subtractive kon-color. In particular, in a binarized image such as an area gradation (dither method), it is difficult to read a density difference and difficult to read. However, if the dot size of the tracking information is reduced due to these defects, it becomes difficult to read the tracking information for the original purpose, and if it is increased, the tracking information becomes conspicuous in a low density image.
[0005]
An object of the present invention is to provide an image processing apparatus capable of writing more appropriate tracking information.
[0006]
[Means for Solving the Problems]
In order to solve the above-described problems, the present invention provides an image processing apparatus that adds tracking information to an output image with yellow toner, based on the density of input image data (XI), XR = a * XI + n (XR; calculation result, a; arbitrary , N: addition value), and the calculation result (XR) is compared with the threshold value (TH). When XR ≦ TH, XR is obtained, and when XR> TH, TH is obtained. ), And an overflow signal that outputs an OF signal that is an L signal when XR ≦ TH and an H signal when XR> TH. A pattern for generating a tracking pattern (ONDOT signal) to be added to an input image based on output means, a memory for holding tracking information and information necessary for the calculation, and tracking information data held in the memory The number of pixels when addition is not permitted (L signal) among the OF signals output from the overflow signal output means when the ONDOT signal generated by the generation means and the pattern generation means is permitted to add (H signal). DATESEL signal generation means for outputting a DATESEL signal that counts and outputs an H signal when this number is less than the predetermined count number N and an L signal when the predetermined count number N is exceeded, and when the DATESEL signal is an H signal Output data data output means for outputting output image data (XO) while switching the input image data (XI) with a selector when the DATESEL signal is an L signal for the post-computation data (XC). An image processing device is used.
[0007]
[Action]
The image processing apparatus of the present invention adds tracking information with a large dot size when there are many pixels with high density near the position where the tracking information for image data is added, and tracking information with small dot sizes when there are few pixels with high density. By adding, tracking information that can be discriminated without impairing image quality is added.
[0008]
【Example】
A block diagram of the present invention is shown in FIG. As shown in the figure, the image processing apparatus of the present case includes an arithmetic processing unit 1, a memory 2, an overflow signal output means 3, a pattern generation means 4, a DATESEL signal generation means 5, and a selector 6.
[0009]
Calculation and data processing in each of the above configurations will be described with reference to FIGS. The calculation processing means 1 calculates the calculation result (XR) used in the overflow signal output means 3 and post-calculation data (XC) that becomes the image density when tracking information is added based on the input image data (XI). . First, the XC output condition and the calculation result (XR) used in the subsequent overflow signal output means 3 perform XR = a * XI + n (a: calculation coefficient, n: addition value). Next, the calculation result (XR) is compared with the threshold value (TH). When XR ≦ TH, XC = XR is set, and when XR> TH, post-calculation data (XC) is output with XC = TH. As shown here, the post-computation data XC output is obtained by adding a computation coefficient a to the input image XI and adding an addition value n to produce a density difference with respect to the input image data. As shown in FIG. 3, in this embodiment, binarized data is targeted, and a = arbitrary, n = 1, and TH = 1. Therefore, when XI = 0, XR = 1, and when XI = 1, X R = a + 1 > TH, and XC = 1 regardless of XI . These calculation coefficients a, additional value n, the threshold TH is used in the calculation are stored in the memory.
[0010]
The overflow signal output means 3, the comparison calculation result (XR) threshold (TH), when the XR ≦ TH L signal, when the X R> TH outputs the OF signal which becomes H signal. As shown in FIG. 3, since the binarized data is used in this embodiment, an OF signal that is an L signal when the input image data is 0 and an H signal when the input image data is 1 is output as described above. .
[0011]
The pattern generation means 4 outputs an ODOT signal that becomes an H signal when an area to which tracking information is added and an L signal when the area is not. FIG. 4 shows an image of this ONDOT signal. Here, the addition of tracking information is permitted when the H signal is output.
[0012]
The DATESEL signal generation unit 5 is configured to determine the OF when the NDOT signal is at the H level based on the input image data XI, the ONDOT signal from the pattern generation unit 4, and the OF signal from the overflow signal output unit 3. The L level pixels of the signal are counted, and a DATESEL signal that outputs the H level is output until this reaches a predetermined count number N set in advance. Figure in this embodiment shown in 5, is set to a predetermined count number N = 3, darker pixels ONDOT signal is input image data XI at the first additional permission region included black pixels 5/8 Therefore, the DATESEL signal is a signal having the full length of the addition permission area, and when the next ONDOT signal is the addition permission area, the input image data XI is the predetermined count N = 3 when it is the fourth pixel. Therefore, the DATESEL signal is the fourth signal from the front of the addition permission area. Here, the width of the ONDOT signal addition permission area is 8 pixels wide, and since the DATESEL signal is output in real time, when the low density pixels are concentrated in the first half, the dark pixels are concentrated later. In contrast, when dark pixels are concentrated in the first half, a long DATESEL signal is generated even if low density pixels are concentrated later. However, the relationship with the input image data to which data is added is as follows. This is not a problem because it is short for low concentrations and long for high concentrations. As another method, the length of the DATESEL signal may be changed according to the ratio of the OF signal when the data is once held in the register and the ONDOT signal is in the addition permission area.
[0013]
Finally, in the selector 6, the post-computation data XC is output when the DATESEL signal is at the H level, and the output image data XO is switched to output the input image data as it is when the DATESEL signal is at the L level. . As a result, when the tracking information is added to the area where the high density pixels of the input image data XI are concentrated, the additional information is wide. When the low density is concentrated, the additional information is narrow.
[0014]
【The invention's effect】
If the present invention is used, wide tracking information is added where high density pixels are concentrated, and narrow tracking information is added where low density pixels are concentrated. Tracking information that can be easily identified can be added without damaging the image and even at a high density. This is particularly effective for images expressed by area gradation. In addition, in the present embodiment, the concentration XC of the tracking information is expressed by XC = a * XI + n and TH, but the same effect can be obtained by using other arithmetic expressions.
[Brief description of the drawings]
FIG. 1 is an image of tracking information in the prior art.
FIG. 2 is a block diagram of an image processing apparatus employing the present invention.
FIG. 3 is an image diagram in which an arithmetic processing unit of an image processing apparatus employing the present invention outputs an arithmetic result and post-computation data, and an overflow signal output unit outputs an OF signal.
FIG. 4 is an image diagram in which a pattern generation unit of an image processing apparatus adopting the present invention outputs an ONDOT signal.
FIG. 5 is an image diagram of generation of a DATESEL signal of an image processing apparatus employing the present invention.
FIG. 6 is an explanatory diagram of a method for selecting output image data of an image processing apparatus employing the present invention.
[Explanation of symbols]
1; arithmetic processing means 2; memory 3; overflow signal output means 4; pattern generation means 5; DATESEL signal generation means 6;

Claims (1)

In an image processing apparatus that adds tracking information to binarized density data of yellow toner , XR = a * XI + n (XR: calculation result, a: arbitrary, n: added value) is calculated from the density of input image data (XI). Computation processing means for performing computation and comparing the computation result (XR) with a threshold value (TH), and outputting post-computation data (XC) that is XR when XR ≦ TH, and TH when XR> TH. And an overflow signal output means for outputting an OF signal that is an L signal when XR ≦ TH and an H signal when XR> TH, and tracking information and Based on the tracking information data held in the memory, the memory that holds information necessary for the calculation, and the NDOT signal that becomes the L signal in the area to which the tracking information is added and the L signal in the other area output A pattern generating means that, pixel when the ONDOT signal additional permission that is generated by the pattern generating means added disallowed Of (H signal) OF signal output from said overflow signal output means when the (L signal) DATESEL signal generation means for outputting a DATESEL signal that counts the number and outputs a DATESEL signal that becomes an L signal when this number is less than the predetermined count number N, and the DATESEL signal is an H signal Output image data output means for outputting the output image data (XO) while switching the input image data (XI) with a selector when the DATESEL signal is an L signal. An image processing apparatus.

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