JPH04302268A - Image processor - Google Patents

Abstract

PURPOSE:To prevent the malicious use of a copy object by inputting an electric signal corresponding to an original image by an input means and detecting an electric signal corresponding to an invisible image from the inputted electric signal by a detecting means. CONSTITUTION:Color image signals (R, G and B) read by an image scanner 201 are inputted to a specified pattern image correcting circuit 101. At the specified pattern correcting circuit 101, a drawing in light yellow is discriminated and converted to a visible image. A chrominance signal processing part 402 generates print colors [Yellow (Y), Magenta (M), Cyan (C) and Black (K)] from inputted color (R, G and B) signals. In the case of yellow printing, an equipment number is added to an image signal and since the Yellow is hardly identified to human eyes, however, it is used for specifying equipments. This yellow drawing is converted to the electric signal of the visible image, and an image developing this signal to a photosensitive drum 217 is transferred to a paper sheet.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention particularly relates to an image processing apparatus having a function of detecting a specific original.

0002

2. Description of the Related Art In recent years, as the image quality and color of copying machines have increased, there has been a risk of counterfeiting of specific documents such as banknotes and securities. Therefore, in order to prevent the copy from being misused, a technique is known in which a machine number is added to the copied image to identify the copying machine that made the copy. In particular, taking advantage of the fact that light yellow text drawn on a white background is difficult for the human eye to distinguish, a specific pattern image (hereinafter referred to as a "specific pattern") using light yellow line drawings is created.
A method of adding .

0003

[Problems to be Solved by the Invention] However, in the above conventional example, in order to visually see the specific pattern added to the document, it is necessary to look through a blue translucent film, for example, and the device number obtained from the pattern image is The disadvantage was that the recognition method was complicated.

The present invention has been made in view of the above-mentioned drawbacks of the conventional example, and its purpose is to perform image processing that can visually reproduce a specific pattern added to an original image on an output image. The point is to provide equipment.

[0005]

[Means for solving the problem] Solving the above problems,
In order to achieve the object, an image processing apparatus according to the present invention inputs an electrical signal corresponding to the original image into an image processing apparatus that processes an original image including a non-visualized image formed according to predetermined conditions. an input means, a detection means for detecting an electric signal corresponding to the non-visualized image according to the predetermined condition from an electric signal inputted by the input means, and an electric signal corresponding to the visualized image from the electric signal detected by the detection means; and conversion means for converting into.

[0006]

[Operation] According to this configuration, the input means inputs an electric signal corresponding to the original image, the detection means detects an electric signal corresponding to a non-visualized image according to predetermined conditions from the electric signal inputted by the input means, The converting means converts the electrical signal detected by the detecting means into an electrical signal corresponding to the visualized image.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

In the following embodiments, a copying machine is shown as an example of application of the present invention, but it is needless to say that the present invention is not limited to this and can be applied to various other apparatuses. Furthermore, in each device applicable to the present invention, specific documents such as banknotes and securities are targeted for counterfeit prevention.

<First Embodiment> First, the overall configuration of the copying apparatus will be explained.

FIG. 2 is a side sectional view showing the structure of a copying machine according to a first embodiment. In the figure, 201 is an image scanner section, which reads an original and performs digital signal processing. Further, 202 is a printer section, which prints out an image corresponding to the original image read by the image scanner section 201 on paper in full color.

In the image scanner section 201, 20
0 is a mirror pressure plate, and the platen glass (hereinafter referred to as "platen")
A document 204 on a 203 (hereinafter referred to as ``CCD'') is illuminated by a lamp 205, guided by mirrors 206, 207, and 208, and imaged by a lens 209 on a 3-line sensor (hereinafter referred to as CCD) 210, which displays full color information. (G
), which is sent to the signal processing unit 211 as a blue (B) component. Note that 205 and 206 are moved at a speed v, and 207 and 208 are moved mechanically at a speed of 1/2v in a direction perpendicular to the electrical scanning direction of the line sensor, thereby scanning the entire surface of the document. The signal processing unit 211 electrically processes the read signal and decomposes it into magenta (M), cyan (C), yellow (Y), and black (Bk) components, and sends them to the printer unit 202. Also, for each document scan (scanner) in the image scanner section 201, one component among M, C, Y, and Bk is sent to the printer section 202, and one printout is made by scanning the document four times in total. Complete.

M, C, Y or Bk image signals sent from the image scanner section 201 are sent to a laser driver 212. The laser driver 212 modulates and drives the semiconductor laser 213 according to the image signal. The laser beam is transmitted through a polygon mirror 214, an f-θ lens 215, and a mirror 2.
16, the photosensitive drum 217 is scanned.

Reference numeral 218 denotes a rotary developing device, which includes a magenta developing section 219, a cyan developing section 220, and a yellow developing section 221.
, a black developing section 222, and four developing devices alternately contact the photosensitive drum 217 to develop an electrostatic latent image formed on the photosensitive drum 217 with toner. Reference numeral 223 denotes a transfer drum, which winds the paper fed from the paper cassette 224 or 225 around the transfer drum 223, and transfers the image developed on the photosensitive drum 217 onto the paper.

After the four colors M, C, Y, and Bk have been sequentially transferred in this manner, the paper passes through the fixing unit 226 and is discharged.

FIG. 3 shows CCD(R) 301, CCD(G
) 302 and CCD (B) 303 according to the wavelength of light.

FIG. 4 is a block diagram illustrating the configuration of the image scanner section 201 shown in FIG. A main scanning address 102 specifying the address is output. That is, when the horizontal synchronization signal HSYNC is "1", the CP (not shown)
The pixel clock signal CLK is set to a predetermined value by U.
is incremented by .

The image formed on the three-line sensor 210 is photoelectrically converted by the three line sensors 301 and color 303, and is output as read signals of R, G, and B components to amplifiers 304 to 306 and a sampling and holding circuit. 307-309 and A/D converters 310-3
12, an 8-bit digital image signal 313 for each color (
(corresponding to R), a digital image signal 314 (corresponding to G), and a digital image signal 315 (corresponding to B).

<Signal Processing Block> FIG. 1 is a block diagram showing the configuration of the signal processing section (image processing unit) 211 shown in FIG. 2. Units that are the same as those in FIG. 1 are given the same reference numerals. In FIG. 1, CLK is a clock signal that transfers pixels. HSYNC is a horizontal synchronization signal, which is a synchronization signal for starting main scanning. Reference numeral 103 is a control unit, which includes a CPU for controlling the entire device, a ROM that stores operating programs, a RAM that has a work area for various programs, and CLK, HSYNC, and VSY.
Consists of a circuit that generates NC, especially the synchronizing signal CL.
It has the function of generating K, HSYNC, and VSYNC. Reference numeral 107 denotes an operation section, which includes keys and a display section for inputting instructions for copying operations of the present apparatus and various parameters related to copying. Inside the signal processing unit 211, a specific pattern image correction circuit 101 has a function of applying correction to the color signals R, G, and B from the image scanner unit 201 as described below. 402 is a color signal processing unit;
Color signals R, G, from the specific pattern image correction circuit 101
It has a function of generating a print signal from B. A pattern adding circuit 102 has a function of adding a specific pattern, which will be described later, to the print signal from the color signal processing unit 402. Reference numeral 108 denotes a CPU, which has a function of controlling the overall operation of the signal processing section 211 according to a program stored in a ROM (not shown), and also generating an apn signal and a CNO signal, which will be described later.

Here, the 2-bit CNO signal is a frame sequential signal, M (magenta), C (cyan), Y (yellow).
, Bk (black), and is a signal for indicating the print color currently being printed. FIG. 13 shows the relationship between the possible values of the CNO signal and print output.

The apn signal is a signal that specifies whether or not to convert a specific pattern into a visible image signal. In other words, it is a signal that is controlled on/off by the CPU 104 based on a designation from the operation unit 107. It is assumed that the initial state of the anp signal is on, and if there is no change, it is converted into a visible image signal.

The operation of the above configuration will be explained. Color image signals (R, G, B) read by the image scanner section 201 are input to the specific pattern image correction circuit 101. A specific pattern correction circuit 101 discriminates the light yellow line drawing and converts it into a visible image signal. In the color signal processing unit 402, input colors (R, G, B
) signals to generate print color signals (Y, M, C, K). A pattern adding circuit 102 adds the equipment number to the image signal during yellow printing. <Specific pattern image correction circuit 101> FIG. 5 is a block diagram showing the circuit configuration of the specific pattern image correction circuit 101 according to the first embodiment. In the figure, 501 is a line drawing determination unit that determines whether the pixel in question is a line drawing part. A color determining unit 502 determines whether the pixel in question is pale yellow. 1201, 1202, 1203 are selectors, and when the output from the AND circuit 1207 is 0, the input R
, G, and B signals, and when the output from the AND circuit 1207 is 1, the values of the registers 1204, 1205, and 1206 are selected. Registers 1204, 1205, and 1206 are 8-bit registers whose values are set by the CPU 104. Furthermore, registers 1204, 1205, 12
The value stored in register 06 may be a value given from another configuration, in which case registers 1204, 1205,
The configuration of 1206 can be omitted. In this embodiment, "0" is set and stored in all registers 1204, 1205, and 1206. Line buffers 1208 to 1211 have a function of delaying one line of image signals. 1
207 is an AND gate, which outputs the ap signal, the output of the line drawing stabilization unit 501, and the output of the color determination unit 502 (1 line delay)
It has a function to perform logical AND with.

Specific pattern image correction circuit 10 configured as described above
1, the AND gate 1207 determines from the input color signals R, G, and B that the pixel of interest has a light yellow color component and is a line drawing portion, and that the apn signal 109 is "
1” and outputs “1”, selectors 1204 to 1206 select registers 1204 to 1, respectively.
206 and set the output to pure black (R=0, G=0, B=
0). On the other hand, when the condition is such that the AND gate 1207 outputs "0", an operation is performed in which the input color signals R, G, and B are output without being corrected.

Next, the specific pattern image correction circuit 10
Each circuit configuration of No. 1 will be explained in detail. FIG. 6 is a block diagram showing the circuit configuration of the color determining section 502 according to the first embodiment. In the figure, 601 is a Lab conversion circuit that converts input R, G, and B signals into a luminance signal L and color component signals a and b.
This is a product-sum calculator for a 3×3 dot matrix. Comparison calculators 602 and 604 determine whether the luminance signal L is within a predetermined value range (C0<L<C1).

603 is a lookup memory (hereinafter referred to as "LU").
It is configured to output "1" when the color component signals a and b are in a specific value range, that is, the yellow component, and to output "0" otherwise. ing.

<Line drawing determining section 501> FIG. 7 is a block diagram showing the configuration of the line drawing determining section 501 according to the first embodiment. In the same figure, 705 and 706 are line buffers,
A delay of one line of pixels is performed. An edge amount calculation circuit 701 calculates an edge amount from a 3×3 pixel matrix centered on the pixel of interest. 704 is a register with a constant P
I remember. A comparator 702 compares the output OUT of the edge amount calculation circuit 701 with a constant P from the register 704, and sets the output to "1" when the relationship OUT>P.
The other values are set to "0". Note that the constant stored in the register 704 may be a value given from another configuration,
In this case, the configuration of register 704 can be omitted.

9 and 10 are block diagrams showing the configuration of the edge amount calculation circuit 701 according to this embodiment, and FIG. 8 is a diagram illustrating an edge calculation method by the edge amount calculation circuit 701 according to this embodiment. Further, FIG. 16 is a diagram illustrating an image pattern in which a large amount of edges is calculated in the first embodiment.

In FIGS. 9 and 10, 1901 to 19
09 is a latch circuit that delays one pixel each; 10
01 to 1004 are computing units that calculate the average of two inputs, and 1005 and 1006 are the larger of the two inputs (
1007 is an arithmetic unit that outputs the larger one (max) from two inputs, 1008 is an arithmetic unit that outputs the smaller one (min) from two inputs, and , 1009 is the difference between the two inputs from the arithmetic units 1007 and 1008, that is, (max)-(
This is an arithmetic unit that calculates min).

The operation of the above configuration will be explained.

Input signals E1, E2, E3 delayed by line buffers 705, 706 (FIG. 7) are delayed by nine latch circuits 1901-1909 to form a 3.times.3 window. Figure 8 shows this window state.
It is. On the other hand, the calculations shown in FIG. 8 are performed by the calculation units 1001 to 1009. As a result, an edge amount signal (OUT) is output.

Note that the value of OUT 703 calculated from a 3×3 pixel matrix centered on the pixel of interest becomes a particularly large value in the case of a pattern of four straight lines as shown in FIG. Therefore, since the specific originals that cannot be copied, such as banknotes, are mostly composed of line drawings and backgrounds, the above circuit configuration can effectively detect the shapes that exist in the originals, that is, the straight parts. . Further, in this embodiment, in order to detect yellow thin lines, a method is used in which a line drawing portion is extracted using a B signal that is sensitive to a yellow image. It should be noted here that the present invention is not limited to the case shown in FIG. 16 above, in which the value of the edge amount OUT becomes large.

<Pattern Addition Circuit> FIG. 11 is a block diagram showing the configuration of the pattern addition circuit 102 according to the first embodiment. In the figure, 901 is a sub-scanning counter;
02 is a main scanning counter, 903 is a lookup table (hereinafter referred to as "LUT"), 905 is a flip-flop, 906 is a register storing a predetermined value, 913
is an AND gate, 911 is an AND gate, and 912 is an adder. Note that the value stored in the register 906 may be a value given from another configuration, and in this case, the configuration of the register 906 can be omitted.

Here, the sub-scanning counter 901 repeatedly counts the main-scanning synchronizing signal HSYNC, and the main-scanning counter 902 repeatedly counts the pixel synchronizing signal CLK, each having a width of 9 bits, that is, 512 cycles. LUT903 input signal V
This is a read-only memory that holds a specific pattern to be added to the sub-scanning counter 901 and the lower six bits of the count value of the main-scanning counter 902, respectively. Only one bit of the output of the LUT 903 is referenced, and an AND gate 904 performs ANDing with the three bits each of the main scanning counter 901 and the sub-scanning counter 902, and a flip-flop 905 synchronizes with the CLK signal. The AND gate 913 outputs the inverted signal of the CNO signal “0” and the CNO signal “0”.
1” and then the AND gate 9
Sent to 11. In this way, the specific pattern from LUT 903 is valid only when CNO=2, that is, when yellow is currently being printed.

On the other hand, a value P1 is held in the register 906, and this P1 is a threshold value for determining the presence/absence of an edge based on the edge amount 703 calculated by the edge amount calculation circuit 701. After passing through an AND gate 911, an adder 912 adds a specific pattern to the input signal V and outputs V'. Therefore, when CNO=2, that is, when yellow is currently being printed, the specific pattern held in the LUT 903 is repeatedly read out and added to the signal to be output. Here, the specific pattern to be added is added using only yellow toner so that it is difficult for the human eye to discern, but this is because the human eye has a weak ability to discern patterns drawn with yellow toner. This is what was used. Note that the specific pattern image on the copy can be visually observed by looking through a blue translucent film, for example.

Note that when the color signals R, G, and B are corrected by the specific pattern image correction circuit 101, R=G=B=0.
The effect of the pattern addition circuit 102 becomes weak due to the black output due to the black output, but on the other hand, if no correction is made, the effect of making the specific pattern addition invisible by the pattern addition circuit 102 becomes noticeable.

<Description of Print Original> FIG. 12 is a diagram illustrating an output image according to the first embodiment. In the same figure, "03250" which is invisible in the read document 1201
90'' is added, a print image 1202 can be output by the process of this embodiment described above.The specific pattern, which was not visible in the read original, is converted into a print image 1202 so that it is visible. appear.

As explained above, according to the first embodiment, a specific pattern added on a document that is difficult for the human eye to discern is detected, and a visible image signal, that is, a specific pattern on the document is detected. The image signal is set to black (R=0, G=0, B=0
), the specific pattern added to the read document can be visually recognized in the output image.

(Second Embodiment) FIG. 14 is a block diagram showing the circuit configuration of a specific pattern image correction circuit according to a second embodiment. In the second embodiment, the same configuration as the first embodiment described above is used, so a description of the configuration will be omitted.

Furthermore, in the first embodiment, the image signal of a specific pattern on the original was converted to black (R=0, G=0, B=0), but in this embodiment, the register 1206
By setting 255 in the register 1206' corresponding to , and setting "0" in registers 1204 and 1205, the image signal of a specific pattern on the document is converted to red.

In this embodiment, registers 1204,
By changing the values set in 1205 and 1206', the color density of the specific pattern image visualized on the print document can be controlled.

(Third Embodiment) FIG. 15 is a block diagram showing the circuit configuration of a specific pattern image correction circuit according to a third embodiment. The third embodiment uses a configuration substantially similar to that of the first embodiment described above, so a description of the configuration except for different components will be omitted.

In the third embodiment, the specific pattern visualized on the printed image is easily found by performing signal conversion on images other than the specific pattern image on the read document.

That is, in this embodiment, in FIG. 15, OR circuits 1301, 1302, and 1303 are provided, and a
An OR operation is performed for each bit between the pn signal 109 and each of the R, G, and B signals, thereby making it possible to extract only a specific pattern on the read document and print it out.

[0043] In this way, it is possible to easily extract only a specific pattern from the document. Note that the present invention may be applied to a system made up of a plurality of devices, or to an apparatus made up of one device. It goes without saying that the present invention can also be applied to cases where the present invention is achieved by supplying a program to a system or device.

[0044]

[Effects of the Invention] As explained above, according to the present invention,
A specific pattern added to a read document can be visually reproduced in an output image.

[Brief explanation of drawings]

[Figure 1] Signal processing unit (image processing unit) shown in Figure 2
211 is a block diagram showing the configuration of the device 211.

FIG. 2 is a side sectional view showing the configuration of the copying machine of the first embodiment.

[Figure 3] CCD (R) 301, CCD (G) 302, C
It is a figure showing the relative sensitivity according to the wavelength of light of CD (B) 303.

4 is a block diagram illustrating the configuration of an image scanner section 201 shown in FIG. 2. FIG.

FIG. 5 is a block diagram showing the circuit configuration of a specific pattern image correction circuit 101 according to the first embodiment.

FIG. 6 is a block diagram showing a circuit configuration of a color determining section 502 according to the first embodiment.

FIG. 7 is a block diagram showing the configuration of a line drawing determining section 501 according to the first embodiment.

FIG. 8 is a diagram illustrating an edge calculation method by an edge amount calculation circuit 701 according to the present embodiment.

FIG. 9 is a block diagram showing the configuration of an edge amount calculation circuit 701 according to the present embodiment.

FIG. 10 is a block diagram showing the configuration of an edge amount calculation circuit 701 according to the present embodiment.

FIG. 11: Pattern addition circuit 102 according to the first embodiment.
FIG.

FIG. 12 is a diagram illustrating an output image according to the first example.

FIG. 13 is a diagram showing the relationship between possible values of the CNO signal and print output.

FIG. 14 is a block diagram showing the circuit configuration of a specific pattern image correction circuit according to a second embodiment.

FIG. 15 is a block diagram showing the circuit configuration of a specific pattern image correction circuit according to a third embodiment.

FIG. 16 is a diagram illustrating an image pattern in which a large amount of edges is calculated in the first embodiment.

[Description of symbols] 101 Specific pattern image correction circuit 102 Pattern addition circuit 103 Control section 107 Operation section 108 CPU 109 ANP signal 200 Mirror pressure plate 201 Image scanner section 202 Printer section 203 Platen 204 Original 205 Lamps 206, 207, 208 Mirror 209 Lens 210 3-line sensor 211 Signal processing section 212 Laser driver 213 Semiconductor laser 214 Polygon mirror 215 f-theta lens 216 Mirror 217 Photosensitive drum 218 Rotating developer 219 Magenta developing section 220 Cyan developing section 221 Yellow developing section 222 Black developing section 223 Transfer Drums 224, 225 Paper cassette 226 Fixing units 301 to 303 CCD 304 to 306 AMP 307 to 309 S/H 310 to 312 A/D 501 Line image determination section 502 Color determination section 601 Lab conversion circuit 602, 604, 702 Comparator 605, 606, 704, 1204-1206 Registers 607, 1207 AND gate 701 Edge amount calculation circuit 705, 706 Line buffer 1001-1009 Arithmetic unit 1208-1211 Line buffer 1201-12
03 Selector 1901-1909 Latch

Claims (2)

[Claims] 1. An image processing apparatus for processing a document image including a non-visualized image formed according to predetermined conditions, comprising: input means for inputting an electrical signal corresponding to the document image;
a detection means for detecting an electric signal corresponding to the non-visualized image according to the predetermined condition from an electric signal input by the input means; and a conversion for converting the electric signal detected by the detection means into an electric signal corresponding to the visualized image. An image processing device comprising: means. 2. The image processing apparatus according to claim 1, wherein the predetermined condition includes that the non-visualized image is a line drawing, and that the line drawing has a yellow color component.