JP2001069340A - Picture processor, its method and recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a device for easily detecting specific information without lowering the definition of a picture with respect to an output picture by constituting an information generating means to prepare specific information as a pixel pattern forming a two-dimensional array. SOLUTION: An information generating means prepares specific information as a pixel pattern forming a two-dimensional array. In this device, a pulse width modulator(PWM) 212 outputs the pulse signal of a pulse width corresponding to the level of a picture signal inputted from an LUT 211, and the pulse signal is inputted to a laser driver for driving a semiconductor laser in a laser exposing optical system. A pattern generator 217 holds specific information and outputs the specific information directly to the part 212 as needed to execute pattern adding processing. In this case, by making an additive pattern two-dimensional, featuring of a pattern is facilitated and by extracting the feature from an output picture, the reading precision of the additive pattern is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image processing apparatus and method, and a recording medium, for example, an image processing apparatus and method for adding specific information to image data, and a recording medium.

[0002]

2. Description of the Related Art As an image processing apparatus for performing digital signal processing on image data, an image processing apparatus having a function of preventing forgery of bills, securities, and the like has been widely used.

[0003] Forgery prevention functions include, for example, identifying bills and securities when reading an original image, forcibly stopping the operation of the apparatus based on the identification result, and specifying an output image to be visually recognized. By adding the information, forgery can be avoided.

[0004] Alternatively, by adding a specific signal to an output image to embed information that is not visually recognized, it has been easy to track a counterfeit at the time of forgery.

More specifically, of a plurality of output color components (for example, magenta, cyan, yellow, and black) in an image output device, an output color component (for example, yellow) which is least visible to human eyes is used. The image signal of the color component is modulated, for example, by adding a constant value, or an arbitrary signal is forcibly added to specify the number or code indicating the serial number of the image output device. Information was added. Alternatively, the addition of the specific information is repeated at regular intervals in the entire area of the output image.

[0006]

However, in the above-described conventional forgery prevention technology, even if the specific information is added to the color component which is most invisible, the deterioration of the image quality cannot be avoided. To do so had to be minimized.

For example, when it is desired to output a particularly detailed image, a pattern which does not exist in the original in the output image should not be visually recognized.

For example, when copying an original of a uniform color in a color image processing apparatus, the original is read C
The read image signal is not always uniform due to the sensitivity variation of the CD or the like. However, when printing out an image input via an external interface of the apparatus, a CG (computer graphics) image is directly output. Since it is possible to output, a uniform area can sufficiently exist at the image signal level. In the case of processing an image of a uniform color as described above, if modulation is performed on the yellow component, specific information for preventing forgery becomes more conspicuous particularly in a uniform color region of light gray or light blue.

Further, the unit patterns sewn numbers and codes indicating specific information in a small area, in the method for configuring the additional pattern by repeating the unit pattern at regular intervals, just because the unit pattern is held together small Because it is more noticeable and the human eye can recognize regular patterns more than random patterns,
When the unit patterns are arranged in a grid pattern, they become more noticeable. Therefore, the degree of modulation of the image signal must be reduced, and the additional pattern may not be read depending on the original.

Further, in recent years, image processing apparatuses for outputting a binary image which pseudo-displays a multi-valued image by pseudo halftone have become widespread, and it is necessary that such an image processing apparatus be similarly provided with a forgery prevention function. Has arisen. However, an image (pixel) is "formed" / "not formed" for binary output
Only the two cases can be selected, and the additional pattern becomes conspicuous. Therefore, the additional pattern must be small or small, and the additional pattern may not be read depending on the original.

Therefore, there is a need for a modulation method or an additional pattern that satisfies the condition of being invisible in all output images and having the opposite direction of being traceable by some method.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem, and has been made in consideration of the above-described circumstances. It is an object to provide an apparatus, a method thereof, and a recording medium.

[0013]

As one means for achieving the above object, the image processing apparatus of the present invention has the following arrangement.

That is, image input means for inputting image data, information generating means for generating specific information, information adding means for adding the specific information to the image data, and an image to which the specific information has been added. Image forming means for forming an image based on data, the information generating means,
The specific information is generated as a pixel pattern forming a two-dimensional array.

For example, the pixel pattern is characterized in that its constituent pixels are not adjacent to each other in the horizontal and vertical directions.

For example, the pixel pattern is characterized by being constituted by a plurality of pixels having different levels.

For example, the pixel pattern is constituted by a plurality of pixels having different sizes.

For example, the information adding means adds an inverted pattern of the pixel pattern.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment according to the present invention will be described below in detail with reference to the drawings.

First Embodiment [Apparatus Configuration] First, an overall configuration of an electrophotographic digital copying machine according to the present embodiment will be described.

FIG. 1 is a sectional view showing a schematic configuration of a digital copying machine. The digital copying machine shown in FIG. 1 includes a reader unit for reading an original image and generating an image signal, and an electrophotographic system in accordance with an image signal sent from the reader unit or an image signal input from an external device. And a printer unit for forming an image on a recording material. The operations of the reader unit and the printer unit described below are controlled by the respective controllers 100 and 200. As shown in FIG. 2 described later, the controller 200 includes a CPU 214, and performs control according to a program stored in a ROM in advance. Further, it goes without saying that the controller 100 also includes a CPU (not shown) and performs control according to a program stored in advance in a ROM (not shown).

Copy key (not shown) in reader unit
Is pressed, the original 30 placed on the original platen glass 31 is irradiated with light output from the exposure lamp 32a,
The reflected light from the document 30 is guided by a plurality of mirrors 32b and lenses 33 and forms an image on a full-color sensor 34 composed of a three-line CCD.

The full color sensor 34 includes a red (R),
CCD line sensors of three colors of green (G) and blue (B) are arranged at a predetermined distance from each other in the sub-scanning direction, and a plurality of light receiving elements are arranged in a line in each line sensor. The full-color sensor 34 separates the incident reflected light image from the document 30 into a plurality of pixels by a plurality of photoelectric conversion elements, and generates a photoelectric conversion signal (color-separated image signal) according to the density of each pixel.

The R generated by the full color sensor 34
The GB image signal is sent to the printer unit,
0, after image processing such as PWM described later is performed,
An image signal composed of each color component of magenta (M), cyan (C), yellow (Y), and black (K) is input to a polygon scanner 3 which is a laser exposure optical system. The polygon scanner 3 includes a semiconductor laser and a laser driver, and the semiconductor laser is driven according to an input image signal. The laser light E emitted from the semiconductor laser is swept by the rotating polygon mirror 3a of the polygon scanner 3,
A spot image is formed on the photosensitive drum 1 by the f-θ lens 3b and the fixed mirror 3c for directing the laser beam E toward the photosensitive drum 1. Thus, the laser beam E scans the photosensitive drum 1 in a direction substantially parallel to the rotation axis of the photosensitive drum 1 (main scanning direction), and repeatedly scans the photosensitive drum 1 in the rotation direction of the photosensitive drum 1 (sub-scanning direction). Thus, an electrostatic latent image is formed.

The photosensitive drum 1, which is an image carrier, has amorphous silicon, selenium, OPC and the like on its surface, and is rotatably carried in the direction of the arrow in the figure. Around the photosensitive drum 1, a pre-exposure lamp 11, a primary charger 2 such as a corona charger, a surface potential sensor 12, and developing units 4y and 4 for four colors.
c, 4m, 4k, light amount sensor 13, transfer unit 5, and
The cleaner 6 is arranged.

At the time of image formation, the photosensitive drum 1 is rotated in the direction of the arrow by the controller 200 so that the pre-exposure lamp 11
, And is uniformly charged by the primary charger 2. Thereafter, the photosensitive drum 1 is exposed and scanned with the laser beam E modulated in accordance with the above-described image signal, so that an electrostatic latent image having an area gradation characteristic is formed on the photosensitive drum 1 in accordance with the image signal. Formed.

The developing units 4y, 4c, 4m, and 4k develop the electrostatic latent image on the photosensitive drum 1 using yellow, cyan, magenta, and black color toners, respectively. Specifically, the photosensitive drum 1 is controlled by the controller 200.
The electrostatic latent image formed on the upper surface is transferred to predetermined developing units 4y, 4c,
By performing reversal development with a two-component developer composed of a toner and a carrier using 4m and 4k, a negatively charged visible image (toner image) based on a resin is formed on the photosensitive drum 1. These toners are formed by using a styrene-based polymer resin as a binder and dispersing color materials of each color. Here, the reversal development is a development method in which a toner charged to the same polarity as the latent image is adhered to an exposed area on the photoreceptor to visualize the toner. Incidentally, each developing device is selectively operated by an eccentric cam (not shown) according to each separation color.
Has a structure close to.

In the present embodiment, the transfer section 5 is opposed to a transfer drum 5a as a recording material carrier, a transfer brush charger 5b as a transfer means, and a suction brush charger 5c for electrostatically attracting the recording material. It includes a suction roller 5g, an inner charger 5d, an outer charger 5e, and a transfer peeling sensor 5h. A recording material carrying sheet 5f made of a dielectric material such as polycarbonate is integrally stretched in a cylindrical shape in a peripheral opening area of the transfer drum 5a which is rotatably supported.

The controller 200 controls the recording material cassette 7
The recording material is supplied to the position facing the photosensitive drum 1 via the conveyance system and the transfer device 5 at a predetermined timing, and is carried on the recording material holding sheet 5f by electrostatic force. Then, the toner image formed on the photosensitive drum 1 is transferred to the recording material on the recording material holding sheet 5f according to the rotation of the transfer drum 5a.

When the transfer of the desired number of color toner images onto the recording material is completed, the controller 200 sets the separation claw 8
The recording material is separated from the transfer drum 5a by operating the separation push-up roller 8b and the separation charger 5i, and is discharged to the tray 10 via the heat roller fixing device 9.
Thereby, a full-color image is formed on the recording material.

After the transfer of the toner image, the controller 200 cleans the residual toner on the surface of the photosensitive drum 1 with a cleaner 6 including a cleaning blade and a squeeze sheet.
Prepare for the next image forming step.

The recording material supporting sheet 5 of the transfer drum 5a
In order to prevent scattering of powder on f and adhesion of oil on the recording material, etc., cleaning is performed using the backup brush 15 facing the fur brush 14 via the fur brush 14 and the recording material supporting sheet 5f. Do. Such cleaning is performed before or after image formation, and is performed as needed when a jam (paper jam) occurs.

Reference numeral 40 denotes an operation unit for inputting an instruction by a user, notifying the user of the state of the apparatus, and the like.

[Image Processing Block] FIG. 2 shows a functional block configuration of the controller 200 in the printer unit.
This will be described below.

The RGB image signal output from the full-color sensor 34 of the reader unit is converted into an analog signal processing unit 201.
After being input to and adjusting gain and offset,
The A / D converter 202 converts each color component into an RGB digital signal of, for example, 8 bits (0 to 255 levels: 256 gradations).

The RGB digital signal input to the shading correction unit 203 is optimized in gain corresponding to each light receiving element in order to eliminate the sensitivity variation of the individual light receiving elements arranged in a line in the full color sensor 34. General shading correction is performed.

The line delay unit 204 corrects a spatial shift included in the image signal output from the shading correction unit 203. This spatial shift is caused by the line sensors of the full-color sensor 34 being arranged at a predetermined distance from each other in the sub-scanning direction. Specifically, based on the B color component signal, the R and G color component signals are line-delayed in the sub-scanning direction, and the phases of the three types of color system signals are synchronized.

The input masking unit 205 converts the color space of the image signal output from the line delay unit 204 into, for example, an NTSC-RGB standard color space by a well-known matrix operation. That is, the color space of each color component signal output from the full-color sensor 34 is determined by the spectral characteristics of the filter of each color component.
To the standard color space.

Note that, from the external input interface 213, color image data displayed on, for example, a CRT display is input from an external device (not shown) such as a computer as necessary.

The LOG conversion unit 206 is constituted by a look-up table (LUT) composed of, for example, a ROM or the like, and converts the RGB luminance signal output from the input masking unit 205 into a CMY density signal.

The line delay memory 207 is output from the LOG converter 206 for a period (line delay period) during which the black character determination unit (not shown) generates the control signals UCR, FILTER, SEN, etc. from the output of the input masking unit 205. Delayed image signal. The control signal UCR is a control signal for controlling the masking / UCR unit 208, and the control signal FILTER is a control signal used by the output filter 210 to perform edge enhancement. The control signal SEN is a control signal used to increase the resolution when a black character is determined by a black character determination unit (not shown).

The masking / UCR unit 208 extracts a black component signal K from the image signal output from the line delay memory 207. Further, in order to correct the color turbidity of the recording color material in the printer unit, a matrix operation is performed on the MCYK image signal, and M, C,
For example, an 8-bit plane-sequential color component image signal is output in the order of Y and K. Note that the matrix coefficient used for the matrix calculation is set by the CPU 214.

The γ correction unit 209 controls the masking and U to adjust the image signal to the ideal gradation characteristics of the printer unit.
The CMYK image signal output from the CR unit 208 is subjected to density correction. Output filter (spatial filter processing unit) 210
Γ correction unit 2 according to a control signal from CPU 214
09 is subjected to edge enhancement or smoothing processing.

The LUT 211 is for matching the density of the original image with the density of the output image.
And so on. The conversion table is stored in the CPU 21
4 is set.

The pulse width modulator (PWM) 212 has an LU
A pulse signal having a pulse width corresponding to the level of the image signal input from T211 is output, and the pulse signal is input to the laser driver 41 for driving the semiconductor laser in the laser exposure optical system 3 as described above.

Reference numeral 217 denotes a pattern generator which holds specific information in the present embodiment, and performs PW
By directly outputting the information to the M unit 212, a pattern adding process described later is performed. Note that the process of actually adding the pattern generated by the pattern generator 217 to the image data is not limited to the PWM unit 212, and any configuration may be used as long as the pattern is added to the final formed image. It may be executed.

In the present embodiment, the functions shown in FIG. 2 are realized in the controller 200 of the printer unit. However, these functions may be realized in the controller 100 of the reader unit. That is,
RG read by the full color sensor 34 in the reader unit
B image signal can be converted into CMY images
It is sufficient if the signal can be appropriately converted into a K signal and supplied to the laser driver 41.

When the copying machine having the above-described configuration is provided with a forgery prevention function, specific information such as the serial number of the image processing apparatus is forcibly added at regular intervals to the image signal read by the reader unit. And output from a printer unit.

[Additional Pattern] An example of a general signal (additional pattern) indicating specific information is shown in FIG. FIG. 3 schematically shows 5 × 5 pixels around the target pixel. First, when the pattern 301 is added, although it is difficult to visually recognize the pattern 301 in the output image, it is difficult to read and track the pattern. To ensure that the additional pattern can be read, the patterns 302, 3
Number of pixels (signal amount) indicating the pattern as in 03 and 304
Or the addition period of the pattern in the output image is narrowed. However, the patterns 302, 303, and 304 are more easily recognized than the pattern 301. .

Therefore, in this embodiment, as shown in FIG. 3, the reading accuracy of the additional pattern is improved without using a method of increasing the signal amount of the pattern in one-dimensional direction or narrowing the period of the additional interval of the pattern. It is characterized by making it.

FIG. 4 shows examples (401 to 404) of additional patterns in the present embodiment. The pattern is generated by the pattern generator 217. In other words, it can be seen from the figure that a two-dimensional pattern is used as the additional pattern. By making the additional pattern two-dimensional in this way, it is easy to characterize the pattern, and by extracting the characteristic from the output image, it is possible to increase the reading accuracy of the additional pattern without narrowing the pattern addition interval cycle. Can be. In addition, instead of connecting all the pixels in the two-dimensional additional pattern, as shown in FIG. 4, the number of connected pixels is reduced by, for example, preventing the pixels constituting the pattern from being adjacent to each other in the horizontal and vertical directions. In this way, the additional pattern can be made inconspicuous in the output image.

<Modification 1> In order to make the additional pattern less noticeable, for example, if the output image is a multivalued image, the signal level of each pixel constituting the pattern has a characteristic as shown in FIG. Making it effective is also effective.

According to FIG. 5, that is, the signal level of the pixel constituting the pattern is uniformly changed as in a pattern 504, or signal values of different levels are combined as in patterns 502 and 503.

As a result, the additional pattern is further characterized, so that the reading accuracy of the additional pattern is further improved. Therefore, it is possible to easily automate the reading process of the additional pattern.

<Modification 2> To make the additional pattern less noticeable, if the size of the output pixel is variable, such as the dot diameter, the size of each pixel forming the pattern as shown in FIG. It is also effective to give the features to

According to FIG. 6, the size of the pixels constituting the pattern is uniformly changed as in the pattern 604, or pixels having different sizes are combined as in the patterns 602 and 603.

As a result, the additional pattern is further characterized, so that the reading accuracy of the additional pattern is further improved. Therefore, it is possible to easily automate the reading process of the additional pattern.

As shown in FIG. 7, it is of course possible to change both the signal level and the size of each pixel constituting the additional pattern and further characterize the pattern by the combination.

<Modification 3> In order to make the additional pattern more inconspicuous, it is effective to invert the pattern as shown in FIG. 8 in a high density region where the image density is equal to or higher than a predetermined value.

According to FIG. 8, that is, the signal levels of the pixels constituting the pattern are uniformly inverted as in the pattern 801.
Further, as in the case of the patterns 802 and 803, further characterization is performed by incorporating pixel values whose signal levels and sizes are changed.

As a method of adding the inverted pattern, the additional pattern for the low density region generated by the pattern generator 217 may be inverted after being controlled by the controller 200, or may be added. Based on the control, the pattern generator 217
However, an inverted pattern may be directly generated.

As described above, according to the present embodiment,
Deteriorating the quality of the output image to which the pattern is added, by forming the additional pattern in a two-dimensional array and further characterization by changing the level and size of the signal of each pixel constituting the pattern and combining them. In addition, the reading accuracy of the additional pattern can be improved.

In this embodiment, an example in which specific information is added as an additional pattern in an image processing apparatus having a reader unit has been described. However, the present invention is not limited to such a configuration, and the present invention is not provided with a reader unit. The same can be applied to the apparatus. For example, in a system in which a personal computer and a printer are connected, the processing of this embodiment may be realized in hardware in the printer, or may be realized in software in driver software in the personal computer. It is.

Although an example in which image formation in the printer unit is performed by an electrophotographic method has been described, the present invention is naturally applicable to an ink jet printer, a silver halide photographic printer, and the like. In particular, in an ink jet printer, it is possible to selectively use the density of ink and control the diameter of ink droplets, so that the present invention can be realized particularly easily.

[0065]

[Other Embodiments] Even if the present invention is applied to a system including a plurality of devices (for example, a host computer, an interface device, a reader, a printer, etc.), an apparatus (for example, a copying machine) Machine, facsimile machine, etc.).

Further, an object of the present invention is to supply a storage medium storing a program code of software for realizing the functions of the above-described embodiments to a system or an apparatus, and to provide a computer (or CPU) of the system or the apparatus.
And MPU) read and execute the program code stored in the storage medium.

In this case, the program code itself read from the storage medium realizes the functions of the above-described embodiment, and the storage medium storing the program code constitutes the present invention.

As a storage medium for supplying the program code, for example, a floppy disk, hard disk, optical disk, magneto-optical disk, CD-ROM, CD
-R, a magnetic tape, a nonvolatile memory card, a ROM, or the like can be used.

When the computer executes the readout program code, not only the functions of the above-described embodiment are realized, but also the OS (Operating System) running on the computer based on the instruction of the program code. ) May perform some or all of the actual processing, and the processing may realize the functions of the above-described embodiments.

Further, after the program code read from the storage medium is written into a memory provided in a function expansion board inserted into the computer or a function expansion unit connected to the computer, based on the instruction of the program code, It goes without saying that the CPU included in the function expansion board or the function expansion unit performs part or all of the actual processing, and the processing realizes the functions of the above-described embodiments.

[0071]

As described above, according to the present invention, specific information can be added to an output image without deteriorating the image quality, and the specific information can be easily detected.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a digital copying machine according to an embodiment of the present invention;

FIG. 2 is a block diagram showing a functional configuration of a controller 200.

FIG. 3 is a diagram showing an example of a general additional pattern;

FIG. 4 is a diagram showing an example of an additional pattern according to the embodiment;

FIG. 5 is a diagram showing an example of an additional pattern according to the embodiment;

FIG. 6 is a diagram showing an example of an additional pattern according to the embodiment;

FIG. 7 is a diagram showing an example of an additional pattern according to the embodiment;

FIG. 8 is a diagram showing an example of an additional pattern according to the embodiment;
It is.

[Explanation of symbols]

 34 Full color sensor 201 Analog signal processing section 202 A / D conversion section 203 Shading correction section 204 Line delay section 205 Input masking section 206 LOG conversion section 207 Line delay memory 208 Masking / UCR section 209 γ correction section 210 Output filter 211 LUT 212 PWM Unit 213 External input I / F 214 CPU 215 ROM 216 RAM 217 Pattern generator 41 Laser driver

Claims (11)

[Claims] An image input unit for inputting image data; an information generating unit for generating specific information; an information adding unit for adding the specific information to the image data; and an image to which the specific information is added. An image processing apparatus, comprising: an image forming unit that forms an image based on data; wherein the information generating unit generates the specific information as a two-dimensional array of pixel patterns. 2. The image processing apparatus according to claim 1, wherein constituent pixels of the pixel pattern are not adjacent to each other in the horizontal and vertical directions. 3. The image processing apparatus according to claim 1, wherein the pixel pattern includes a plurality of pixels having different levels. 4. The image processing apparatus according to claim 1, wherein the pixel pattern includes a plurality of pixels having different sizes. 5. The image processing apparatus according to claim 1, wherein the information adding unit adds an inverted pattern of the pixel pattern. 6. The image processing apparatus according to claim 5, wherein the information adding unit adds the reverse pattern in a high density area of the image data. 7. The image processing apparatus according to claim 5, wherein the information generating unit generates the reverse pattern. 8. The image processing apparatus according to claim 1, wherein the specific information is information for specifying the image processing apparatus. 9. An image processing apparatus according to claim 1, wherein said image forming means forms an image on a recording medium. 10. An image inputting step of inputting image data, an information generating step of generating specific information, an information adding step of adding the specific information to the image data, and an image to which the specific information is added An image forming step of forming an image based on data, wherein in the information generating step, the specific information is generated as a two-dimensional array of pixel patterns. 11. A recording medium on which a program code for image processing is recorded, wherein the program code includes at least a code for an image inputting step of inputting image data, a code for an information generating step for generating specific information, A code of an information adding step of adding the specific information to the image data; and a code of an image forming step of forming an image based on the image data to which the specific information is added, the information generating step , Wherein said specific information is generated as a two-dimensional array of pixel patterns.