JP3604880B2 - Image processing apparatus and method, and storage medium - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an image processing apparatus and method capable of adding additional information to an input image, and a storage medium storing the method.
[0002]
[Prior art]
2. Description of the Related Art In recent years, image recording apparatuses such as color printers and color copiers have been able to form high-quality images by improving performance. Under such circumstances, it is becoming possible to form images similar to securities such as banknotes, and techniques for suppressing such actions are known.
[0003]
For example, an addition method is known in which a dot pattern indicating a machine number of the image processing apparatus is added together with a printed color image so as to be hardly discernible to human eyes.
[0004]
Usually, this dot pattern has a predetermined size, and a plurality of dots are arranged within the predetermined size. The additional information can be expressed by the arrangement of the plurality of dots. This dot pattern is periodically printed on the entire screen. When a dot pattern is added to a color image composed of yellow, magenta, cyan, and black planes to make it difficult for human eyes to recognize, the dot pattern is added only to the yellow plane.
[0005]
By performing the above-mentioned addition, when an image for which image formation is supposed to be prohibited or a copy image for which copying is supposed to be prohibited appears, additional information (machine number) is decoded from these images. It is possible to specify the device that has formed the image.
[0006]
Conventionally, in one device (model) manufactured by each manufacturer, the amount of information embedded in the dot pattern has a fixed length.
[0007]
[Problems to be solved by the invention]
However, the additional information to be added to the image differs depending on the manufacturer of the device, and the amount of the additional information may be different. Further, it is necessary to set the density of the dots present in the dot pattern and the size of the dot pattern according to the characteristics of the device manufactured by each manufacturer.
[0008]
As described above, when the method of adding a dot pattern is different for each manufacturer or each device model, an image in which image formation should be prohibited or a copy image in which copying should be prohibited is decoded. On the side, decoding methods must be prepared for the number of manufacturers and the number of device models, and there is a problem that a large load is imposed.
[0009]
However, conventionally, there has been no method of adding a dot pattern that can correspond to these multiple manufacturers and models.
[0010]
The present invention has been made in view of the above conventional example, and in a technique of adding additional information as a dot pattern to an input image, a technique of adding different dot patterns to an image by a plurality of manufacturers or a plurality of types of devices. Even in such a case, an object of the present invention is to provide a technique that can easily decode the shape of each of these dot patterns.
[0011]
[Means for Solving the Problems]
In order to solve the above problems, according to the image processing apparatus of the present invention,
A dot pattern that represents predetermined additional information for an input image and is composed of a plurality of dots For each unit area Along with adding it to the human eye, In the unit area An adding unit that adds a reference pattern that specifies each dot arrangement point where there is a possibility that a plurality of dots may be present to the human eye so as to be difficult to identify, and an output that outputs an image to which predetermined additional information is added by the adding unit It is characterized by having means.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
In this embodiment, an image recording apparatus using color electrophotographic technology is described. However, the present invention is not limited to this, and can be applied to an image processing apparatus using a technique such as an ink jet method or a thermal transfer method.
[0013]
In the present embodiment, input image data is 8-bit multi-valued image data of each of M (magenta), C (cyan), Y (yellow), and BK (black). It is assumed that the input is performed in a frame-sequential manner.
[0014]
The image recording apparatus (laser beam printer) according to the present embodiment has a resolution of 600 dpi, and a dot pattern indicating additional information for forgery tracking is added only to the Y plane. By doing so, it becomes possible to make it difficult for human eyes to recognize as much as possible, and even if a color image to which additional information is added is used in the same manner as the original color image before adding the additional information. Becomes possible. The present invention is not limited to the case where additional information for tracking forgery is added. That is, the case where the name of the creator who created the original image, the name of the work of the image, or the like is used as the additional information is also included in the present invention.
[0015]
FIG. 1 shows a configuration of an image processing apparatus used in the following embodiments.
[0016]
Reference numeral 1000 denotes an image processing unit which sequentially inputs multi-valued image data composed of R, G, and B from an external device or another device inside the apparatus, and converts this image into multi-valued image data composed of M, C, Y, and K After the additional information described below is added only to the Y component of the multi-valued image data, the multi-valued image data of each color is converted into binary image data by PWM processing, and then the laser light emitting unit 1001 Output to The laser light emitting unit 1001 emits a laser beam L to be described later based on the input binary image data.
[0017]
The photoconductor drum 100 is uniformly charged to a predetermined polarity by the charger 101, and a first latent image of, for example, magenta is formed on the photoconductor drum 100 by exposure with the laser beam L. Next, in this case, a required developing bias voltage is applied only to the magenta developing device Dm to develop a magenta latent image, and a first magenta toner image is formed on the photosensitive drum 100.
[0018]
On the other hand, immediately before the transfer paper P is fed at a predetermined timing and the leading end thereof reaches the transfer start position, a transfer bias voltage (+1.8 KV) of the opposite polarity (for example, plus polarity) to the toner is applied to the transfer drum 102. Then, the first toner image on the photosensitive drum 100 is transferred onto the transfer paper P, and the transfer paper P is electrostatically attracted to the surface of the transfer drum 102. Thereafter, the magenta toner remaining on the photosensitive drum 100 is removed by the cleaner 103, and the photosensitive drum 100 is prepared for a latent image forming and developing process of the next color.
[0019]
Next, as in the case of magenta, a second latent image of cyan is formed on the photosensitive drum 100 by the laser beam L, and then the second latent image on the photosensitive drum 100 is formed by the developing unit Dc for cyan. Is developed to form a second cyan toner image.
[0020]
Then, the cyan second toner image is transferred to the transfer paper P in accordance with the position of the magenta first toner image previously transferred to the transfer paper P. In the transfer of the second color toner image, a bias voltage of +2.1 KV is applied to the transfer drum 102 immediately before the transfer paper reaches the transfer portion.
[0021]
Similarly, the third and fourth latent images of yellow and black are sequentially formed on the photosensitive drum 100, and the respective latent images are sequentially developed by the developing units Dy and Db, respectively, and the toners previously transferred to the transfer paper P are respectively. The third and fourth toner images of yellow and black are sequentially transferred in alignment with the image, and a full-color image in which four toner images are superimposed on the transfer paper P is formed.
[0022]
Next, additional information added by the image processing apparatus according to the present embodiment will be described.
[0023]
FIG. 2 shows a state in which additional information is added to the image represented by the image data input to the image processing apparatus in the present embodiment. As described above, in the present embodiment, the additional information is such that the additional information (dot pattern) is added only to the Y plane. Therefore, FIG. 2 shows the color composed of the Y, M, C, and K planes. The image shown by the Y plane of the image is shown.
[0024]
In the figure, a shaded area 201 is a unit area for indicating additional information added to this color image (yellow plane) in the present embodiment. That is, one dot pattern is added in this unit area. The unit area 201 periodically exists in the color image (yellow plane) as shown in the figure. By doing so, it is possible to analyze the additional information with respect to any area of the color image finally formed after the additional information is added. Hereinafter, this unit area 201 is referred to as an inspection block.
[0025]
The three dots indicated by 202 are called fiducial marks, and indicate the starting position of each inspection block 201 and the directions of main scanning and sub-scanning. Further, the reference mark 202 has some information, which will be described later in detail.
[0026]
Also, a plurality of small-area dots composed of a plurality of pixels described later are arranged in each inspection block 201, and additional information can be represented by the arrangement method of each dot. Hereinafter, this dot is called an inspection dot.
[0027]
FIG. 3 is a diagram showing the inspection block 201 of FIG. 2 in detail.
[0028]
In the inspection block 201, guidelines 301 and 302 exist vertically and horizontally. A line 301 in the vertical direction (sub-scanning direction) is a sub-scanning line, and a line 302 in the horizontal direction (main scanning direction) is a main-scanning line. Call. In the present embodiment, there are 0, 1,...
[0029]
The circles shown at 303 indicate points where inspection dots may be arranged. In the present embodiment, these points are the intersections of odd-numbered main scanning lines and even-numbered sub-scanning lines, and even-numbered At the intersection of the main scanning line and the odd-numbered sub-scanning line.
[0030]
Hereinafter, each point where the inspection dots may be arranged is referred to as 303, and is referred to as a dot arrangement point. The additional information added to the image (yellow plane) can be expressed by whether or not a test dot is added to each dot arrangement point 303. Each dot arrangement point 303 is configured to be separated from each other by a distance 21 in the main scanning direction and the sub-scanning direction.
[0031]
In the figure, the reference mark 202 is composed of three dots, and two dots extending in the main scanning direction and two dots extending in the sub-scanning direction so that the interval (2l) between the dot arrangement points 303 can be defined. Are separated from each other by a distance l. Thus, no matter what the distance 2l between the adjacent dot arrangement points 303 is, the value can be calculated from the reference mark distance l when decoding the additional information (dot pattern). In the present embodiment, the distance between the main scanning lines and the distance between the sub-scanning lines are the same. For example, the distance between the main scanning lines 0 to 11 is l, and the distance between the sub-scanning lines 0 to 11 is 1. It is possible to cope with the case where each distance is l '. In this case, the distance between two dots extending in the sub-scanning direction of the reference mark 202 may be changed to l'.
[0032]
In the present embodiment, the three dots forming the reference mark 202 and the shape of each inspection dot are the same.
[0033]
Further, in the present embodiment, the size of each inspection block 201 can be indicated based on the distance L between the reference mark 202 corresponding to a certain inspection block 201 and the reference mark 202 corresponding to the adjacent inspection block 201. That is, in the present embodiment, the size of the inspection block 201 in the main scanning direction and the sub-scanning direction is L-2 × 1.
[0034]
As described above, as long as the reference mark 202 can be decoded, the shape of the inspection block 201 can be calculated.
[0035]
Therefore, the number n of main scanning and sub-scanning lines in the inspection block is:
n = (L−2 × l) / l + 1
Can be calculated as
[0036]
The values of L, l, and n can be freely set for each manufacturer that manufactures each device and for each model of each device, and can be adjusted according to the size of the inspection block 201, the dot density, and the amount of information to be embedded. It is possible to make optimal settings. Therefore, at the time of decoding, by detecting the reference mark 202 and measuring the distances L and l, the positions of the main scanning and sub-scanning lines and the positions of the dot arrangement points can be specified, and the additional information is decoded. It is possible to do.
[0037]
In the present embodiment, the positional relationship between the three dots of the reference mark 202 is controlled so as not to appear between the test blocks. Thus, when a plurality of dots as shown in FIG. 3 are decoded from the yellow plane, the reference mark 202 can be determined relatively easily from the dot arrangement status.
[0038]
Next, information represented by each dot arrangement point 303 will be described.
[0039]
In FIG. 3, an area 304 is an area for representing a maker ID (manufacturer name), and areas of main scanning lines 0 to 7 and sub-scanning lines 0 to 4 are always assigned to represent this information.
[0040]
An area 305 is an area for representing a model name (printer type).
[0041]
The other area is an area for representing a machine number unique to each printer or some information related to an image to be added.
[0042]
In the above three areas, a part is a point for indicating each of the above information, and another part is a point for adding a parity bit.
[0043]
In the present embodiment, the number of main scanning and sub-scanning lines in which the dot arrangement point 303 exists is both 12 lines. However, as described above, the number of lines can be determined based on the reference mark 202. It can be set freely for each model.
[0044]
Next, a procedure for decoding the additional information added to the image based on the image formed by the image processing apparatus will be described with reference to FIG. 4, and a method for expressing the additional information will be described.
[0045]
First, the inspection dots are read by, for example, reading a color image to which additional information has been added by a scanner, extracting only the image of the Y (yellow) plane to a host computer, and reading each position of the inspection dots on a monitor of the host computer. Do it by checking.
[0046]
First, the above-described reference mark 202 is detected. In FIG. 4, since the positional relationship between the three dots forming the reference mark 202 does not exist in the inspection block, the reference mark 202 can be easily determined.
[0047]
Next, the main scanning and sub-scanning directions of the inspection block are specified based on the positional relationship between the three dots forming the reference mark 202.
[0048]
Further, the distance l between the main scanning lines and the distance l between the sub-scanning lines where the dot arrangement points 303 exist are measured based on the positional relationship between the three dots.
[0049]
The size (L−2 × l) of the inspection block 201 is determined by measuring the distance L based on the positional relationship between the next reference mark 202 and the reference mark 202 adjacent in the main scanning direction and the sub scanning direction. I do.
[0050]
Next, based on the relationship n = (L−2 × l) / l + 1, the position of the dot arrangement point in the main scanning direction and sub-scanning direction inspection block 201 is specified.
[0051]
Next, corresponding additional information is determined based on the presence or absence of a dot at this dot arrangement point.
[0052]
Hereinafter, the dot arrangement points 303 on the main scanning line n are sequentially referred to as a _n0 , A _n1 , ..., a _n5 It is assumed that the case where test dots are arranged is 1 and the case where test dots are not arranged is 0.
[0053]
First, a method of analyzing the area 304 representing the manufacturer ID will be described. Note that the dot arrangement points existing in the area 304 are a ₀₀ , A ₀₁ , A ₀₂ , A ₀₃ , ~ A ₄₀ , A ₄₁ , A ₄₂ , A ₄₃ , Which is a total of 20 dot arrangement points.
[0054]
In the present embodiment, a dot arrangement point a on the main scanning line 0 in the area 304 ₀₀ , A ₀₁ , A ₀₂ , A ₀₃ Is controlled so that only one point becomes 1 (dots exist) and the other three points become 0 (no dots exist). That is, the above four points represent 2-bit information.
[0055]
The same control is performed on the dot arrangement points on the main scanning lines 1, 2, and 3 in the area 304, and 8-bit information can be represented by 16 dot arrangement points in the area 304.
[0056]
Note that a which exists on the main scanning line 4 ₄₀ , A ₄₁ , A ₄₂ , A ₄₃ Is a point for parity check.
[0057]
FIG. 5 is a diagram for explaining a method of parity check on information (manufacturer ID) in the area 304. a ₀₀ ~ A ₄₃ Are arranged as shown in the figure. ₄₀ , A ₄₁ , A ₄₂ , A ₄₃ Is an even parity in the direction of the arrow in the figure. If an error occurs in the parity check, the inspection dot is read again.
[0058]
On the other hand, if no error occurs in the parity check, a ₀₀ , A ₀₁ , A ₀₂ , A ₀₃ Is converted to the following 2-bit value according to the value of
[0059]
(A ₀₀ a ₀₁ a ₀₂ a ₀₃ )
(0 001) → 00
(0 010) → 01
(0 100) → 10
(1000) → 11
[0060]
Then, a ₁₀ ~ A _Thirteen , A ₂₀ ~ A ₂₃ , A ₃₀ ~ A ₃₃ In the same manner as described above, and by arranging the obtained 2-bit values in order from the left, an 8-bit maker ID can be obtained.
[0061]
In the case of the arrangement state of the inspection dots shown in FIG.
Manufacturer ID = 0,1,0,1,1,1,0,0 (binary number) = 92 (decimal number)
It becomes. This maker ID has a unique number for each maker. It can be specified that copying machines and printers manufactured by 92 manufacturers have formed the image.
[0062]
Next, a method of analyzing the area 305 representing the model number will be described. Note that the dot arrangement points existing in the area 305 are a ₀₄ , A ₀₅ ~ A ₄₄ , A ₄₅ , Which is a total of 10 dot arrangement points.
[0063]
Dot arrangement point a on main scanning line 0 in area 305 ₀₄ , A ₀₅ Are controlled so that one of them becomes 1 (with dots) and the other becomes 0 (without dots). Therefore, a ₀₄ , A ₀₅ 1-bit information can be represented by the presence or absence of the dot.
[0064]
In addition, points on the main scanning lines 1, 2, and 3 are similarly controlled. Therefore, the above eight points a ₀₄ , A ₀₅ ~ A ₃₄ , A ₃₅ Represents 4-bit information.
[0065]
Also, a on the main scanning line 4 ₄₄ , A ₄₅ Is a point for parity check.
[0066]
FIG. 6 is a diagram for explaining a method of parity check on information (model number) in area 305. a ₀₄ ~ A ₄₅ Are arranged as shown in the figure. ₄₄ , A ₄₅ Is an even parity in the direction of the arrow in the figure. If an error occurs in this parity check, the inspection dot is read again.
[0067]
On the other hand, if no error occurs in the parity check, a ₀₄ , A ₀₅ Is converted to a 1-bit value as follows according to the value of
(A ₀₄ a ₀₅ )
(01) → 0
(10) → 1
[0068]
Then, a ₁₄ ~ A _Fifteen , A ₂₄ ~ A ₂₅ , A ₃₄ ~ A ₃₅ , And the obtained 1-bit values are arranged in order from the left to obtain a 4-bit model number.
[0069]
In the case of the arrangement state of the inspection dots shown in FIG.
Model number = 1, 0, 0, 1 (binary) = 9 (decimal)
It becomes.
[0070]
Next, a method of analyzing an area representing a machine number and other information will be described.
[0071]
Six points a on the main scanning line 5 ₅₀ ~ A ₅₅ Are controlled so that only two points are 1 (dots present), and the other four points are 0 (no dots). Therefore, 15 kinds of information can be shown by the above 6 points.
[0072]
Similar control is performed for points on the main scanning lines 6 to 10. Therefore, by using the main scanning lines 5 to 10, 15 ⁶ Street information.
[0073]
Note that a on the main scanning line 11 ₁₁₀ ~ A ₁₁₅ Is a point for parity check.
[0074]
FIG. 7 is a diagram for explaining a parity check method for information (machine number and other information) in this area. a ₅₀ ~ A ₁₀₅ Are arranged as shown in the figure. ₁₁₀ ~ A ₁₁₅ Is an even parity in the direction of the arrow in the figure. If an error occurs in the parity check, the inspection dot is read again.
[0075]
On the other hand, if no error occurs in the parity check, a ₅₀ ~ A ₅₅ Is converted to a hexadecimal number as follows.
(A ₅₀ a ₅₁ a ₅₂ a ₅₃ a ₅₄ a ₅₅ )
(00 001 1) → 0
(00 010 1) → 1
(00 011 0) → 2
(00 100 1) → 3
(00 1010) → 4
(00 110 0) → 5
(01 000 1) → 6
(01001 0) → 7
(01010 0) → 8
(01 100 1) → 9
(10 000 1) → A
(10 001 0) → B
(10010) → C
(10 100 0) → D
(110000) → E
[0076]
Then, a ₆₀ ~ A ₆₅ , A ₇₀ ~ A ₇₅ , A ₈₀ ~ A ₈₅ , A ₉₀ ~ A ₉₅ , A ₁₀₀ ~ A ₁₀₅ In the same manner as above, and the obtained hexadecimal numbers are arranged in order from the left, so that the six-digit hexadecimal number is used as the machine number and other information. It is to be noted that, assuming that the maker of the present apparatus indicates the image processing mode with the upper one digit of the hexadecimal number and the lower five digits of the hexadecimal number with the machine number as shown in FIG. 4 of the present embodiment. In the case of inspection dot arrangement
Image processing mode = 0 (decimal number) = 0 (decimal number)
Aircraft number = 0, E, 7, 8, 1 (decimal number) = 48946 (decimal number)
It becomes.
[0077]
Note that the model number, machine number, and other information are numbers uniquely set by each manufacturer, and the amount of each information can be increased. For example, if the machine number is insufficient depending on the manufacturer, it is possible to add sub-scan lines 12, 13 etc. in order to increase the dot arrangement points. It can be expressed in base numbers.
[0078]
In the present embodiment, the number of test dots (dots present: 1) existing on each main scanning line of each area in the test block 201 is defined in order to prevent the dot density in the test block 201 from extremely increasing or decreasing. Was. That is, the adjustment is performed such that the number of inspection dots existing on each main scanning line in the inspection block 201 becomes two. However, the arrangement of dots in an area other than the area 305 representing the maker ID may be freely set by each maker. However, in this case as well, the main scanning line 4 and the main scanning line (main scanning line 11 in the present embodiment) located at the lowermost end of the check block are lines on which check dots for parity check are arranged. Is also defined by the above method.
[0079]
FIG. 8 is a schematic diagram of the inside of the image processing unit 1000 of FIG.
[0080]
In the figure, reference numeral 801 denotes an image input unit for inputting RGB multivalued color image data from an external device such as a host computer or another device inside the device in a frame-sequential manner.
[0081]
An image processing unit 802 performs well-known color correction processing and the like on the RGB multi-valued color image data input from the image input unit 801, converts the data into MCYK multi-valued color image data, and outputs the data in a frame-sequential manner to a subsequent stage. It is.
[0082]
An inspection dot addition processing unit 803 adds the above-described additional information (inspection dots) only to the Y component of the input MCYK multi-valued color image data. It should be noted that the M, C, and K planes are output to the subsequent stage without adding test dots.
[0083]
Reference numeral 804 converts the MCYK multi-valued color image data input in a frame-sequential manner into binary image data by PWM processing, and outputs the binary image data to the laser light emitting unit 1001 described above.
[0084]
FIG. 9 is an internal configuration diagram of the inspection dot addition processing unit 803 in FIG.
[0085]
The EEPROM 901 stores, in advance, additional information (a maker ID, a model number, a machine number, and the like) to be added to an image. The additional information (such as maker ID, model number, and machine number) is automatically loaded into the register 902 in the CPU 910 when the power of the image processing apparatus is turned on.
[0086]
Note that, in addition to the above-described additional information, a fixed bit in which a fixed value is entered and a parity bit for parity check are also stored in the register 902.
[0087]
First, when the image recording apparatus receives a command to print a color image, the above-described additional information is input to the encryption circuit 905 and encrypted.
[0088]
The encrypted additional information is input to the parity check circuit 906, where the parity and fixed bits are checked. If an error occurs here, it is determined that the additional information has been altered, and control is performed to forcibly stop the printing operation.
[0089]
The main scanning counter 907 performs a counting operation according to a clock signal PCLK in the main scanning direction of the image data, and sends ON at a position where a check dot is to be added according to a code loaded from the parity check 906.
[0090]
The sub-scanning counter 908 performs a counting operation in accordance with the clock signal BD in the sub-scanning direction, and sends ON at a main scanning line to which a test dot is to be added and a line at which a reference mark 202 is to be added.
[0091]
The inspection dot generation circuit 909 reads out inspection dot shape parameters stored in the ROM 903 in the CPU. Further, the inspection dot generation circuit 909 outputs a permission signal that turns on when a Y (yellow) plane is input to the test dot addition circuit 904 and a permission signal that turns on both the main scanning counter 907 and the sub-scanning counter 908. By inputting, the position where the test dot is added is determined, and the test dot having the shape indicated by the test dot shape parameter is generated at this position. Then, an additional signal corresponding to the image position to which the inspection dot is added is turned on and output. Note that the additional signals corresponding to the other image positions of the yellow plane and the image positions of the M, C, and K planes are turned off and output.
[0092]
The test dot adding circuit 904 outputs the multivalued image data as it is if the additional signal is OFF with respect to the input multivalued image data (yellow). After being converted to pixel values, they are output. This makes it possible to add additional information (reference marks and test dots in a test block) as shown in FIG.
[0093]
Note that the CPU 910 in FIG. 9 may be prepared to control only the inside of the test dot adding circuit 904, or may share the CPU that controls the entire image processing unit 1000. Also, a common memory that can store other information related to the image processing unit 1000 may be applied to the EEPROM 901.
[0094]
Next, an operation procedure for decoding the additional information will be described with reference to a flowchart of FIG.
[0095]
When the decoding process of the additional information is started, first, in step S1, a color image is read by a scanner. Since the additional information according to the present embodiment is added only to the yellow plane, only the yellow plane is read.
[0096]
Next, the reference mark 202 is detected (step S2), and the distance l between the dots is determined from the positional relationship between the three dots constituting the reference mark 202. Further, the direction of the inspection block 201 and the start position of the inspection block 201 are specified (Step S3).
[0097]
Next, the reference marks 202 adjacent to each other in the main scanning direction and the sub-scanning direction are extracted, and the distance L between the reference marks 202 is measured (step S4). At this point, the number of the main scanning and sub-scanning lines where the above-described dot arrangement points 303 exist and the dot arrangement points 303 can be specified, so that the dot arrangement points are specified (step S5).
[0098]
Next, the area 304 representing the maker ID is inspected (step S6), and the parity check of FIG. 5 is executed (step S7). If an error occurs, the inspection is repeated from the inspection of the maker ID area (step S6). On the other hand, if no error occurs, a maker ID is obtained (step S8).
[0099]
Next, the above-described area 305 representing the model number is checked (step S9), and the parity check shown in FIG. 6 is performed (step S10). If an error occurs, the model number area is checked again (step S9). On the other hand, if no error occurs, a model number is obtained (step S11).
[0100]
Next, the area indicating the machine number and other information is checked (step S12), and the parity check shown in FIG. 7 is performed (step S13). If an error occurs, the area is checked again (step S12). . On the other hand, if no error occurs, the device number and other information are obtained (step S14).
[0101]
Through the above steps, the additional information can be decrypted.
[0102]
Note that, in the present embodiment, as described above, the method of arranging the test dots is assumed to be the same for each maker for each maker, so that the decoding can be performed in a series of steps as shown in FIG. Was. However, when the number of inspection dots arranged on the main scanning lines (corresponding to the main scanning lines 5 to 11 in FIG. 4) in the inspection block 201 varies from manufacturer to manufacturer, the decoding is performed in the above series of steps ( No additional information can be obtained in steps S10 and S13). In this case, only the parity check such as the model number and the machine number is performed in steps S10 and S13, and the decoding module such as the model number and the machine number corresponding to the maker ID (manufacturer) obtained in step S7 is linked. And start it.
[0103]
In the present embodiment, the distance 2l between the dot arrangement points 303 is represented based on the distance l between the three dots in the reference mark 202. However, the arrangement of the three dots in the reference mark 202 is analyzed. Thus, the distance between the dot arrangement points 303 and the number of main scanning and sub-scanning lines where the dot arrangement points 303 exist may be specified. For example, the distance between the dot arrangement points 303 in the main scanning direction and the sub-scanning direction may be set to 3l + α by using l as the distance between the three dots in the main scanning direction and the sub-scanning direction.
[0104]
FIG. 11 shows an example of the shape of the inspection dot arranged at the dot arrangement point 303. Each inspection dot is composed of 4 × 4 pixels.
[0105]
At the center of each inspection dot in FIG. 7A, there is a region where the original image (only the yellow plane) is converted to the highest density FF, and at both ends there is a region where the minimum density is converted to 00. I do. In the case of (a), since the density difference between the central portion and both ends is large, the presence of the inspection dot can be easily recognized.
[0106]
In the center of each inspection dot in (b) in the figure, there is an area in which the original image (only the yellow plane) is converted by + α, and at both ends, an area in which the density is converted by -α. Exists. In the case of (b), since the density difference between the center and both ends is not as large as that of (a), there is a problem that the recognition probability of the inspection dot is reduced. However, it is substantially different from the original image (yellow plane). The advantage is that the concentration is preserved. Therefore, even if only the yellow plane is viewed, the deterioration of the image quality is reduced.
[0107]
According to the above embodiment, the additional information can be added to the input image in a manner that is difficult for the human eye to identify, and the information regarding the addition method is also added in a manner that is difficult for the human eye to identify. The additional information can be reliably decoded.
[0108]
In particular, when it is necessary for each device of a plurality of manufacturers to decode additional information from every image to which additional information is added, and when the shape of the inspection block 201 in FIG. Since the identifiable information is added, the shape of the inspection block 201 can be reliably determined on the decoding side, and the additional information can be reliably decoded.
[0109]
(Modification)
The present invention can be applied as a part of a system including a plurality of devices (for example, a host computer, an interface device, a reader, a printer, and the like), and can be configured as a single device (for example, a copying machine or a facsimile machine). May be applied.
[0110]
In addition, the present invention is not limited to only the apparatus and method for realizing the above-described embodiment, and a computer (CPU or MPU) in the system or apparatus is provided with software for realizing the above-described embodiment. The present invention also includes a case where the above-described embodiment is realized by supplying the program code of the wear and causing the computer of the system or the apparatus to operate the various devices according to the program code.
[0111]
In this case, the program code of the software implements the functions of the above-described embodiment, and the program code itself and means for supplying the program code to a computer, specifically, the program code Is included in the scope of the present invention.
[0112]
As a storage medium for storing such a program code, for example, a floppy disk, hard disk, optical disk, magneto-optical disk, CD-ROM, magnetic tape, nonvolatile memory card, ROM, or the like can be used.
[0113]
In addition to the case where the computer controls various devices in accordance with only the supplied program code to realize the functions of the above-described embodiment, the computer may execute the OS (Operating System) operating on the computer. Such a program code is also included in the scope of the present invention when the above-described embodiment is realized in cooperation with a system) or other application software.
[0114]
Further, after the supplied program code is stored in the memory provided in the function expansion board of the computer or the function expansion unit connected to the computer, the program code is stored in the function expansion board or the function storage unit based on the instruction of the program code. The present invention also includes a case where a provided CPU or the like performs a part or all of the actual processing, and the above-described embodiment is realized by the processing.
[0115]
【The invention's effect】
As described above, according to the present invention, in a technique of adding additional information as a dot pattern to an input image, even when different dot patterns are added to an image by a plurality of manufacturers or devices of a plurality of models, The shape of each dot pattern can be easily decoded.
[Brief description of the drawings]
FIG. 1 is a diagram showing an image processing apparatus used in the present embodiment.
FIG. 2 is a layout diagram of an inspection block and a reference mark.
FIG. 3 is a diagram for explaining a configuration of an inspection block in detail;
FIG. 4 is a diagram illustrating an example of adding a test dot in a test block;
FIG. 5 is a diagram for explaining a parity bit of a maker ID;
FIG. 6 is a diagram for explaining a parity bit of a model number;
FIG. 7 is a diagram for explaining a parity bit of a machine number;
FIG. 8 is an internal configuration diagram of an image processing unit 1000;
FIG. 9 is a block diagram of a test dot addition processing unit.
FIG. 10 is a flowchart showing a procedure for decoding additional information from an image to which additional information has been added.
FIG. 11 is a diagram showing an example of the shape of a test dot.
[Explanation of symbols]
100 photosensitive drum
101 charger
102 transfer drum
103 Cleaner
1000 Image processing unit

Claims (4)

A predetermined additional information is added to the input image, and a dot pattern composed of a plurality of dots is added to each unit area so that it is difficult for human eyes to recognize, and the plurality of dots may exist in the unit area. Means for adding a reference pattern for specifying each dot arrangement point having a characteristic to the human eyes so as to be difficult to recognize,
An image processing apparatus comprising output means for outputting an image to which predetermined additional information has been added by said adding means. The image processing apparatus according to claim 1 , wherein the reference pattern indicates a distance between adjacent dot arrangement points. A predetermined additional information is added to the input image, and a dot pattern composed of a plurality of dots is added to each unit area so that it is difficult for human eyes to recognize, and the plurality of dots may exist in the unit area. An additional step of adding a reference pattern for identifying each dot arrangement point having a characteristic to the human eyes so as to be difficult to identify;
An image processing method comprising an output step of outputting an image to which predetermined additional information has been added by said adding means. A predetermined additional information is added to the input image, and a dot pattern composed of a plurality of dots is added to each unit area so that it is difficult for human eyes to recognize, and the plurality of dots may exist in the unit area. An additional step of adding a reference pattern for identifying each dot arrangement point having a characteristic to the human eyes so as to be difficult to identify;
A storage medium storing an image processing program in a state readable by a computer, comprising an output step of outputting an image to which predetermined additional information has been added by said adding means.

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