JP3679571B2 - Image processing apparatus and method, and storage medium - Google Patents

Description

[0001]
BACKGROUND 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]
In recent years, image recording apparatuses such as color printers and color copiers have been able to form high-quality images due to improved performance. Under such circumstances, it is becoming possible to form an image similar to securities such as banknotes, and a technique for preventing such an action is 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 color image to be printed so that it is difficult to be recognized by human eyes.
[0004]
Usually, this dot pattern has a predetermined size, and a plurality of dots are arranged within this predetermined size. Additional information can be expressed by the arrangement of the plurality of dots. The dot pattern is periodically printed on the entire screen. In addition, when a dot pattern is added to a color image composed of yellow, magenta, cyan, and black planes in order to make it difficult for human eyes to identify, the dot pattern is added only to the yellow plane.
[0005]
By performing the above addition, when an image that should be prohibited from image formation or a copy image that should be prohibited from copying appears, the additional information (machine number) is decoded from these images, and these It becomes possible to specify the device that formed the image.
[0006]
[Problems to be solved by the invention]
However, when the additional information is decoded from the image formed after adding the additional information to the image as described above, it is difficult or impossible to decode depending on the environment of the image forming apparatus and the content of the image. Some parts were generated. Therefore, for example, when a plurality of additional information having different importance levels exist as the additional information, only the additional information with a higher importance level may be unreadable.
[0007]
The present invention has been made in view of the above-described conventional example, and when adding a plurality of additional information having different importance levels to an input image that is difficult to be identified by the human eye, The purpose is to provide a technology that can reliably decode additional information of high importance.
[0008]
[Means for Solving the Problems]
  In order to solve the above-described problem, according to the image processing apparatus of the present invention, the first pattern representing the manufacturer of the apparatus for the input image (in this embodiment, two sub-blocks 1401 representing the manufacturer ID in FIG. 14). ) And a second pattern representing other additional information (also corresponding to six sub-blocks 1401 representing the machine number, image processing type, and model number in FIG. 14). 2 is added to the inspection dot addition processing unit 803 in FIG. 8 in a manner that periodically adds the region 201 in FIG. 2 or the region composed of 2 × 4 sub-blocks in FIG. And output means for outputting an image to which predetermined additional information is added by the adding means (also corresponding to the PWM processing unit 804 in FIG. 8). That) has, in each of the unit dot pattern, At least one second pattern exists,A plurality of the first patterns are present adjacent to each other (also corresponding to the case where two sub-blocks 1401 representing a manufacturer ID are adjacent in FIG. 14), and the plurality of first patterns have the same content ( It also represents the same as the manufacturer ID).
[0009]
DETAILED DESCRIPTION OF THE INVENTION
(First embodiment)
In this embodiment mode, an image recording apparatus using a color electrophotographic technique is described. However, the present invention is not limited to this, and can also be applied to an image processing apparatus using a technique such as an inkjet method or a thermal transfer method.
[0010]
In this embodiment, the input image data is multi-valued image data of 8 bits for each color of M (magenta), C (cyan), Y (yellow), and BK (black). Input in frame order.
[0011]
The image recording apparatus (laser beam printer) of 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. In this way, it is possible to make it difficult for human eyes to identify as much as possible, and even a color image with additional information added can be used in the same manner as the original color image before adding the additional information. Is possible. The present invention is not limited to the case where additional information for forgery tracking is added. In other words, the present invention includes a case where the name of the author who created the original image or the work name of the image is used as additional information.
[0012]
FIG. 1 shows the configuration of an image processing apparatus used in the following embodiments.
[0013]
An image processing unit 1000 sequentially inputs multi-value image data composed of R, G, and B from an external device or another device inside the apparatus, and multi-value image data composed of M, C, Y, and K. After adding additional information, which will be described later, only to the Y component of the multi-value image data, the multi-value image data of each color is converted into binary image data by PWM processing, and then the laser emission unit 1001 Output to. The laser light emitting unit 1001 emits a laser beam L described later based on the input binary image data.
[0014]
The photosensitive drum 100 is uniformly charged to a predetermined polarity by the charger 101, and a magenta first latent image, for example, is formed on the photosensitive 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 the magenta latent image, and a magenta first toner image is formed on the photosensitive drum 100.
[0015]
On the other hand, the transfer paper P is fed at a predetermined timing, and immediately before the leading edge reaches the transfer start position, a transfer bias voltage (+1.8 KV) having a polarity opposite to that of the toner (for example, plus polarity) is applied to the transfer drum 102. Then, the first toner image on the photosensitive drum 100 is transferred to 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 to prepare for the next color latent image formation and development process.
[0016]
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 a second developer image on the photosensitive drum 100 is formed by the cyan developing device Dc. The latent image is developed to form a cyan second toner image.
[0017]
The cyan second toner image is transferred onto the transfer paper P in accordance with the position of the first magenta toner image transferred onto the transfer paper P. In transferring 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.
[0018]
Similarly, the yellow and black third and fourth latent images are sequentially formed on the photosensitive drum 100, and are sequentially developed by the developing devices Dy and Db, respectively, and transferred to the transfer paper P in advance. 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 the four color toner images are superimposed on the transfer paper P is formed.
[0019]
Next, additional information added by the image processing apparatus according to the present embodiment will be described.
[0020]
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. In the present embodiment, as described above, additional information (dot pattern) is added only to the Y plane, so FIG. 2 shows a color composed of Y, M, C, and K planes. An image indicated by a Y plane of the image is shown.
[0021]
In the drawing, an area 201 indicated by shading 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 areas 201 are periodically present in the color image (yellow plane) as shown in the figure. In this way, the additional information can be analyzed with reference to any region of the color image finally formed after the additional information is added. Hereinafter, this unit area 201 is referred to as an inspection block.
[0022]
The three dots 202 are called reference marks and indicate the starting position of each inspection block 201 and the main scanning and sub-scanning directions. Further, the reference mark 202 has some information, which will be described later in detail.
[0023]
Each inspection block 201 has a plurality of dots having a very small area composed of a plurality of pixels, which will be described later, and additional information can be expressed by the arrangement method of each dot. Hereinafter, this dot is referred to as an inspection dot.
[0024]
FIG. 3 is a diagram showing in detail the inspection block 201 of FIG.
[0025]
In the inspection block 201, guide lines 301 and 302 exist vertically and horizontally, the vertical direction (sub-scanning direction) line 301 is the sub-scanning line, and the horizontal direction (main-scanning direction) line 302 is the main scanning line. Call it. In this embodiment, there are 0, 1,.
[0026]
The circles indicated by 303 are points where inspection dots may be arranged, and in this embodiment, these points are the intersections of odd-numbered main scanning lines and even-numbered sub-scanning lines, and even-numbered lines. Exists at the intersection of the main scanning line and the odd-numbered sub-scanning line.
[0027]
Hereinafter, each point at which this inspection dot may be placed is denoted by 303 and is called a dot placement point. The additional information added to the image (yellow plane) can be expressed by whether or not the inspection dot is added to each dot arrangement point 303. The dot arrangement points 303 are configured to be separated from each other by a distance 2l in the main scanning direction and the sub scanning direction.
[0028]
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 (21) between the dot arrangement points 303 can be defined. Are each separated by a distance l. As a result, whatever the distance 2l between the adjacent dot arrangement points 303 is any value, it can be calculated from the distance l of the reference mark 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 is described as being the same. However, for example, each distance of the main scanning lines 0 to 11 is l, and the distance between the sub scanning lines 0 to 11 is A case where each distance is l ′ can be dealt with. In this case, the distance between two dots extending in the sub-scanning direction of the reference mark 202 may be changed to l ′.
[0029]
In the present embodiment, the three dots constituting the reference mark 202 and the shape of each inspection dot are the same.
[0030]
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, it can be seen that the size of the inspection block 201 in the main scanning direction and the sub-scanning direction is L−2 × l.
[0031]
As described above, the shape of the inspection block 201 can be calculated as long as the reference mark 202 can be decoded.
[0032]
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
[0033]
Note that the values of L, l, and n can be freely set for each manufacturer of each device and for each device model, and are adjusted according to the size of the inspection block 201, the dot density, and the amount of information to be embedded. Optimal settings can be made. Therefore, at the time of decoding, the reference mark 202 is detected, and by measuring the distances L and l, the position of the main scanning and sub-scanning lines and the position of the dot arrangement point can be specified, and the additional information is decoded. It becomes possible to do.
[0034]
In the present embodiment, the positional relationship between the three dots of the reference mark 202 is controlled so as not to appear between inspection blocks. Thereby, 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 arrangement state of the dots.
[0035]
Next, information represented by each dot arrangement point 303 will be described.
[0036]
In FIG. 3, an area 304 is an area for representing a manufacturer 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.
[0037]
An area 305 is an area for indicating a model name (printer type).
[0038]
The other area is an area for representing a machine number unique to each printer or some information relating to an added image.
[0039]
In the above three areas, a part is a point for indicating the above information, and another part is a point for adding a parity bit.
[0040]
In this embodiment, the number of main scanning and sub-scanning lines where the dot arrangement point 303 exists is 12 lines. However, as described above, the number of lines can also be determined based on the reference mark 202. It can be set freely for each model.
[0041]
Next, referring to FIG. 4, a procedure for decoding the additional information added to the image based on the image formed by the image processing apparatus will be described, and a method for expressing the additional information will be described.
[0042]
First, the inspection dot is decoded by, for example, reading a color image to which additional information is added with a scanner, extracting only a Y (yellow) plane image to the host computer, and each position of the inspection dot on the monitor of the host computer. Do by confirming.
[0043]
First, the above-described reference mark 202 is detected. In FIG. 4, since the positional relationship of the three dots forming the reference mark 202 does not exist in the inspection block, the reference mark 202 can be easily determined.
[0044]
Next, the main scanning and sub-scanning directions of the inspection block are specified based on the positional relationship between the three dots constituting the reference mark 202.
[0045]
Further, based on the positional relationship of the three dots, the distance l between the main scanning lines where the dot arrangement point 303 exists and the distance l between the sub scanning lines are measured.
[0046]
Next, the size (L−2 × l) of the inspection block 201 is specified by measuring the distance L based on the positional relationship between a certain reference mark 202 and the reference mark 202 adjacent in the main scanning direction and the sub-scanning direction. To do.
[0047]
Next, based on the relationship of 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.
[0048]
Next, corresponding additional information is determined based on the presence or absence of dots at the dot arrangement points.
[0049]
Hereinafter, the dot arrangement points 303 on the main scanning line n are a in order from the left._n0, A_n1... a_n5In the following description, the case where inspection dots are arranged is 1 and the case where inspection dots are not arranged is 0.
[0050]
First, a method for analyzing the area 304 representing the manufacturer ID will be described. The dot arrangement points existing in the area 304 are a₀₀, A₀₁, A₀₂, A₀₃, ~ A₄₀, A₄₁, A₄₂, A₄₃There are a total of 20 dot arrangement points.
[0051]
In this embodiment, a is a dot arrangement point that exists on the main scanning line 0 in the region 304.₀₀, A₀₁, A₀₂, A₀₃Of the four points, only one point is controlled to be 1 (with dots), and the other three points are controlled to be 0 (without dots). That is, 2-bit information is represented by the above four points.
[0052]
Similar 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.
[0053]
In addition, a existing on the main scanning line 4₄₀, A₄₁, A₄₂, A₄₃Is a point for parity check.
[0054]
FIG. 5 is a diagram for explaining a parity check method for information (maker ID) in the area 304. a₀₀~ A₄₃Are arranged as shown, a₄₀, A₄₁, A₄₂, A₄₃Confirm that the parity becomes even parity in the direction of the arrow in the figure. If an error occurs in this parity check, the check dot is read again.
[0055]
On the other hand, if no error occurs in the parity check, a₀₀, A₀₁, A₀₂, A₀₃Is converted into the following 2-bit value according to the value of.
[0056]
(A₀₀  a₀₁  a₀₂  a₀₃)
(0 001) → 00
(0 010) → 01
(0 100) → 10
(1000) → 11
[0057]
Then, a_Ten~ A₁₃, A₂₀~ A_{twenty three}, A₃₀~ A₃₃An 8-bit maker ID can be obtained by converting into a 2-bit value in the same order as described above and arranging the obtained 2-bit values in order from the left.
[0058]
In the case of the inspection dot arrangement state shown in FIG.
Manufacturer ID = 0, 1, 0, 1, 1, 1, 0, 0 (binary number) = 92 (decimal number)
It becomes. Since this manufacturer ID has a unique number for each manufacturer, it can be identified that the copying machine or printer manufactured by the manufacturer No. 92 has formed the image.
[0059]
Next, a method for analyzing the area 305 representing the model number will be described. The dot arrangement points existing in the area 305 are a₀₄, A₀₅~ A₄₄, A₄₅There are a total of 10 dot arrangement points.
[0060]
Dot placement point a on main scan line 0 in region 305₀₄, A₀₅These two points are controlled so that one of them becomes 1 (with dots) and the other becomes 0 (without dots). Therefore, a₀₄, A₀₅One-bit information can be expressed by the presence or absence of dots.
[0061]
The points on the main scanning lines 1, 2, and 3 are similarly controlled. Therefore, the above eight points a₀₄, A₀₅~ A₃₄, A₃₅Represents 4-bit information.
[0062]
In addition, a on the main scanning line 4₄₄, A₄₅Is a point for parity check.
[0063]
FIG. 6 is a diagram for explaining a parity check method for information (model number) in the area 305. a₀₄~ A₄₅Are arranged as shown, a₄₄, A₄₅Confirm that the parity becomes even parity in the direction of the arrow in the figure. If an error occurs in this parity check, the test dot is read again.
[0064]
On the other hand, if no error occurs in the parity check, a₀₄, A₀₅Depending on the value of, it is converted to a 1-bit value as follows.
(A₀₄  a₀₅)
(01) → 0
(10) → 1
[0065]
Then, a₁₄~ A₁₅, A_{twenty four}~ A_{twenty five}, A₃₄~ A₃₅In this order, conversion is performed in the same manner as described above, and the obtained 1-bit values are arranged in order from the left to obtain a 4-bit model number.
[0066]
In the case of the inspection dot arrangement state shown in FIG.
Model number = 1, 0, 0, 1 (binary number) = 9 (decimal number)
It becomes.
[0067]
Next, a method for analyzing an area representing the machine number and other information will be described.
[0068]
Six points a on the main scanning line 5₅₀~ A₅₅Of these, only two points are controlled to be 1 (with dots), and the other four points are controlled to be 0 (without dots). Therefore, 15 kinds of information can be shown by the above 6 points.
[0069]
Similar control is performed for points on the main scanning lines 6-10. Therefore, using the main scanning lines 5 to 10, 15⁶It represents street information.
[0070]
Note that a on the main scanning line 11₁₁₀~ A₁₁₅Is a point for parity check.
[0071]
FIG. 7 is a diagram for explaining a parity check method for information (aircraft number and other information) in this area. a₅₀~ A₁₀₅Are arranged as shown, a₁₁₀~ A₁₁₅Confirm that the parity becomes even parity in the direction of the arrow in the figure. If an error occurs in this parity check, the check dot is read again.
[0072]
On the other hand, if no error occurs in the parity check, a₅₀~ A₅₅According to the value of, it is converted into a decimal number as follows.
(A₅₀  a₅₁  a₅₂  a₅₃  a₅₄  a₅₅)
(00 001 1) → 0
(00 010 1) → 1
(00 011 0) → 2
(00 100 1) → 3
(00 10 10) → 4
(00 110 0) → 5
(01 000 1) → 6
(01 001 0) → 7
(01 010 0) → 8
(01 100 0) → 9
(10 000 1) → A
(10 001 0) → B
(10 010 0) → C
(10 100 0) → D
(11 000 0) → E
[0073]
Then, a₆₀~ A₆₅, A₇₀~ A₇₅, A₈₀~ A₈₅, A₉₀~ A₉₅, A₁₀₀~ A₁₀₅In this order, conversion is performed in the same manner as described above, and the obtained 15-digit numbers are arranged in order from the left, so that the 6-digit number is used as the machine number and other information. Assuming that the manufacturer constituting this apparatus represents the first 1-digit decimal number as the image processing mode, and represents the machine number as the lower 5-digit 15-digit number, it is shown in FIG. 4 of the present embodiment. In 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.
[0074]
Note that the model number, machine number, and other information are numbers uniquely set by each manufacturer, and each information amount can be increased. For example, if the machine number is not enough depending on the manufacturer, it is possible to add sub-scanning lines 12, 13 etc. in order to increase the dot arrangement points. It can be expressed in decimal.
[0075]
In the present embodiment, the number of inspection dots (with dots: 1) existing on each main scanning line in each region in the inspection block 201 is specified in order not to extremely increase or decrease the dot density in the inspection block 201. Was. That is, the adjustment is made so that the number of inspection dots existing on each main scanning line in the inspection block 201 is two. However, the dot arrangement in the area other than the area 305 representing the manufacturer ID may be freely set by each manufacturer. In this case, however, the main scanning line 4 and the main scanning line (main scanning line 11 in this embodiment) positioned at the lowermost end of the inspection block are lines on which inspection dots for parity check are arranged, and a parity check method is used. Is also defined by the above method.
[0076]
FIG. 8 is a schematic diagram of the inside of the image processing unit 1000 of FIG.
[0077]
In the figure, reference numeral 801 denotes an image input unit for inputting RGB multi-value color image data in a frame sequential manner from an external device such as a host computer or another device inside the apparatus.
[0078]
An image processing unit 802 performs known color correction processing on the RGB multi-value color image data input from the image input unit 801, converts the data into MCYK multi-value color image data, and outputs the converted data to the subsequent stage in a frame sequential manner. It is.
[0079]
Reference numeral 803 denotes an inspection dot addition processing unit that adds the above-described additional information (inspection dots) only to the Y component in the input multi-value color image data of MCYK. The M, C, and K planes are output as they are without adding inspection dots.
[0080]
804 converts MCYK multi-valued color image data input in frame sequential order into binary image data by PWM processing, and outputs the binary image data to the laser light emitting unit 1001 described above.
[0081]
FIG. 9 is an internal configuration diagram of the inspection dot addition processing unit 803 in FIG.
[0082]
The EEPROM 901 stores in advance additional information (maker ID, model number, machine number, etc.) to be added to the image. The additional information (manufacturer ID, model number, machine number, etc.) is automatically loaded into the register 902 in the CPU 910 when the image processing apparatus is turned on.
[0083]
In addition to the above-described additional information, the register 902 also stores a fixed bit that contains a fixed value and a parity bit for parity check.
[0084]
First, when the image recording apparatus receives a command to print a color image, the additional information described above is input to the encryption circuit 905 and encrypted.
[0085]
This encrypted additional information is input to the parity check circuit 906, where parity and fixed bits are checked. If an error occurs, it is determined that the additional information has been modified, and control is performed to forcibly stop the printing operation.
[0086]
The main scanning counter 907 performs a counting operation according to the clock signal PCLK in the main scanning direction of the image data, and sends ON at a position where a test dot is to be added according to the code loaded from the parity check 906.
[0087]
The sub-scanning counter 908 performs a counting operation in accordance with the clock signal BD in the sub-scanning direction, and sends ON on the main scanning line to which the inspection dot is to be added and the line to which the reference mark 202 is to be added.
[0088]
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 receives a permission signal that is turned on when a Y (yellow) plane is input to the inspection 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 to add the inspection dot is determined, and the inspection dot having the shape indicated by the inspection 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 image positions of the other yellow planes and the image positions of the M, C, and K planes are turned OFF and output.
[0089]
The inspection dot addition circuit 904 outputs the multi-value image data as it is if the additional signal is OFF with respect to the input multi-value image data (yellow), and if the additional signal is ON, the inspection dot is added. Output after converting to pixel value. Accordingly, additional information (reference mark and each inspection dot in the inspection block) as shown in FIG. 4 can be added.
[0090]
Note that the CPU 910 in FIG. 9 may be prepared for controlling only the inspection dot addition circuit 904, or may share the CPU that controls the entire image processing unit 1000. Further, a common memory that can store other information related to the image processing unit 1000 may also be applied to the EEPROM 901.
[0091]
Next, the operation procedure for decoding the additional information will be described with reference to the flowchart of FIG.
[0092]
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 of this embodiment is added only to the yellow plane, only the yellow plane is read.
[0093]
Next, the reference mark 202 is detected (step S2), and the distance l between the dots is determined from the positional relationship of 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).
[0094]
Next, reference marks 202 adjacent to each other are extracted in the main scanning direction and the sub-scanning direction, and the distance L between the reference marks 202 is measured (step S4). At this time, since the number of main scanning and sub-scanning lines where the dot arrangement point 303 described above exists and the dot arrangement point 303 can be specified, the dot arrangement point is specified (step S5).
[0095]
Next, the above-described area 304 representing the manufacturer ID is inspected (step S6), the above-described parity check in FIG. 5 is performed (step S7), and if the error is detected, the process is restarted from the inspection of the manufacturer ID area (step S6). On the other hand, if no error occurs, the manufacturer ID is acquired (step S8).
[0096]
Next, the above-described area 305 representing the model number is inspected (step S9), the parity check in FIG. 6 is performed (step S10), and if there is an error, the model number area is inspected again (step S9). On the other hand, if no error occurs, the model number is acquired (step S11).
[0097]
Next, the above-described region representing the machine number and other information is inspected (step S12), the above-described parity check in FIG. 7 is performed (step S13), and if there is an error, the above-described region inspection (step S12) is performed again. . On the other hand, if no error occurs, the machine number and other information are acquired (step S14).
[0098]
The additional information can be decoded by the above steps.
[0099]
In the present embodiment, as described above, it is assumed that the method of arranging inspection dots is the same for each maker as described above, so that it can be decoded in a series of steps as shown in FIG. It was. However, when the number of inspection dots arranged on the main scanning line (corresponding to the main scanning lines 5 to 11 in FIG. 4) in the inspection block 201 is different for each manufacturer, it is decoded in the above series of steps ( Additional information cannot be obtained in steps S10 and S13. In this case, only the parity check of the model number, machine number, etc. is performed in steps S10 and S13, and the model number, machine number, etc. decoding module corresponding to the manufacturer ID (manufacturer) obtained in step S7 is linked. And start it.
[0100]
In the present embodiment, the distance 21 between the dot arrangement points 303 is expressed 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. Accordingly, 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 3l + α by using l as the distance of the three dots in the main scanning direction and the sub-scanning direction.
[0101]
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.
[0102]
In the figure, at the center of each inspection dot, there is a region where the original image (only the yellow plane) is converted to the highest density FF, and there are regions where both ends are converted to the lowest density 00. To do. In the case of (a), since the density difference between the central portion and both ends thereof is large, the presence of the inspection dot can be easily recognized.
[0103]
Also, in the center of each inspection dot in (b) in the figure, there is a region where the original image (only the yellow plane) is density-converted by + α, and at both ends there are regions where the density is converted by −α. Exists. In the case of (b), the density difference between the central portion and both ends thereof is not so large as in (a), so there is a problem that the recognition probability of the inspection dot is lowered, but it is substantially less than the original image (yellow plane). The advantage is that the concentration is preserved. Therefore, even when only the yellow plane is viewed, deterioration in image quality is reduced.
[0104]
According to the above embodiment, the additional information can be added to the input image so that it is difficult to be identified by the human eye, and the information regarding the addition method is also difficult to be identified by the human eye. The additional information can be reliably decoded.
[0105]
In particular, when it is necessary for each device of a plurality of manufacturers to decode additional information from any image to which additional information has been added, if 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.
[0106]
(Second Embodiment)
In the above embodiment, two to four test dots are added side by side at the parity check check dot arrangement point (intersection of the main scanning line 4 and the sub-scanning lines 1, 3, 5, and 7 in FIG. 3). It may be done. In this case, the presence of these inspection dots may be noticeable.
[0107]
In this embodiment, the arrangement of inspection dots is controlled so as not to increase the density at which inspection dots are added in the inspection block as much as possible. Since the apparatus configuration is the same as that of the first embodiment, description thereof is omitted.
[0108]
12 and 13 show examples of the arrangement of inspection dots according to the present embodiment.
[0109]
In the present embodiment, there is no inspection dot arrangement point for parity check as shown in FIG. The manufacturer ID area 304 includes main scanning lines 0 to 3 and sub scanning lines 0 to 7, and 16 dot arrangement points exist in the area 304. A on main scan line n_n0~ A_n3Of the four points (n = 0, 1, 2, 3), only one point is set to 1 (with dots), and the other three points are controlled to be 0 (without dots).
[0110]
Furthermore, a for the sub-scanning direction_0n~ A_3nOf the four points (n = 0, 1, 2, 3), the number of dots that become 1 (with dots) is always controlled to be an even number.
[0111]
By controlling the dot arrangement method as described above, the manufacturer ID area 304 can represent 40 types of information, and up to 40 manufacturers can be identified from the dots added to the area 304.
[0112]
A when deciphering_0n~ A_3nConfirm that the sum of (n = 0, 1, 2, 3) is an even number. This is exactly the same operation as the parity check in the above-described embodiment.
[0113]
If the error rate of inspection dot discrimination at the time of decoding is p,
False detection rate of manufacturer ID ≦ about 18 × p^Four× (1-p)¹²
Thus, the probability of false detection is very low.
[0114]
Next, dot arrangement control in the area 305 representing the model number will be described. The dot arrangement point existing in the area 305 is a₀₄, A₀₅~ A₃₄, A₃₅There are a total of eight.
[0115]
Dot arrangement point a on main scanning line n in region 305_n4, A_n5Two points (n = 0, 1, 2, 3) are controlled so that one of them becomes 1 (with dots) and the other becomes 0 (without dots). For the sub-scanning direction, a_0n~ A_3nOf the four points (n = 4, 5), the number of dots that become 1 (with dots) is controlled to be an even number.
[0116]
By controlling the dot arrangement method as described above, the model number area 304 can represent eight types of information, and eight models can be identified. A when deciphering_0n~ A_3nConfirm that the sum of (n = 4, 5) is an even number.
[0117]
Also, the false detection rate of model number is
Model number false detection rate = approx. 6 x p^Four× (1-p)^Four
It becomes.
[0118]
Next, the dot arrangement control of the area representing the machine number and other information will be described.
[0119]
Six dot arrangement points a on the main scanning line n_n0~ A_n5Of (n = 4 to 11), only two points are controlled to be 1 (with dots), and the other four points are controlled to be 0 (without dots). For the sub-scanning direction, a_n4~ A_n11Of the eight points (n = 0 to 5), the number of dots that become 1 (with dots) is controlled to be an even number.
[0120]
By controlling the dot arrangement method as described above, information necessary for the manufacturer can be expressed in this area.
[0121]
A when deciphering_n4~ A_n11Confirm that the sum of (n = 0 to 5) is an even number.
[0122]
The false positive rate in this area is
False detection rate ≦ about 224 × p^Four× (1-p)⁴⁴
It becomes.
[0123]
According to the above embodiment, since the density at which inspection dots are added in the inspection block can be made constant regardless of the contents such as the manufacturer ID, model number, number unique to each device, etc. The probability of false detection at the time of decoding can be reduced.
[0124]
In the second embodiment, the quality of the final formed image is improved by not adding a parity check dot. However, the present invention is not limited to this, and the number of parity check dots is not limited thereto. It is also possible to only control the dot arrangement method so as to reduce as much as possible.
[0125]
That is, with respect to the region 304, a point a where a parity check dot should be arranged as shown in FIG._5n(N = 0 to 3) is ensured, and a dot arrangement (a that does not add a parity check dot to all four arrangement points)_5nA layout where dots are added to 0 to 3)₀₀~ A₀₄, A_Ten~ A₁₄, A₂₀~ A_{twenty four}, A₃₀~ A₃₄You may go against. In this way, at least a point a where parity check dots should be arranged a_5nSince four dots are not arranged at (n = 0 to 3), it is possible to maintain good image quality.
[0126]
Similarly, point a where a dot for parity check should be placed_5nControl (a) so that two or more or three or more are not added to (n = 0 to 3)_5nIt is also possible to perform control such that 0 to 1 or 0 to 2 dots are added to the above. In the second embodiment, the point a_5nControl (a) so that one or more are not added to (n = 0-3)_5nThis arrangement point a is controlled so that 0 dots are added to_5n(N = 0 to 3) itself is eliminated.
[0127]
The control of the dot arrangement method may be such that the data itself stored in the EEPROM 901 in FIG. 9 may be limited in advance, but the CPU 910 stores the data in the EEPROM 901 so that only the dot arrangement described above is executed. It is also possible to read by changing the interpretation method of the received data. Alternatively, it may be executed at the time of encryption in the encryption circuit 905.
[0128]
(Third embodiment)
Another embodiment of the present invention will be described. Since the apparatus configuration is the same as that of the first embodiment, description thereof is omitted.
[0129]
In the present embodiment, a plurality of the most important manufacturer IDs are included in a unit area (corresponding to the area 201 in FIG. 2) in which at least one of all additional information of the manufacturer ID, model number, and machine number is embedded. They are arranged.
[0130]
FIG. 14 shows an example of an inspection block according to the present embodiment.
[0131]
In this embodiment, as shown in the figure, a region 1401 formed by five main scanning lines and eight sub-scanning lines is used as one block unit, and this is called a sub-block. In this embodiment, a case where there are eight sub-blocks in a unit area (corresponding to the area 201 in FIG. 2) will be described. Details of each sub-block 1401 are shown in FIG.
[0132]
There are 16 dot placement points in the sub-block 1401 in FIG.
a₀₀ a₀₁ a₀₂ a₀₃
a_Ten a₁₁ a₁₂ a₁₃
a₂₀ a_{twenty one} a_{twenty two} a_{twenty three}
a₃₀ a₃₁ a₃₂ a₃₃
And
[0133]
The dots in the sub-block are a_n0~ A_n3Of the four points, only one point is controlled to be 1 (with dots), and the other three points are controlled to be 0 (without dots).
[0134]
Furthermore, a for the sub-scanning direction_0n~ A_3nOf the four points (n = 0, 1, 2, 3), the number of dots that become 1 (with dots) is always controlled to be an even number.
[0135]
By controlling the dot arrangement method as described above, the sub-block 1401 can represent 40 types of information.
[0136]
A when deciphering_0n~ A_3nConfirm that the sum of (n = 0, 1, 2, 3) is an even number. This is exactly the same work as the parity check in the first embodiment. Further, as a coding method, for example, numbers may be sequentially assigned to the 40 patterns so as to represent one digit of a 40-digit number.
[0137]
In the present embodiment, the inspection block is composed of 2 × 4 sub-blocks as shown in FIG.
[0138]
Of these, the sub-block closest to the reference mark represents the manufacturer ID. In addition, the sub-block located on the right side also represents the same content, that is, the manufacturer ID. Therefore, the two sub-blocks located in the uppermost row have the same dot arrangement. This is because the manufacturer ID, which is the most important information for decoding the inspection dot, is expressed in two places. Even if it is difficult to decode one of the sub-blocks, the other sub-block is decoded, so that the manufacturer ID This is to increase the reliability of decryption.
[0139]
In the present invention, as shown in FIG. 14, a plurality of manufacturer IDs (two in this embodiment) are arranged in the main scanning direction. It may be modified in any way according to the situation.
[0140]
For example, the inspection block may be spaced apart such as the upper left corner and the lower right corner. Further, three or four maker ID sub-blocks may be arranged to increase the maker ID reliability. Further, a plurality of manufacturer IDs may be arranged so as to be adjacent in an oblique direction. A plurality of manufacturer IDs may be arranged in the sub-scanning direction.
[0141]
Next, information indicated by other sub-blocks will be described. The other 2 × 3 sub-blocks represent independent information. For example, the left sub-block in the second column represents a model number, and the right sub-block represents a code indicating the type of image processing. The four sub-blocks in the third and fourth columns sequentially represent the four digits (40-digit number) of the machine number unique to the printer.
[0142]
In this way, a single unit area (check block) in which at least one of various additional information appears is divided into a plurality of sub-blocks, and independent information is expressed for each of the sub-blocks. Even if only a part can be recognized, a certain amount of information can be obtained only by a recognizable part.
[0143]
For example, even if only the left half of the inspection block can be decoded in FIG. 14, the highest digit and the third digit of the manufacturer ID, model number, and machine number can be decoded, and the device used for output can be narrowed down to some extent. Is possible. Furthermore, since this system has a parity check function for each sub-block, it is possible to improve the reliability of decoding.
[0144]
As described above, in the present embodiment, the manufacturer ID = 40, the model number = 40, the image processing number = 40, and the machine number = 40.^FourA street can be represented.
[0145]
The number of sub-blocks is fixed in two blocks in the main scanning direction, but the sub-scanning direction may vary depending on the manufacturer and model, and can be increased or decreased in units of one block in the sub-scanning direction.
[0146]
The dot arrangement described in the first, second, and third embodiments is a group (for example, a in FIG. 5 when a parity check is performed).₀₀~ A₃₀Or a₀₁~ A₃₁Etc.), the sum of the presence / absence of dots (1/0) is controlled to be an even number (even parity), but the present invention is not limited to this. That is, when executing the parity check, the arrangement of each dot may be controlled such that the sum of the presence / absence of dots (1/0) in the group is an odd number (odd parity). Whether to use the even parity or the odd parity may be appropriately determined according to the size of the area 201 in FIG. 2 or the amount of data to be added by adding additional information so as not to deteriorate the image quality. In addition, the parity bit of the manufacturer ID shown in FIG. 5 is an odd parity, and the parity number of the model number, machine number, and other information shown in FIGS. 6 and 7 is an even parity within one unit area 201. Parity and odd parity may be selectively used.
[0147]
(Modification)
Even if the present invention is applied as a part of a system composed of a plurality of devices (for example, a host computer, an interface device, a reader, a printer, etc.), an apparatus composed of a single device (for example, a copier, a facsimile machine). You may apply to one part of.
[0148]
In addition, the present invention is not limited only to the apparatus and method for realizing the above-described embodiment, and software for realizing the above-described embodiment on a computer (CPU or MPU) in the system or apparatus. A case in which the above-described embodiment is realized by supplying a software program code and causing the system or apparatus computer to operate the various devices according to the program code is also included in the scope of the present invention.
[0149]
In this case, the program code of the software itself realizes the function of the above embodiment, and the program code itself and means for supplying the program code to the computer, specifically, the program code Is included in the scope of the present invention.
[0150]
As a storage medium for storing such a program code, for example, a floppy disk, a hard disk, an optical disk, a magneto-optical disk, a CD-ROM, a magnetic tape, a nonvolatile memory card, a ROM, or the like can be used.
[0151]
Further, the computer controls various devices according to only the supplied program code, so that not only the functions of the above embodiments are realized, but also the OS (operating system) on which the program code is running on the computer. Such program code is also included in the scope of the present invention when the above embodiment is realized in cooperation with a system) or other application software.
[0152]
Further, after the supplied program code is stored in the memory of 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 function storage unit based on the instruction of the program code. A case where the CPU or the like provided performs part or all of the actual processing and the above-described embodiment is realized by the processing is also included in the scope of the present invention.
[0153]
【The invention's effect】
As described above, according to the present invention, within one unit dot pattern added to an input image, a plurality of patterns indicating important additional information are arranged adjacent to each other as shown in FIG. Therefore, additional information (for example, manufacturer ID) with high importance can be reliably decoded from the image to which these additional information is added.
[Brief description of the drawings]
FIG. 1 is a diagram showing an image processing apparatus used in this embodiment.
[Fig. 2] Layout of inspection block and reference mark
FIG. 3 is a diagram for explaining the configuration of an inspection block in detail.
FIG. 4 is a diagram showing an example of adding inspection dots in an inspection block.
FIG. 5 is a diagram for explaining a parity bit of a manufacturer 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 an aircraft number
FIG. 8 is an internal configuration diagram of the image processing unit 1000
FIG. 9 is a block diagram of an inspection dot addition processing unit.
FIG. 10 is a flowchart showing a procedure for decoding additional information from an image after adding the additional information.
FIG. 11 is a diagram showing an example of the shape of an inspection dot
FIG. 12 is a diagram showing a configuration of an inspection block in the second embodiment
FIG. 13 is a diagram showing a state where inspection dots are actually added in the second embodiment.
FIG. 14 is a diagram showing a configuration of an inspection block in the third embodiment.
FIG. 15 is a diagram showing the configuration of sub-blocks in the third embodiment.
[Explanation of symbols]
100 photosensitive drum
101 Charger
102 Transfer drum
103 Cleaner
1000 Image processing unit

Claims (19)

An adding means for periodically adding a unit dot pattern composed of a first pattern representing the manufacturer of the apparatus and a second pattern representing other additional information to the input image so that it is difficult to be recognized by human eyes;
Output means for outputting an image to which predetermined additional information is added by the adding means;
In each of the unit dot patterns, at least one second pattern is present, a plurality of the first patterns are adjacent to each other, and the plurality of first patterns represent the same content. Image processing device.   The image processing apparatus according to claim 1, wherein the plurality of first patterns existing in each of the unit dot patterns are adjacent to each other in the main scanning direction.   The image processing apparatus according to claim 1, wherein the plurality of first patterns existing in each of the unit dot patterns are adjacent to each other in the sub-scanning direction.   The image processing apparatus according to claim 1, wherein the plurality of first patterns existing in each of the unit dot patterns are adjacent to each other in a direction different from the main scanning direction and the sub-scanning direction.   The input image is a color image composed of a plurality of color planes, and the adding means adds the unit dot pattern and the reference pattern only to a part of the plurality of color planes. The image processing apparatus according to claim 1.   The image processing apparatus according to claim 1, wherein each of the dots constituting the unit dot pattern includes a plurality of pixels.   When one of the dots constituting the unit dot pattern is added by the adding means, a part of the input image is modulated to the highest density, and a part of the input image is modulated to the lowest density. The image processing apparatus according to claim 1.   When one of the dots constituting the unit dot pattern is added by the adding means, a part of the input image is density-modulated by + α, and a part of the input image is density-modulated by −α. The image processing apparatus according to claim 1, wherein:   The image processing according to claim 1, wherein the adding unit further adds a reference pattern indicating a position at which the unit dot pattern is added to the input image to each of the unit dot patterns. apparatus.   The image processing apparatus according to claim 1, wherein the adding unit adds a reference pattern indicating a position of a unit dot pattern on the input image for each unit dot pattern.   When one of the dots constituting the reference pattern is added by the adding means, a part of the input image is modulated to the highest density, and a part of the input image is modulated to the lowest density. The image processing apparatus according to claim 10.   When one of the dots constituting the reference pattern is added by the adding means, a part of the input image is density-modulated by + α, and a part of the input image is density-modulated by −α. The image processing apparatus according to claim 10.   The image processing apparatus according to claim 10, wherein the reference pattern is added to a region different from a region where the unit dot pattern exists.   The other information includes information specifying a model of the image processing apparatus, a machine number of the image processing apparatus, or information specifying a type of image processing performed by the image processing apparatus. Item 8. The image processing apparatus according to Item 1.   The image processing apparatus according to claim 8, wherein the unit dot pattern does not include a pattern having the same shape as the reference pattern.   The image processing apparatus according to claim 1, further comprising a printing unit that prints the image output from the output unit as a visible image.   The image processing apparatus according to claim 1, wherein the input image is a multi-valued image. An addition step of periodically adding a unit dot pattern composed of a first pattern representing the manufacturer of the apparatus and a second pattern representing other additional information to the input image, which is difficult to identify to the human eye;
An output step of outputting an image to which predetermined additional information is added in the adding step;
In each of the unit dot patterns, at least one second pattern is present, a plurality of the first patterns are adjacent to each other, and the plurality of first patterns represent the same content. Image processing method. An addition step of periodically adding a unit dot pattern composed of a first pattern representing the manufacturer of the apparatus and a second pattern representing other additional information to the input image, which is difficult to identify to the human eye;
An output step of outputting an image to which predetermined additional information is added in the adding step;
In each of the unit dot patterns, at least one second pattern is present, a plurality of the first patterns are adjacent to each other, and the plurality of first patterns represent the same content. Storage medium storing image processing program in a state readable from computer

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