JPH11112787A - Device for processing image, its method and storage medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily decode a pattern shape by adding a dot pattern expressing identifying information for specifying a device and its reference pattern together with additional information so as to be hardly recognized by means of human eyes to an input image, outputting them and fixing the number of dots without adding a parity check dot to the dot pattern. SOLUTION: EEPROM 901 previously stores additional information (meter ID, a function kind number and a function number, etc.) to be added to the image. Additional information is inputted to a ciphering circuit 905 when the power source of an image processor is turned-on and an image recording device to be automatically loaded to a register 902 inside the CPU 910 receives an instruction for printing a color image. Ciphered additional information is inputted to a parity check circuit 906 and a parity and a fixed bit are checked. A main scanning counter 907 transmits ON at a position where an inspection dot is added.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] 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]

2. Description of the Related Art In recent years, image recording apparatuses such as color printers and color copying machines have been able to form high-quality images by improving their performance. Under such circumstances, it is becoming possible to form an image similar to securities such as banknotes, and a technique for suppressing such an act is known.

For example, there is known an addition method for adding a dot pattern indicating a machine number of an image processing apparatus together with a color image to be printed so that it is difficult for human eyes to identify the pattern.

Usually, this dot pattern has a predetermined size, and a plurality of dots are arranged within the predetermined size. The additional information can be represented 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. Then, it is possible to specify the device that has formed these images.

Conventionally, in one device (model) manufactured by each manufacturer, the amount of information embedded in the dot pattern has a fixed length.

[0007]

However, the additional information to be added to the image differs depending on the manufacturer of the apparatus, and the amount of the additional information may be different. Further, it is necessary to set the density of dots present in the dot pattern and the size of the dot pattern in accordance with the characteristics of the device manufactured by each manufacturer.

As described above, when the method of adding a dot pattern is different for each manufacturer or each device model,
On the side that decodes an image for which image formation is supposed to be prohibited or a copy image for which copying is supposed to be prohibited, decoding methods must be prepared for the number of manufacturers and the number of device models. There is a problem that a large load is applied.

However, conventionally, there has been no method of adding a dot pattern that can correspond to the plurality of manufacturers and models.

The present invention has been made in view of the above conventional example. In a technique for adding additional information to an input image as a dot pattern, a plurality of manufacturers or devices of a plurality of models use different dot patterns on an image. It is an object of the present invention to provide a technique that can easily decipher the shape of each of these dot patterns even in the case of adding.

It is another object of the present invention to improve the image quality after adding the dot pattern as much as possible. Specifically, the quality of the image is improved by eliminating or reducing the number of parity dots required for error detection of the dot pattern and the like.

[0012]

According to the present invention, a dot pattern representing identification information for specifying an apparatus is added to an input image so as to be difficult for human eyes to identify, and a reference pattern indicating the shape or size of the dot pattern is provided. Means for adding an image to the human eye with difficulty in discrimination (corresponding to the inspection dot addition processing section 803 in the image processing section 1000 in the present embodiment)
And output means for outputting an image to which predetermined additional information has been added by the adding means (similarly, corresponding to a PWM processing section or the like in the image processing section 1000). It is characterized in that the number of dots forming the dot pattern is kept constant without addition (similarly to the addition method of FIG. 13).

In addition, a predetermined additional information may be added to an input image, and a dot pattern composed of a plurality of dots may be added to a human eye so as not to be easily recognized by the human eye, and the plurality of dots may be present. An adding means (in this embodiment, corresponding to the inspection dot adding processing section 803 in the image processing section 1000) for adding a reference pattern for specifying each dot arrangement point so as to be hardly discernible to human eyes, Output means for outputting an image to which additional information has been added (similarly, equivalent to a PWM processing unit in the image processing unit 1000)
, And control is performed so that parity dots are not arranged at all of the n parity dot arrangement points existing at the dot arrangement points (similarly, the addition method of FIG. 13 is used).

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION

(First Embodiment) In this embodiment, an image recording apparatus using color electrophotography will be 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.

In this 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 image data is input in a frame-sequential manner.

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 is possible to make it as difficult as possible for the human eye to discriminate, 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.

FIG. 1 shows the configuration of an image processing apparatus used in the following embodiments.

Reference numeral 1000 denotes an image processing unit, and R, G, B
Is sequentially input from an external device or another device inside the device, and this image is converted into multi-valued image data consisting of M, C, Y, and K, and Y of this multi-valued image data is
After adding the additional information described below only to the components,
The multi-valued image data of each color is converted into binary image data by PWM processing, and then output to the laser emitting unit 1001. The laser light emitting unit 1001 emits a laser beam L to be described later based on the input binary image data.

The photosensitive drum 100 is charged by the charger 101.
Are uniformly charged to a predetermined polarity, and a first latent image of, for example, magenta is formed on the photosensitive drum 100 by exposure with the laser beam L. Next, in this case, the required developing bias voltage is applied only to the magenta developing device Dm to develop the magenta latent image, and the photosensitive drum 100
A magenta first toner image is formed thereon.

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, positive polarity) to the toner is applied to the transfer drum. 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, and the photosensitive drum 100 is ready for the next color latent image forming and developing process.

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 cyan developing unit D is formed.
The second latent image on the photosensitive drum 100 is developed by c to form a second cyan toner image.

The cyan second toner image is
The image is transferred onto the transfer paper P in accordance with the position of the first magenta toner image previously transferred onto 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.

Similarly, third of yellow and black,
Fourth latent images are sequentially formed on the photosensitive drum 100,
Each of the toner images is sequentially developed by the developing units Dy and Db, and the third and fourth toner images of yellow and black are sequentially transferred while being aligned with the toner image previously transferred to the transfer paper P. Thus, a full-color image in which four color toner images are superimposed on each other is formed.

Next, additional information added by the image processing apparatus according to the present embodiment will be described.

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 (dot pattern) is added only to the Y plane, and FIG. 2 shows a color pattern composed of Y, M, C, and K planes. The image shown by the Y plane of the image is shown.

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, the additional information can be analyzed with respect to any area of the color image finally formed after the additional information is added. Hereinafter, this unit area 201 is called an inspection block.

The three dots 202 are referred to as reference marks, and indicate the starting position of each inspection block 201 and the directions of main scanning and sub-scanning. Further reference mark 2
02 has some information, which will be described later in detail.

In each inspection block 201, a plurality of small-area dots composed of a plurality of pixels, which will be described later, are arranged, and additional information can be represented by the arrangement method of each dot. Hereinafter, this dot is called an inspection dot.

FIG. 3 is a diagram showing the inspection block 201 of FIG. 2 in detail.

In the inspection block 201, guidelines 301 and 302 exist vertically and horizontally, and a line 301 in the vertical direction (sub-scanning direction) is defined as a sub-scanning line, and a line 302 in the horizontal direction (main scanning direction) is defined as a line. This is called a main scanning line. In this embodiment, both the main scanning line and the sub-scanning line are 0, 1,.
There are up to one.

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 at the intersection of the even-numbered main scanning line and the odd-numbered sub-scanning line.

Hereinafter, each point where the inspection dots may be arranged is designated 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
Are separated from each other by a distance 2l in the main scanning direction and the sub-scanning direction.

In the figure, the reference mark 202 is composed of three dots, and the interval (2
l), the two dots extending in the main scanning direction and the two dots extending in the sub-scanning direction each have a distance l.
Are just configured apart. Thus, regardless of the distance 2l between the adjacent dot arrangement points 303, any 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 described as being equal.
11 is 1 and each of the sub-scan lines 0 to 11 is 1 ′. In this case, the distance between two dots extending in the sub-scanning direction of the reference mark 202 is set to 1 ′. Just change it.

In the present embodiment, the reference mark 202
And the shape of each of the inspection dots is the same.

In this embodiment, the size of each inspection block 201 is 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 an adjacent inspection block 201. Can be. 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 × l.

As described above, as long as the reference mark 202 can be decoded, the shape of the inspection block 201 can be calculated.

Therefore, the number n of main scanning and sub-scanning lines in the inspection block can be calculated as n = (L−2 × l) / l + 1.

The values of L, l, and n can be freely set for each manufacturer of each device and for each model of each device. The size of the inspection block 201, the dot density, and the amount of information to be embedded are large. It is possible to make an optimal setting according to the situation. 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.

In this embodiment, the reference mark 20
The positional relationship between the three dots 2 is controlled so as not to appear between the test 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 dot arrangement status.

Next, information represented by each dot arrangement point 303 will be described.

In FIG. 3, an area 304 is a maker I
An area for indicating D (manufacturer name), and areas for main scanning lines 0 to 7 and sub-scanning lines 0 to 4 are always allocated to indicate this information.

An area 305 is a model name (printer type).
Is an area for expressing

The other area is an area for expressing a machine number unique to each printer or some information relating to an image to be added.

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.

In this embodiment, the dot arrangement point 30
The number of main scanning and sub-scanning lines in which 3 exists is both 12 lines. However, since the number of lines can be determined based on the reference mark 202 as described above, it can be set freely for each maker and model.

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. I do.

First, the inspection dot is decoded by, for example, reading a color image to which additional information is added by a scanner,
This is performed by extracting only the image of the (yellow) plane to the host computer and confirming each position of the inspection dot on the monitor of the host computer.

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.

Next, 3 which constitutes the reference mark 202
The main scanning and sub-scanning directions of the inspection block are specified based on the positional relationship between the two dots.

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.

The next reference mark 202 and the main scanning direction,
The size (L−2 × l) of the inspection block 201 is specified by measuring the distance L based on the positional relationship with the reference mark 202 adjacent in the sub-scanning direction.

Next, based on the relationship n = (L−2 × l) / l + 1, the main scanning direction and sub-scanning direction inspection blocks 20
The position of the dot arrangement point in 1 is specified.

Next, corresponding additional information is determined based on the presence or absence of a dot at the dot arrangement point.

Hereinafter, the dot arrangement point 3 on the main scanning line n
A _n0 03 from left to right, a _n1, ..., and a _n5, illustrating a case where 1 is not arranged when the test dots are arranged as 0.

First, a method of analyzing the area 304 representing the manufacturer ID will be described. The dot arrangement points existing in the area 304 are a ₀₀ , a ₀₁ , a ₀₂ , a ₀₃ , to a ₄₀ , a ₄₁ ,
is a _42, a _43, a total of 20 dots arranged points.

In the present embodiment, the dot arrangement points a ₀₀ , a ₀₁ , and
Of the four points a ₀₂ and a ₀₃ , control is performed such that only one point is 1 (dots present), and the other three points are 0 (no dots). That is, the above four points represent 2-bit information.

The same control is performed for the dot arrangement points on the main scanning lines 1, 2, and 3 in the area 304.
8 bits of information can be represented by 16 dot arrangement points in 4.

Note that a ₄₀ , which exists on the main scanning line 4,
a ₄₁ , a ₄₂ and a ₄₃ are points for parity check.

FIG. 5 shows the information (manufacturer I) in the area 304.
FIG. 9 is a diagram for explaining a parity check method for D). a _{00 to} a ₄₃ are arranged as shown in the figure, and a ₄₀ , a ₄₁ , a
It is confirmed that ₄₂ and a ₄₃ are 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.

On the other hand, if no error occurs in the above parity check, the following two values are set according to the values of a ₀₀ , a ₀₁ , a ₀₂ , and a _03.
Convert to a bit value.

[0061] _{(a 00 a 01 a 02 a} 03) (0 0 0 1) → 00 (0 0 1 0) → 01 (0 1 0 0) → 10 (1 0 0 0) → 11

Subsequently, a ₁₀ -a ₁₃ , a ₂₀ -a ₂₃ , a _30-
in the order of a _33, Yuki converted to 2-bit values in a manner similar to that described above, by arranging the 2-bit value obtained from left to right, it is possible to obtain the 8-bit manufacturer ID.

In the case of the arrangement of the test dots shown in FIG. 4 of the present embodiment, maker ID = 0, 1, 0, 1, 1, 1, 0, 0 (binary number) = 92 (decimal number) Becomes Since the maker ID has a unique number for each maker, it can be specified that the copying machine and the printer manufactured by the maker of No. 92 have formed the image.

Next, a method of analyzing the area 305 representing the model number will be described. Note that the dot placement points present in the region 305 is _{a 04, a 05 ~a 44,} a 45, a total of 10 dots arranged points.

The two dot arrangement points a ₀₄ and a ₀₅ on the main scanning line 0 in the area 305 are controlled so that one of them is 1 (dots present) and the other is 0 (no dots). Is done. Therefore, 1-bit information can be represented by the presence or absence of the dots a ₀₄ and a ₀₅ .

The points on the main scanning lines 1, 2, and 3 are similarly controlled. Therefore, the above eight points a ₀₄ , a _{05 to} a ₃₄ , and a ₃₅ represent 4-bit information.

Further, a ₄₄ and a ₄₅ on the main scanning line 4 are parity check points.

FIG. 6 shows information (model number) in area 305.
FIG. 4 is a diagram for explaining a method of parity check for. a _{04 to} a ₄₅ are arranged as shown in the figure, and it is confirmed that a ₄₄ and a ₄₅ are 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.

On the other hand, if no error occurs in the parity check, the parity check is converted to a 1-bit value according to the values of a ₀₄ and a ₀₅ as follows.

[0070] _{(a 04 a 05) (0} 1) → 0 (1 0) → 1

Subsequently, a _{14 to} a ₁₅ , a _{24 to} a ₂₅ , a ₃₄ to
in the order of a _35, then converted as described above, by arranging 1-bit values obtained from the left, the 4-bit model number.

In the case of the arrangement state of the test dots shown in FIG. 4 of the present embodiment, the model number = 1, 0, 0, 1 (binary number) = 9 (decimal number).

Next, a description will be given of a method of analyzing an area representing a machine number and other information.

Out of the six points a _{50 to} a ₅₅ on the main scanning line 5, only two points are controlled to be 1 (with dots), and the other four points are controlled to be 0 (no dots). . Therefore, 15 kinds of information can be shown by the above 6 points.

Similar control is performed for points on the main scanning lines 6 to 10. Thus, by using the up main scanning lines 5-10, it would represent information types 15 ^6.

Note that a _{110 to} a ₁₁₅ on the main scanning line 11
Is a point for parity check.

FIG. 7 is a diagram for explaining a parity check method for information (machine number and other information) in this area. a _{50 to} a ₁₀₅ are arranged as shown in the figure.
It is confirmed that _{110 to} a ₁₁₅ become 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.

On the other hand, if no error occurs in the above parity check, the data is converted into a hexadecimal number as follows according to the values of a _{50 to} a ₅₅ .

[0079] _{(a 50 a 51 a 52 a} 53 a 54 a 55) (0 0 0 0 1 1) → 0 (0 0 0 1 0 1) → 1 (0 0 0 1 1 0) → 2 (0 0 1001) → 3 (001101) → 4 (010110) → 5 (010001) → 7 (0101) → 7 (0101) 0 10 0) → 8 (0 1 1 1 0 0 0) → 9 (1 0 0 0 0 1) → A (1 0 0 0 0 1 0) → B (1 0 0 0 0 0 1) → C (1 0 0 (1000) → D (110 000) → E

Subsequently, a _{60 to} a ₆₅ , a _{70 to} a ₇₅ , a ₈₀ to
a ₈₅ , a _{90 to} a ₉₅ , and a _{100 to} a ₁₀₅ are converted in the same manner as described above, and the obtained hexadecimal numbers are arranged in order from the left. Information. Note that the manufacturer of this device is the first digit of 15
The base number indicates the image processing mode, and the machine number is
If this is expressed by a 15-digit decimal number, FIG.
In the case of the arrangement state of the inspection dots shown in (1), image processing mode = 0 (decimal number) = 0 (decimal number) body number = 0, E, 7, 8, 1 (decimal number) = 4894
6 (decimal).

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 by the manufacturer, it is possible to add sub-scan lines 12, 13 and the like in order to increase the dot arrangement points. It can be expressed in base numbers.

In this embodiment, the inspection block 20
In order to prevent the dot density in 1 from being extremely increased or decreased, the number of test dots (dots present: 1) existing on each main scanning line in each area in the test block 201 is specified. That is, the adjustment is performed so that the number of inspection dots existing on each main scanning line in the inspection block 201 is 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, also in this case, 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 the lines on which the check dots for parity check are arranged, and the parity check method is used. Is also defined by the above method.

FIG. 8 is a schematic diagram of the inside of the image processing unit 1000 of FIG.

In the figure, reference numeral 801 denotes an image input unit for inputting RGB multi-valued color image data from an external device such as a host computer or another device inside the device in a frame-sequential manner.

Reference numeral 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 it to the subsequent stage in a frame sequential manner. An image processing unit.

An inspection dot addition processing unit 803 adds the above-described additional information (inspection dots) only to the Y component in 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.

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 above-described laser emitting unit 1001.

FIG. 9 shows the inspection dot addition processing section 80 shown in FIG.
3 is an internal configuration diagram of FIG.

The EEPROM 901 stores additional information (a maker ID, a model number, a machine number, etc.) to be added to an image in advance. 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.

Note that, in addition to the above-mentioned additional information, the register 902 also stores a fixed bit in which a fixed value is entered and a parity bit for parity check.

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.

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 remodeled, and control is performed to forcibly stop the printing operation.

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 check dot is to be added according to the code loaded from the parity check 906.

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.

The inspection dot generation circuit 909 reads out inspection dot shape parameters stored in the ROM 903 in the CPU. The inspection dot generation circuit 909 further includes a permission signal that is turned on when a Y (yellow) plane is input to the inspection dot addition circuit 904, and a main scanning counter 90.
7. By inputting a permission signal that turns on both the sub-scanning counters 908, the position to which the inspection dot is added is determined, and an 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 other image positions of the yellow plane and the image positions of the M, C, and K planes are turned off and output.

The test dot adding circuit 904 turns off the additional signal for the input multi-valued image data (yellow).
If this is the case, the multi-valued image data is output as it is, and if the additional signal is ON, it is converted to the pixel value at the time when the inspection dot was added and then output. Thereby, additional information (reference mark and each inspection dot in the inspection block) as shown in FIG.
Can be added.

Note that the CPU 910 in FIG. 9 is prepared to control only the inside of the inspection dot adding circuit 904, but may be used to control the entire image processing unit 1000.
U may be shared. Also, the EEPROM 90
For example, a common memory that can store other information related to the image processing unit 1000 may also be used.

Next, the operation procedure for decoding the additional information will be described with reference to the flowchart of FIG.

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.

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 forming 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).

Next, in the main scanning direction and the sub-scanning direction,
The reference marks 202 adjacent to each other 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 the dot arrangement points are specified (step S5).

Next, the area 30 representing the maker ID described above
4 (step S6), the parity check of FIG. 5 described above is performed (step S7), and 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).

Next, the 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 (step S9). Start over. on the other hand,
If no error occurs, a model number is obtained (step S1).
1).

Next, the area indicating the machine number and other information is inspected (step S12), and the area shown in FIG.
Is checked (step S13), and if an error occurs, the above area inspection (step S12) is repeated. On the other hand, if no error occurs, the device number and other information are obtained (step S14).

With the above steps, the additional information can be decoded.

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. Therefore, the decoding is performed in a series of steps as shown in FIG. I was able to. However, the main scanning line in the inspection block 201 (main scanning line 5 in FIG. 4)
In the case where the number of test dots arranged on each of the manufacturers differs from manufacturer to manufacturer, decoding cannot be performed in the above series of steps (additional information is 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.

In this embodiment, the reference mark 202
The distance 21 between the dot arrangement points 303 is represented based on the distance l between the three dots in the reference mark 202.
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 by analyzing the arrangement of the three dots. 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 using the distance of the three dots in the main scanning direction and the sub-scanning direction as 1.

FIG. 11 shows an example of the shape of the inspection dot arranged at the dot arrangement point 303. Each test dot is 4 × 4
It is composed of pixels.

The original image (only the yellow plane) is placed at the center of each inspection dot in FIG.
There is an area converted to F, with a minimum density of 0 at both ends.
There is a region converted to 0. 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.

The original image (only the yellow plane) is added to the center of each test dot in FIG.
There is a region whose density has been converted by only .alpha., And a region whose density has been converted by -.alpha. In the case of (b), the density difference between the center and both ends is not as large as (a).
Although there is a problem that the recognition probability of the inspection dot is reduced, there is an advantage that the density is substantially preserved in the original image (yellow plane). Therefore, even if only the yellow plane is viewed, deterioration of the image quality is reduced.

According to the above-described 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 about the addition method is also added to the input image that is difficult for the human eye to identify. On the decryption side, the additional information can be reliably decrypted.

In particular, when it is necessary for each device of a plurality of manufacturers to decode the additional information from any image to which the additional information is added, if the shape of the inspection block 201 in FIG. Since the information which can specify the shape 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.

(Second Embodiment) In the above embodiment, the arrangement points of the parity check check dots (the intersections of the main scanning line 4 and the sub-scanning lines 1, 3, 5, and 7 in FIG. 3) are set. There are cases where two to four test dots are added side by side. In this case, the existence of these inspection dots may be conspicuous.

In this embodiment, the arrangement of the test dots is controlled so that the density of the test dots in the test block is not increased as much as possible. Note that the configuration of the device is the same as that of the first embodiment, and a description thereof will be omitted.

FIGS. 12 and 13 show examples of the arrangement of the test dots according to the present embodiment.

In this embodiment, as shown in FIG. 12, the arrangement points of the parity check check dots are not provided. The maker ID area 304 includes main scanning lines 0 to 3 and sub-scanning lines 0 to 7. In the area 304, there are 16 dot arrangement points. On the main scanning line n a _n0 ~a _n3 (n =
Only one of the four points (0, 1, 2, 3) is 1
(With dots) and the other three points are controlled to be 0 (no dots).

Further, in the sub-scanning direction, a _{0n to} a
_Of the four points of _3n (n = 0, 1, 2, 3), the number of dots that become 1 (there is a dot) is controlled to be an even number.

By controlling the dot arrangement method as described above, the maker ID area 304 can represent 40 types of information, and it is possible to identify up to 40 manufacturers from the dots added to the area 304. It is.

At the time of decoding, a _{0n to} a _3n (n = 0, 1, 2,
Check that the sum of 3) is even. This is exactly the same operation as the parity check in the above embodiment.

Further, assuming that the error rate of the inspection dot determination at the time of decoding is p, the erroneous detection rate of the manufacturer ID ≦ about 18 × p ⁴ × (1-p)
¹² , which indicates that the probability of erroneous detection is very low.

Next, control of the arrangement of dots in the area 305 representing the model number will be described. The dot arrangement points existing in the area 305 are a ₀₄ , a _{05 to} a ₃₄ , and a _35, that is, a total of eight dots.

One of the two dot arrangement points _an4 and _an5 (n = 0, 1, 2, 3) on the main scanning line n in the area 305 becomes 1 (dots exist), and the other Is controlled to be 0 (no dot). Further, of the four points a _{0n to} a _3n (n = 4, 5), 1
The number of dots (with dots) is controlled to be an even number.

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. When decoding, a _0n ~
Confirm that the sum of a _3n (n = 4, 5) is an even number.

Further, the erroneous detection rate of the model number is: erroneous detection rate of the model number = approximately 6 × p ⁴ × (1-p) ⁴ .

Next, the dot arrangement control of the area indicating the machine number and other information will be described.

Six dot arrangement points a on the main scanning line n
_{Of n0 to an5} (n = 4 to 11), only two points are controlled to be 1 (with dots), and the other four points are controlled to be 0 (no dots). Also, in the sub-scanning direction, a _{n4 to} a
_n11 (n = 0 to 5) of the eight points, 1 (with dot)
Is controlled so as to be an even number of dots.

By controlling the dot arrangement method as described above, information necessary for a maker can be represented in this area.

[0128] At the time decryption to verify that the sum of _{a n4 ~a n11 (n = 0~5} ) even.

The erroneous detection rate in this area is as follows: erroneous detection rate ≦ approximately 224 × p ⁴ × (1-p) ⁴⁴

According to the above embodiment, the maker I
Regardless of the contents such as D, model number, and number unique to each device,
Since the density at which the test dots are added in the test block can be kept constant, the test dots do not become conspicuous, and the probability of erroneous detection during decoding can be reduced.

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. It is only necessary to control the dot arrangement method so as to reduce the number of dots as much as possible.

That is, regarding the area 304, a point a _{5n at} which a dot for parity check should be arranged as shown in FIG.
(N = 0 to 3) while maintaining the dot arrangement such that no dot for parity check is added to all of the four arrangement points (an arrangement in which dots are added to 0 to 3 of _a5n ).
May be applied to a _{00 to} a ₀₄ , a _{10 to} a ₁₄ , a _{20 to} a ₂₄ , and a _{30 to} a ₃₄ . By doing so, at least the points a _5n (n
= 0 to 3), there is no case where four dots are arranged, so that good image quality can be maintained.

Similarly, control is performed so that two or more or three or more points are not added to the points a _5n (n = 0 to 3) where the dots for parity check are to be arranged (0 to 1 or 0 to 2 for a _5n ).
It is also possible to control the number of dots to be added. In the second embodiment, the point a _5n (n = 0 to
3) One or more since the added non controlled to (a _5n zero dots was controlled), such as is added to, the constellation points a _5n
(N = 0 to 3) itself is eliminated.

The control of the above dot arrangement method is shown in FIG.
The data itself stored in the EEPROM 901 may be limited in advance, but the EEPROM 901 is designed so that the CPU 910 executes only the above-described dot arrangement.
The data stored in M901 may be read in a different interpretation method. Further, it may be executed at the time of encryption in the encryption circuit 905.

(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.), one device (for example, a copying machine) , A facsimile machine).

Further, the present invention is not limited to only the apparatus and method for realizing the above-described embodiment, but includes a computer (CPU or MP) in the above-described system or apparatus.
U), a program code of software for realizing the above-described embodiment is supplied, and the computer of the system or the apparatus operates the various devices according to the program code to realize the above-described embodiment. It is included in the category of the present invention.

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 the computer, specifically, A storage medium storing the above program code is included in the scope of the present invention.

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 and the like can be used.

In addition to the case where the computer controls the various devices in accordance with only the supplied program code to realize the functions of the above-described embodiment, the program code operates on the computer. Such a program code is included in the scope of the present invention even when the above-described embodiment is realized in cooperation with an OS (Operating System) or other application software.

Further, after the supplied program code is stored in a memory provided in a function expansion board of a computer or a function expansion unit connected to the computer, the function expansion board or function is stored based on the instruction of the program code. The case where the CPU or the like provided in the storage unit 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.

[0141]

As described above, according to the present invention, in a technique for adding additional information as a dot pattern to an input image, different dot patterns are added to an image by a plurality of manufacturers or a plurality of types of apparatuses. In such a case, the shape of each dot pattern can be easily decoded.

Since the number of dots constituting the dot pattern to be added is controlled, it is possible to eliminate or reduce the number of dots for parity check. Image quality can be improved.

[Brief description of the drawings]

FIG. 1 is a diagram showing an image processing apparatus used in the present embodiment.

FIG. 2 is an arrangement 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 showing 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.

FIG. 12 is a diagram showing a configuration of an inspection block according to the second embodiment.

FIG. 13 is a diagram showing a state where test dots are actually added in the second embodiment.

[Explanation of symbols]

 REFERENCE SIGNS LIST 100 photosensitive drum 101 charger 102 transfer drum 103 cleaner 1000 image processing unit

Claims (26)

[Claims] An input image is provided with a dot pattern representing identification information for identifying a device, which is difficult to identify to a human eye, and a reference pattern indicating the shape or size of the dot pattern is input to a human eye. And an output unit for outputting an image to which predetermined additional information has been added by the adding unit, wherein the dot pattern is added without adding a parity check dot to the dot pattern. An image processing apparatus characterized in that the number of dots constituting the image data is fixed. 2. The image processing apparatus according to claim 1, wherein the dot pattern is capable of detecting an error based on an arrangement state of dots forming the dot pattern. 3. The input image is a color image composed of a plurality of color planes, and the adding means adds the dot pattern and the reference pattern only to some of the plurality of color planes. The image processing apparatus according to claim 1, wherein: 4. The image processing apparatus according to claim 1, wherein each of the dots forming the dot pattern includes a plurality of pixels. 5. A part of the input image is modulated to a maximum density and a part of the input image is modulated to a minimum density by adding one of the dots constituting the dot pattern by the adding means. 2. The method according to claim 1, wherein
An image processing apparatus according to claim 1. 6. A part of the input image is density-modulated by + α, and a part of the input image is density-modulated by −α by adding one of the dots constituting the dot pattern by the adding means. The image processing apparatus according to claim 1, wherein the processing is performed. 7. The image processing apparatus according to claim 1, wherein the reference pattern is a pattern composed of a plurality of dots. 8. The image processing apparatus according to claim 1, wherein each of the dots forming the reference pattern includes a plurality of pixels. 9. One of the dots constituting the reference pattern
9. The image processing apparatus according to claim 8, wherein a part of the input image is modulated to a maximum density and a part of the input image is modulated to a minimum density by adding one to the other. apparatus. 10. A part of the input image is density-modulated by + α, and a part of the input image is density-modulated by −α by adding one of the dots constituting the reference pattern by the adding means. The image processing apparatus according to claim 8, wherein the image processing is performed. 11. The image processing apparatus according to claim 1, wherein the dot pattern is periodically added to the input image. 12. The image processing apparatus according to claim 1, wherein the reference pattern is periodically added to the input image. 13. The image processing apparatus according to claim 1, wherein the reference pattern can specify a position where the dot pattern exists. 14. The image processing apparatus according to claim 1, wherein the reference pattern is added to an area different from an area where the dot pattern exists. 15. The identification information for specifying the apparatus, information for specifying a manufacturer of the image processing apparatus, information for specifying a model of the image processing apparatus, or a machine number of the image processing apparatus. The image processing apparatus according to claim 1, further comprising: 16. The image processing apparatus according to claim 1, wherein the dot pattern does not include a pattern having the same shape as the reference pattern. 17. The image processing apparatus according to claim 1, further comprising printing means for printing an image output from said output means as a visible image. 18. The image processing apparatus according to claim 1, wherein the input image is a multi-value image. 19. An input image, wherein a dot pattern representing identification information for identifying a device is added to a human eye so as not to be easily identified, and a reference pattern indicating the shape or size of the dot pattern is added to the human eye. And an output step of outputting an image to which predetermined additional information has been added in the adding step, without adding a dot for parity check to the dot pattern. An image processing method characterized by keeping the number of dots forming a pattern constant. 20. A method of adding a dot pattern representing identification information for specifying a device to an input image, which is difficult to recognize by a human eye, and adding a reference pattern indicating the shape or size of the dot pattern to a human eye. And an output step of outputting an image to which predetermined additional information has been added in the adding step, without adding a dot for parity check to the dot pattern. A storage medium storing an image processing program, wherein the number of dots forming a pattern is fixed, in a state readable by a computer. 21. A method in which predetermined additional information is added to an input image, a dot pattern composed of a plurality of dots is added to the input image so that it is difficult for human eyes to recognize, and the plurality of dots may be present. An addition unit that adds a reference pattern that specifies each dot arrangement point so that it is difficult for a human eye to identify; and an output unit that outputs an image to which predetermined additional information is added by the addition unit. An image processing apparatus for controlling a parity dot not to be arranged at all of the n parity dot arrangement points existing in the image processing apparatus. 22. The apparatus according to claim 2, wherein the reference pattern indicates a distance between adjacent dot arrangement points.
2. The image processing device according to 1. 23. The image processing apparatus according to claim 21, wherein error detection can be performed on the dot pattern based on an arrangement state of dots forming the dot pattern. 24. The image processing apparatus according to claim 23, wherein the control is performed such that M or more parity dots where N ≧ M of n parity dot arrangement points existing at the dot arrangement points are not arranged. 22. The image processing device according to 21. 25. A method in which predetermined additional information is added to an input image, a dot pattern composed of a plurality of dots is added to the input image so as to be difficult for human eyes to recognize, and the plurality of dots may be present. An adding step of adding a reference pattern specifying each dot arrangement point so that it is difficult for a human eye to recognize; and an output step of outputting an image to which predetermined additional information is added in the adding step, Wherein the parity dots are controlled so as not to be arranged at all of the n parity dot arrangement points existing in the image processing apparatus. 26. A method in which predetermined additional information is added to an input image, and a dot pattern composed of a plurality of dots is added to the input image so as to be difficult for human eyes to recognize, and the plurality of dots may be present. An adding step of adding a reference pattern specifying each dot arrangement point so that it is difficult for a human eye to recognize; and an output step of outputting an image to which predetermined additional information is added in the adding step, And a computer-readable storage medium storing an image processing program for controlling parity dots not to be arranged at all of the n parity dot arrangement points existing in the computer.