JP2001103284A - Image processing device and image processing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image processing device and an image processing method by which attached information can surely be read through separation from a recorded image on which the additional information is multiplexed even by using, e.g. a spread type image reader with a low resolution while minimizing degradation in the image quality even when the attached information is multiplexed on the image information. SOLUTION: In the case of multiplexing the attached information on the image information, the attached information is multiplexed by taking the resolution of an image output device and an image reader into account so as to use a minimum set of pixels that can be read by the image reader.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image processing apparatus and an image processing method, and more particularly to an image processing apparatus and image processing for multiplexing additional information with image information to output an image and separating the additional information from the output image. About the method.

[0002]

2. Description of the Related Art Multiplexing of heterogeneous information to image information is not only a method of protecting copyrights, preventing forgery of bills and securities, protecting confidential information, but also various methods of transmitting characters and voices. A method has been proposed. For example, Journal of the Institute of Image Electronics Engineers of Japan 1998
Year, Vol. 27, No. 5, pp 483, "Digital Watermarking Technology and Its Evaluation Items" introduces various digital watermarking technologies.

A method of multiplexing different types of information into image information is roughly classified into a method of embedding in the frequency domain and a method of embedding in the real space area of the image. Embedding in the frequency space mainly involves converting the image data from the real space domain to the frequency domain using a means such as fast Fourier transform (FFT), and then adding additional information using frequency components and phase components. This is realized by multiplexing. On the other hand, embedding in the real space area is realized using the value of the least significant bit (LSB) of each pixel of the image data and a quantization error generated when the image data is quantized.

A technique for multiplexing different types of information in an image processing apparatus that performs image expression using pseudo-gradation expression includes, for example, an error diffusion method as disclosed in Japanese Patent Application No. 11-90071. Multiplexing of heterogeneous information while suppressing image quality degradation by artificially creating a combination of quantization values that cannot occur while preserving the image density during pseudo gradation processing using There is a way.

[0005]

However, the above conventional example has the following problems.

(1) When information is multiplexed with respect to frequency components of image data, pixel values of full-color image data, and the like, in a recording apparatus that records an image using pseudo gradation expression, multiplexing is performed after recording. For example, there is no guarantee that the code representing the converted information is stored on a recording medium such as a recording sheet.

(2) A recent recording apparatus has a high resolution in order to realize high quality of an image. In order to detect a code embedded in the image, reading by an image reading apparatus such as a scanner is required. The resolution must be high. In order to reliably read the code, the resolution of the reading-side device is required to be at least twice the resolution of the recording side according to the sampling theorem. However, compared to a recording device such as an ink jet printer, the reading resolution of an image reading device such as a popular type scanner is only equal to or lower than the resolution. Therefore, if multiplexing of heterogeneous information into image information is performed without considering the resolution of the reading apparatus, an expensive special scanner with high resolution is required to reliably separate the heterogeneous information from the recorded image. Is not practical.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem. Even if additional information is multiplexed with image information, the deterioration of image quality is minimized, and the additional information is multiplexed. It is an object of the present invention to provide an image processing apparatus and an image processing method capable of reliably separating and reading additional information from a recorded image even if a popular low-resolution image reading apparatus is used.

[0009]

In order to achieve the above object, an image processing apparatus according to the present invention has the following arrangement.

That is, an image processing apparatus for multiplexing additional information with image information, comprising: a first input unit for inputting the image information; a second input unit for inputting the additional information; Considering the resolution of the image output device that outputs the image as the image output device and the resolution of the image reading device that reads the image output from the image output device, the additional information is represented by a set of pixels that can be read by the image reading device. A multiplexing unit that multiplexes the additional information with the image information to perform pseudo-gradation processing, and an output unit that outputs image data subjected to pseudo-gradation processing by the quantization unit. A processing device is provided.

Here, the pseudo gradation processing may be performed according to an error diffusion method or a dither method.

A set of pixels representing the additional information generated by the quantization means is composed of continuous pixels,
The continuous pixel has a first quantization value, and the size of the continuous pixel having the first quantization value is preferably determined in consideration of the resolution of the image reading device. Then, the quantization means is adjacent to a set of continuous pixels having the first quantization value, and stores the average density of the image information in a peripheral area of the pixel where the additional information is multiplexed. A second compensating for the density represented by the set of consecutive pixels having a quantization value of 1
It is preferable to generate a set of continuous pixels having a quantization value of

Further, the additional information multiplexed in the image information may be represented by a combination of a set of continuous pixels having a first quantization value and a set of continuous pixels having a second quantization value.

It is preferable that the additional information is added to one of a plurality of color components constituting the image information. It is more preferable to check for each component, and select a color component that is difficult to be visually recognized from a plurality of color components as a color component of the image information in which the additional information is multiplexed, based on the average density of the neighboring pixels.

Further, when the second input means inputs a plurality of pieces of additional information, the additional information is classified so as to multiplex different color components of the image information for each of the plurality of pieces of additional information. And good.

According to still another aspect of the present invention, there is provided an image processing apparatus for reading an image in which additional information is multiplexed and separating the additional information, wherein: a reading means for reading the image; Detecting means for detecting the converted position, and separating means for specifying the additional information multiplexing position of the image based on the detection result by the detecting means and separating the additional information from the specified position. An image processing apparatus is provided.

Here, the detecting means may read a predetermined dot pattern recorded in a predetermined area of the image to detect a multiplexing position of the additional information.
Alternatively, a position determined according to a predetermined image format may be regarded as a position where the additional information is multiplexed.

The reading means is preferably a scanner.

On the other hand, the separating means measures the difference between the average density value near the specified additional information multiplexing position and the maximum value and the minimum value of the local average pixel value, and calculates the difference between the measured average density value and the average density value. Based on the difference, the value of the code representing the additional information may be extracted. In this case, one of a plurality of thresholds is further selected based on the average density value, and the selected threshold and the difference are determined. It is preferable to extract the value of the code by comparison.

According to still another aspect of the present invention, there is provided an image processing method for multiplexing additional information with image information and separating the additional information from an image in which the additional information is multiplexed, wherein the image information is input. A first input step of inputting the additional information, a resolution of an image output device that outputs the image information as an image, and a resolution of an image reading device that reads an image output from the image output device. In consideration of, a quantization step of multiplexing the additional information with the image information so that the additional information is represented by a set of pixels readable by the image reading device, and performing a pseudo gradation process,
An output step of forming an image based on the pseudo gradation processed image data to output an image, a reading step of reading the image, and a detection step of detecting a position where additional information is multiplexed in the image. A multiplexing position of the image based on the detection result in the detecting step, and separating the additional information from the specified position. .

According to still another aspect of the present invention, a program for multiplexing additional information with image information and / or executing an image processing for separating the additional information from an image in which the additional information is multiplexed is stored. Computer-readable memory, wherein the program executes a first input process of inputting the image information, a code executes a second input process of inputting the additional information, and the image information as an image. Considering the resolution of the image output device to output and the resolution of the image reading device that reads the image output from the image output device, the additional information is represented by a set of pixels readable by the image reading device. A code for multiplexing the additional information with the image information and executing a process of performing pseudo gradation processing, and an image based on the pseudo gradation processed image data; A code for executing a process of outputting an image by performing a process, a code of executing a reading process of reading the image, a code of executing a detection process of detecting a position where the additional information is multiplexed in the image, A code for specifying a position where the additional information is multiplexed on the image based on a detection result in the detection process, and executing a separation process for separating the additional information from the specified position. Is provided.

[0022]

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

<First Embodiment> FIG. 1 is a block diagram showing the configuration of an image processing apparatus as a typical embodiment of the present invention. As shown in FIG. 1, this apparatus includes a host computer (hereinafter referred to as a host) 10 for processing image information.
0, a scanner 110 that reads an image document to generate image information, a communication interface (I / F) 120 that receives image information via a communication line, a LAN interface 130 that receives image information via a LAN, LCD, PDP, FED or C to display as image
It includes a display 140 such as an RT, a printer 150 for outputting image information as an image to a recording medium such as recording paper, a keyboard (KB) 160 for performing various man-machine operations required for image processing, and a mouse 170.

The host 100 includes a CPU for performing image processing and communication control processing, and an RO for storing a control program and the like.
M, a RAM for storing image information and as a work area for image processing, a hard disk for storing large-capacity data, a magneto-optical disk, and an interface for connecting various peripheral devices.

The data received by the communication interface (I / F) 120 may be facsimile data or digital image information input via the Internet.

The printer 150 basically comprises a printer controller and a printer engine serving as an interface with the host 100. The printer engine may be a printer engine according to an ink jet system, a printer engine according to an electrophotographic system, or
An engine according to another recording method may be used.

The image processing apparatus having the above configuration can be configured as a single copying machine by removing a communication interface and a LAN interface from the above configuration, and integrating a display, a keyboard, a mouse, and the like as an operation panel. If a LAN interface is removed, a display, a keyboard, a mouse, and the like are combined as an operation panel, and if the communication interface is an interface dedicated to facsimile, it can be configured as a single facsimile, there are various modes as specific devices. Further, if a personal computer is adopted as a host and the above devices are connected as peripheral devices, an image processing system can be configured.

It is efficient that the image processing in the following description is mainly realized as printer driver software in a host that creates image information to be output to a printer engine. Alternatively, it may be realized by hardware incorporated in software or the like.

FIG. 2 shows a multiplexer for multiplexing additional information into image information and recording an image using the system shown in FIG. 1, and a demultiplexer for reading an image in which additional information is multiplexed and separating the additional information. FIG. 3 is a block diagram showing the configuration of FIG. In FIG. 2, (a) shows the configuration of the multiplexer.
(B) shows the configuration of the separation device.

Considering the correspondence with FIG. 1, the multiplexing device comprises a host 100, a display 140, a keyboard 170 and a mouse 170, and the separating device comprises a host 100, a scanner 110, a display 140 and a keyboard 170.
And a mouse 170. However, it goes without saying that the multiplexing device and the demultiplexing device may be separate devices that are completely separated from each other.

In FIG. 2A, reference numeral 101 denotes the quantization of the target pixel based on the image information around the target pixel, the sign of the additional information, the resolution of the target scanner device, and the condition of the position where the sign is added. A quantization condition determination unit 102 for determining a quantization condition used in performing the processing converts the input image information into a quantization level smaller than the number of input gradations by pseudo gradation processing, and Is a quantization unit that expresses the gradation in terms of the area by the quantization value of.

Reference numeral 200 denotes an input terminal for inputting multi-gradation image information; 201, an input terminal for additional information to be multiplexed in the image information; 202, an input terminal for inputting a reading resolution of a target scanner; Is an input terminal for inputting the resolution of the printer 150, and 204 is an input terminal for inputting a condition for determining a code addition position when adding a code in an image. The input terminal 204 of the multiplexing device is not a literal input terminal but has various modes such as an input source for inputting information from the host to the user of the device, and an input source for automatically inputting information by software performing multiplexing processing. .

The multi-tone image information input from the input terminal 200 may be input via the Internet or a LAN, may be input via the scanner 110, or may be input from the host 100. May be generated.

Next, in FIG. 2B, reference numeral 103 denotes a sign-added color extracting unit for extracting a color component to which a sign is added from the image information obtained by the scanner 110; A code addition area detection unit that detects a code addition area from the code addition color component of the image information obtained in step 1 and the code addition position condition, and 105 measures an average pixel value in the code addition area and determines a threshold value corresponding to the average pixel value. The threshold selector 106 selects local density at an arbitrary location in the sign addition area, detects the maximum value and the minimum value, calculates the difference between the maximum value and the minimum value, and calculates the pixel value A pixel value distribution state detection unit 107 for detecting the distribution state of the threshold value and the pixel value distribution state detection unit 106 selected by the threshold value selection unit 105
Is a sign determination unit that compares the difference between the local average pixel values calculated in step (1) and determines the sign.

An output terminal 205 outputs the additional information separated by the separation device.

In the system having the above-described configuration, the multiplexing device connects the input terminal 204 to, for example, the top line or several lines from the top of the recorded image output from the printer 150.
While the code addition position condition input from is recorded in the form of a predetermined dot pattern, the separation device reads the image recorded by the multiplexing device when the image is recorded at the top line or several lines from the top. First, the recorded dot pattern is read to extract the code addition position condition.

However, if both the multiplexing device and the demultiplexing device handle an image having a predetermined format, and if the software that handles the format is executed in each device, the code addition position condition is added to the software in advance. If set, the recording and reading of the dot pattern as described above need not be performed.

If the code addition position condition set by the multiplexing device can be known on the demultiplexing device side, the condition may be input by the device user at the demultiplexing device host. If two devices are connected by a network, the condition may be input via the network.

As described above, the sign-added position condition input terminal 204 on the side of the separating device is not a literal input terminal but has various modes.

Next, a code addition process (multiplexing of additional information) performed by the multiplexer having the configuration shown in FIG. 2A when the quantization value is binary and the image recording resolution and reading resolution are the same. Will be described with reference to the flowchart shown in FIG.

Here, it is assumed that the color component to which the sign is added is a color which is most difficult to be visually recognized. For example, four colors of cyan (C), magenta (M), yellow (Y), and black (Bk) are selected. In the case of a printer that performs recording using one ink, the addition is made to the Y component that is most difficult to visually recognize. The sign is added, for example, in Japanese Patent Application No. 11-90.
As proposed in Japanese Patent Application No. 071, this can be realized by changing the quantization result by changing the quantization condition in the error diffusion method. Therefore, also in this embodiment, it is assumed that the sign is added to the image information by changing the quantization condition at the time of the pseudo gradation processing, and the size of the image information is m × n pixels.

First, in step s200, variables (i) and (j) for counting addresses in the vertical direction (i (row) direction) and the horizontal direction (j (column) direction) of the image are respectively set as follows.
Initialize to “0”. Next, in step s201, it is checked whether or not the address value indicated by the vertical address variable (i) is a line to which a sign is to be added.
In 02, it is checked whether or not the address value indicated by the horizontal address variable (j) is a column to which a sign is added.

If it is determined in steps s201 and s202 that the value indicated by the address variable is the sign addition position, the process proceeds to step s203, where the value (n) of the sign counter is calculated from the coordinate value of the pixel of interest. . Here, the code counter (n) is a code number counter for storing processing contents for codes generated over a plurality of rows.

In step s204, it is checked whether the n-th code is created for the first time or is being created. If it is determined that the code is a code to be created for the first time, the process proceeds to step s205, and the quantization condition is derived with reference to the image information and the code to be added. Then, in step s206, the quantization condition at the time of creating the n-th code derived in step s205 is stored, and then the process proceeds to step s207. On the other hand, if it is determined in step s204 that the code is being created, the process proceeds to step s208 to acquire the stored quantization condition of the code number (n), and then the process proceeds to step s207. Proceed to.

If it is determined in step s201 or s202 that the value of the address variable does not indicate the place where the sign is to be added, the process proceeds to step s209, and the normal quantization without sign addition is performed. After acquiring the condition, the process proceeds to step s207.

In step s207, pseudo gradation processing is performed on the image information. In particular, details of the pseudo-gradation processing in the code addition area will be described later with reference to FIG.

In step s210, the count value of the address variable (j) in the column direction is incremented by "1". In step s211, it is checked whether the processing in the column direction has been completed. Here, for the same value of the address variable (i), if the processing in the column direction has not been completed, the processing proceeds to step s20.
2 and the above-described processing is repeated. On the other hand, if the process has been completed, the process proceeds to step s212, the address variable (j) in the column direction is initialized to “0”, and in step s213, the address variable (i) in the row direction is reset. The count value is incremented by "+1".

Further, in step s214, it is checked whether or not the processing has been completed for all the rows. If it is not determined that the processing has been completed, the processing returns to step s201, and the above processing is repeated. On the other hand, if it is determined that the process has been completed, the process proceeds to step s215, and the image information subjected to the pseudo gradation process is recorded.

Next, the separation processing of the multiplexed additional information, which is executed by the separation apparatus having the configuration shown in FIG. 2B, will be described with reference to the flowchart shown in FIG.

First, in step s300, the scanner scans the printed matter on which the image is recorded to read the image, and in step s301, extracts the color component to which the sign is added from the image information obtained in step s300. Do.

Next, in step s302, the vertical direction (i (row) direction) and the horizontal direction (j (column) direction) of the image information
Variables (i) and (j) that count the addresses of
Initialize to “0”. In step s303, it is checked whether or not the value indicated by the address variable (i) is a row to which a sign is added. In the following step s304, the value indicated by the address variable (j) is set to a column in which the sign is added. Find out if. These steps s303 and s304
In, if it is determined that both the address variables (i) and (j) are addresses to which the sign is added, the process proceeds to step s305. On the other hand, step s3
03 or s304, the address variable (i),
If it is determined that at least one of (j) is not the address where the sign is added, the process proceeds to step s30
The process skips steps 5 to s308 and proceeds to step s309.

In step s305, the average pixel value in an arbitrary local area in the sign addition area is measured.
Further, the difference between the maximum value and the minimum value of the local average pixel value is calculated, and in the following step s306, the average pixel value of the entire sign added area is measured. Further, in step s307, a threshold value for determining the sign is obtained based on the average pixel value obtained in step s306, and in step s308, the difference between the local average pixel value obtained in step s305 and step s307. The sign is determined by comparing the obtained threshold value. Thereafter, the process proceeds to step s309.

At step s309, it is checked whether or not codes that have not been separated remain. If it is determined that unseparated codes remain, the process proceeds to s310
However, if it is determined that there are no unseparated codes, the separation processing ends.

In step s310, the address variable (j)
Is incremented by "+1", and in step s311, it is determined whether the processing in the column direction has been completed. Here, for the same value of the address variable (i), if the processing in the column direction has not been completed, the processing returns to step s304, and the above processing is repeated. On the other hand, if the process has been completed, the process proceeds to step s312, the address variable (j) in the column direction is initialized to “0”, and furthermore, the process proceeds to step s31.
3, the count value of the address variable (i) in the row direction is set to "+".
1 ".

Then, in step s314, it is checked whether or not the image information has been completed. If it is determined that the image information has not been completed, the process returns to step s303. The information separation processing ends.

In the above processing, step s3
05 may be performed after step s306 or step s307. If the end of the code can be detected by checking the information after the separation processing, step s3
09 can be omitted.

Next, the details of the pseudo gradation process in the sign addition area will be described more specifically with reference to FIG.

FIG. 5 is a diagram showing a state in which image data in which one pixel is represented by 8 bits is binarized by using an error diffusion method, and a code indicating additional information is multiplexed during the binarization processing. Here, as shown in FIG.
Consider image data of (ie, pixel value 128). FIG.
(B) shows an image when binarized using the error diffusion method,
FIG. 5C shows an image to which a sign is added at the time of the binarization.

It is assumed that the code value is distinguished depending on whether or not there is a set of artificially created identical quantization values. The artificially created quantization value is determined by the average density of the image around the pixel to which the sign is added, and when the average density of the image is high, the quantization value representing the minimum density (ie, “0”) is determined. If the average density of the image is low, a quantization value representing the highest density (that is, "255") is selected.

[0060] image shown in FIG. 5 (a) but would may choose which of the quantized values for an intermediate concentration, wherein as to create a quantized value representing the lowest concentration ( "0") I do. When an ink jet printer or the like is used as the printer engine of the printer 150, ink dots spread on the recording medium when an image is recorded on the recording medium. The average density in the periphery is not always 50%. In other words, the range of pixels for artificially creating a quantization value as shown in FIG. 5C is determined by the resolution ratio between the recording device and the image reading device.

According to the sampling theorem, the minimum condition of the range in which the quantization value should be artificially created is half the resolution of the image reading apparatus. In the case where the size of a pixel calculated from the resolution of a printing apparatus due to the spread of ink on a printing medium and the size of an ink dot or a blank area without ink on the medium are different, as in an ink jet printer or the like. Instead of the resolution of the printing apparatus, the size of ink dots or the size of a blank area may be used.

In this embodiment, as shown in FIG. 5C, a region (a set of artificially same quantized values) 400 having a size of 3 (horizontal) × 2 (vertical) images is created. At this time, when the binarization process is performed by applying the error diffusion method, an attempt is made to preserve the density of the image information, so that an area 401 is generated in which the density is inverted from the artificially created quantization value. Although the shape and size of the density reversal region 401 are various, the size of the region 401 is affected by the size of the region 400 because the region 401 is a factor that erases the density of the region 400 created artificially. Become wider. Then, the region 400 and the region 401
Are formed with the same quantized value, the addition of the sign causes areas where the average density is low and high at the same time, regardless of the average density of the sign-added area.

The average density of the image shown in FIG. 5A is, for example, "90" or "150". Even if the area is changed, the local low-density and high-density areas appear at the same time while the average density of the sign-added area is maintained. As a result, even after recording by an ink jet printer or the like, local low-density and high-density areas simultaneously appear in the sign addition area.

Now, in an image obtained by an image reading device such as a scanner, if attention is paid to the average pixel value of pixels in a range corresponding to the artificially created region 400 in the sign added region, The difference between the average pixel values of the pixels including the region 401 increases.

On the other hand, as shown in FIG. 5 (b), when the region where the same quantized value is artificially created is not created, the same quantized value is dispersed due to the nature of the error diffusion method. The average pixel value in the range corresponding to the area is substantially the same as the average pixel value of the original image (FIG. 5A). When the sign is added, the area 40 is added in the sign added area.
Since the region 0 and the region 401 are regions having locally the maximum average pixel value and the minimum average pixel value, respectively, the average pixel value in the range corresponding to the size of the code artificially created in the code addition region is checked. By comparing the difference between the maximum value and the minimum value of the average pixel values with a threshold value, it is possible to determine the code value.

Since the distribution state of the pixel values differs depending on the average pixel value in the sign added area, the threshold value changes depending on the average pixel value. Therefore, the threshold is measured in advance for each concentration by an experiment. The size of the area 400 is determined not only by the resolution ratio of the recording apparatus and the image reading apparatus, but also by the area 4.
The detection accuracy is improved by creating the image data 01 in such a size that the image reading device can detect the image data.

Now, due to a rapid change in density at an edge portion of an image or the like, the same quantized value may not be dispersed even if a code is not artificially added. Therefore, image processing may be performed so as to forcibly disperse the same quantization value in an edge portion or the like.

Therefore, according to the above-described embodiment, code addition is performed using the minimum necessary pixel set in the reading device in consideration of the reading resolution of the device that reads the recorded image. The information can be reliably read, and the deterioration of the image quality due to the addition of the sign can be minimized.

<Second Embodiment> FIG. 6 is a block diagram showing the configuration of a multiplexer for multiplexing additional information with image information and recording an image according to the second embodiment. FIG.
Here, the same components as those already described in the above-described embodiment are denoted by the same reference numerals, and description thereof will be omitted.

As can be seen by comparing the configuration of FIG. 6 with that of FIG. 2A, in the above-described embodiment, the same as the pseudo-gradation image obtained by quantizing one color component having image information. Although the code is represented by creating a set of pixels having a quantization value, in the second embodiment, the code is represented by a color component in which a set of pixels having the same quantization value is artificially created. Express.

In this embodiment, it is assumed that when the value (bit) to be embedded is “0”, the yellow component is embedded, and when the value (bit) is “1”, the process is performed on the magenta component. However, it is desirable to apply a color component to be embedded to a color component to which human vision is insensitive.

The configuration of the apparatus shown in FIG.
08 detects the color component currently being processed from the image information, and the quantization condition determination unit 101a determines the quantization value in consideration of the output result of the color component detection unit 108, that is, the state of the bit to be embedded ( 0 or 1) and a part for determining the consistency between the color component to be embedded and the color component to be embedded is added.

Next, with reference to the flowchart shown in FIG. 7, a description will be given of a process of multiplexing codes representing additional information according to this embodiment. In FIG. 7, the same processing steps as those shown in FIG. 3 are not described, but are given the same step reference numbers. In particular, steps s200 to s201, step s207,
Also, the processing of steps s210 to s215 is not described.

According to the flowchart shown in FIG. 7, after steps s200 to s203, in step s600, it is checked whether or not the color component currently being processed is a color component used for expressing a code. Here, if it is determined that the color component is a color used for expressing the code, the process proceeds to step s601; otherwise, the process proceeds to step s209.

In step s601, with respect to the code to be processed (code “0” or “1”), it is determined whether or not a set of the same quantization values should be created for the color component currently being processed. If it is determined that the color component is to be created, the process proceeds to step s204,
If not, the process proceeds to step s
Go to 209.

After step s204 or s209, the same processing as that shown in FIG. 3 is executed.

As described above, according to the second embodiment, even if the set of identical quantization values created by the area of the minimum unit recognizable by the image reading apparatus is code “1”, code “0” is set. Can also be used.

Therefore, the code is determined based on the same set of quantized values or the variance in the above-described embodiment. However, an ambiguous state is less likely to occur, and a more reliable code can be detected. .

<Third Embodiment> The third embodiment is characterized in that an object to which additional information is added is an area where a certain color component (for example, a yellow component) is hardly visually detected. . The region that is difficult to detect is different in the appearance of the code depending on how the surrounding ink is applied in a printed matter by a printing device such as an inkjet printer. For example, in a low-density part of an image, since there is little opportunity for ink to be ejected from that area, it is conspicuous if ink ejection according to the code is performed in order to embed code information in that area. It will be easier. However, in the medium density region, it means that an appropriate amount of ink is ejected in a peripheral portion, so that even if information is embedded in that portion, it is relatively inconspicuous. This is the third book
It is utilized in the embodiment. That is, the middle density portion of the image to be recorded is set as a code embedding target.

More specifically, for example, the quantization condition determination unit in FIG. 6 determines that the average density of the yellow component that can be derived from the input image, including the surrounding pixels surrounding the pixel of interest, is the intermediate density. It is determined whether it is between the two threshold values, and if it is within the range, it is determined that it is a medium density portion, and is determined as a code embedding target.

Even if the average density around the pixel of interest is not medium density for a certain color component, if the average density around the pixel of interest is medium density for another color component, the color for embedding the code The code may be embedded in the medium density area by changing the components. Further, even when it is determined that all the color components are not the medium density, the code embedding may be performed on the color component whose average density around the target pixel is closest to the medium density.

As a result, according to the third embodiment,
It is possible to add codes that are hard to detect visually, and as a result, it is also possible to minimize deterioration of image quality.

<Fourth Embodiment> FIG. 8 is a main block diagram of the fourth embodiment. In the fourth embodiment, when a plurality of types of additional information are input, they are added to different color components for each type.

FIG. 9 is a diagram showing how different types of information are added to the respective color components constituting the input image. According to FIG. 9, the cyan (C) component 901 of the input image information 900
, Audio information is added, character information is added to the magenta (M) component 902 of the input image information 900, and copyright information is added to the yellow (Y) component 903 of the input image information 900. The image information (output image) 904 at the time of the printing process in which the information 901, 902, and 903 of each color component multiplexed with the image data is synthesized.

Next, with reference to the flowchart shown in FIG. 10, a description will be given of a process of multiplexing codes representing additional information according to the fourth embodiment. Note that, in FIG. 10, the same processing steps as those shown in FIG. 3 are not described, or are given the same step reference numbers. In particular, steps s200 to s201, step s
207 and the processing of steps s210 to s215 are not described.

According to the flowchart shown in FIG. 10, after steps s200 to s203, in step s800, a plurality of pieces of input additional information are classified for each color component to be added. Then, based on the result of step s800, in step s801, the current color component is input, and it is checked whether the color component is the color component to which the classified information is added. Here, if it is determined that the color component currently being processed is a color component to which information is to be added, the process proceeds to step s204. If it is determined that the color component is not a color component to which a code is to be added, the process proceeds to step s209. Proceed to.

Step s204 or step s2
After 09, the same processing as that shown in FIG. 3 is executed.
Note that the process of step s800 may be performed before step s203.

As described above, according to the fourth embodiment, it is possible to add a plurality of types of information to one piece of image information. In addition, since image processing only needs to be performed for a color component to which information is added, processing can be performed efficiently. It should be noted that the color components to which the sign is added and the additional information are not limited to those shown in the example of FIG. 9 and may be any combination. Even if the information is of the same type (for example, character information), information having different contents may be added separately to different color components.

Further, as a target for embedding information to be added, the third embodiment described above may be used.

<Fifth Embodiment> Here, the multiplexing process of the additional information is performed by using the device having the same configuration as that of the first embodiment. In the multiplexing, in the first embodiment, the pseudo gradation expression is performed. In contrast to the error diffusion method, the systematic dither method is used for the pseudo gradation expression.

When the error diffusion method is used for pseudo gradation expression, for example, as shown in FIG. 5C, when the region 400 is artificially created, the region 401 naturally occurs due to the distribution of accumulated errors. On the other hand, when the systematic dither method is used, it is necessary to create a threshold matrix such that a region having two types of continuous pixels having the same quantization value occurs when a code is added.

FIG. 11 is a diagram showing an example of a dither matrix and an example of an image in which additional information is multiplexed and binarized by a dither method. In FIG. 11, (a) is an example of a threshold matrix of the systematic dither method when performing sign addition,
(B) is an example of an image binarized using the dither matrix shown in (a).

In the dither matrix shown in FIG. 11A, the threshold value “X” is set to a high value and the binarization result is always “0”.
, And the threshold “Y” is set to a low value so that the binarization result always becomes “1”. When binarization processing is performed using such a matrix, FIG.
As shown in (b), a region 1000 and a region 1 each composed of a plurality of pixels having the same quantization value whose density is inverted from each other
001 can be artificially created.

When a code is expressed by the presence or absence of a combination of regions composed of a plurality of pixels having the same quantization value with inverted densities, when the region 1000 and the region 1001 are not added, the same quantum is forcibly applied. What is necessary is just to use a threshold matrix which does not make the pixel values continuous for a plurality of pixels.

According to the embodiment described above, since the dither method is used for the pseudo-gradation expression, processing such as error distribution is not required, and not only can sign addition be performed at a higher speed than in the error diffusion method, Sign addition can be performed reliably regardless of the pixel value state of the sign addition area.

Further, the dither method used in this embodiment may be applied to the second and third embodiments.

The present invention can be applied to a system including a plurality of devices (for example, a host computer, an interface device, a reader, a printer, etc.), but can be applied to a single device (for example, a copier, a facsimile). Device).

Further, an object of the present invention is to supply a storage medium (or a recording medium) recording software program codes for realizing the functions of the above-described embodiments to a system or an apparatus, and to provide a computer (a computer) of the system or the apparatus. It is needless to say that the present invention can also be achieved by a CPU or an MPU) reading and executing the program code stored in the storage medium. In this case, the program code itself read from the storage medium implements the functions of the above-described embodiment, and the storage medium storing the program code constitutes the present invention. Also,
When the computer executes the readout program code, not only the functions of the above-described embodiments are realized, but also the operating system (OS) running on the computer based on the instructions of the program code.
It goes without saying that a case where the functions of the above-described embodiments are implemented by performing some or all of the actual processing, and the processing performs the functions of the above-described embodiments.

Further, after the program code read from the storage medium is written into a memory provided in a function expansion card inserted into the computer or a function expansion unit connected to the computer, the program code is read based on the instruction of the program code. Needless to say, the CPU included in the function expansion card or the function expansion unit performs part or all of the actual processing, and the processing realizes the functions of the above-described embodiments.

When the present invention is applied to the storage medium, the storage medium stores program codes corresponding to the flowcharts described above (shown in FIGS. 3, 4, 7, and 10). become.

[0101]

As described above, according to the present invention, when multiplexing the additional information with the image information, the minimum readable value of the image reading device is considered in consideration of the resolution of the image output device and the image reading device. Since the multiplexing is performed using the pixel set, when the multiplexed image is read by the image reading device, for example, even if the reading device is a popular low-resolution scanner, the additional information is more reliably provided. Can be separated and read, and the image quality deterioration due to the multiplexing can be minimized.

Further, by adding predetermined information adaptively based on the resolution at which the output image can be reliably read, the additional information can be read reliably.

Further, since a plurality of different pieces of additional information can be added to different color components of an image signal, a plurality of types of information can be added to one piece of image information.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of an image processing apparatus according to a preferred embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a multiplexing device that multiplexes additional information with image information and records an image, and a separating device that reads an image in which the additional information is multiplexed and separates the additional information.

FIG. 3 is a flowchart showing a sign adding process according to the first embodiment.

FIG. 4 is a flowchart showing a code separation process according to the first embodiment.

FIG. 5 is a diagram illustrating an example of a quantization result of image information according to the first embodiment.

FIG. 6 is a block diagram illustrating a configuration of a multiplexing apparatus that multiplexes additional information with image information and records an image according to a second embodiment.

FIG. 7 is a flowchart illustrating a sign adding process according to a second embodiment.

FIG. 8 is a block diagram illustrating a configuration of a multiplexing device that records additional information by multiplexing additional information with image information according to a third embodiment.

FIG. 9 is a diagram illustrating a state in which different information is added to each color component forming an input image.

FIG. 10 is a flowchart showing a sign adding process according to a third embodiment.

FIG. 11 is a diagram illustrating an example of a dither matrix according to a fourth embodiment and a binarization result using the matrix.

[Explanation of symbols]

 101, 101a, 101b Quantization condition determination unit 102 Quantization unit 103 Code addition color extraction unit 104 Code addition area detection unit 105 Threshold value selection unit 106 Pixel value distribution state detection unit 107 Code determination unit 108 Color component detection unit 109 Information classification unit 200 image information input terminal 201 additional information input terminal 202 scanner resolution input terminal 203 printer resolution input terminal 204 code addition position condition input terminal 205 additional information output terminal after separation

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[Procedure amendment]

[Submission date] December 25, 2000 (200.12.
25)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claim 1

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[Correction target item name] Claim 4

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[Correction target item name] Claim 9

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[Correction target item name] Claim 15

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[Procedure amendment 5]

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[Correction target item name] Claim 23

[Correction method] Change

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Claims (31)

[Claims] 1. An image processing apparatus for multiplexing additional information with image information, comprising: a first input unit for inputting the image information; a second input unit for inputting the additional information; In consideration of the resolution of the image output device that outputs as the image and the resolution of the image reading device that reads the image output from the image output device, the additional information is represented by a minimum set of pixels that can be read by the image reading device. Quantifying means for multiplexing the additional information with the image information to perform pseudo gradation processing, and output means for outputting image data subjected to pseudo gradation processing by the quantization means. Image processing apparatus. 2. The image processing apparatus according to claim 1, wherein the pseudo gradation processing is performed according to an error diffusion method. 3. The image processing apparatus according to claim 1, wherein the pseudo gradation processing is performed according to a dither method. 4. A set of pixels expressing the additional information generated by the quantization means is composed of continuous pixels,
2. The continuous pixel according to claim 1, wherein the continuous pixel has a first quantization value, and a size of the continuous pixel having the first quantization value is determined in consideration of a resolution of an image reading device. Image processing device. 5. The set of continuous pixels having the first quantization value, such that the quantization means stores an average density of image information in a peripheral area of a pixel on which the additional information is multiplexed. 5. The method according to claim 4, further comprising: generating a set of adjacent pixels having a second quantization value that compensates for the density represented by the set of continuous pixels having the first quantization value. Image processing device. 6. The additional information multiplexed in the image information is obtained by a combination of a set of continuous pixels having the first quantization value and a set of continuous pixels having the second quantization value. The image processing apparatus according to claim 5, wherein the image processing apparatus is expressed. 7. The image processing apparatus according to claim 1, wherein the additional information is added to one of a plurality of color components forming the image information. 8. A density of a neighboring pixel at a position where the additional information is added is checked for each of the plurality of color components, and based on an average density of the neighboring pixels, it is difficult to visually recognize the plurality of color components. The image processing apparatus according to claim 7, further comprising a selection unit that selects a color component as a color component of the image information for multiplexing the additional information. 9. When the second input means inputs a plurality of pieces of additional information, the additional information is classified so that different color components of the image information are multiplexed for each of the plurality of pieces of additional information. The image processing apparatus according to claim 7, further comprising a classifying unit that performs the following. 10. An image processing apparatus for reading an image in which additional information is multiplexed and separating the additional information, comprising: reading means for reading the image; and detecting a position where the additional information is multiplexed in the image. And a separating unit for specifying an additional information multiplexing position of the image based on a detection result by the detecting unit and separating the additional information from the specified position. Processing equipment. 11. The apparatus according to claim 1, wherein the detecting means reads a predetermined dot pattern recorded in a predetermined area of the image to detect a multiplexing position of the additional information.
0. The image processing apparatus according to 0. 12. The image processing apparatus according to claim 10, wherein the detecting unit regards a position determined according to a predetermined image format as a position where the additional information is multiplexed. 13. The apparatus according to claim 10, wherein said reading means is a scanner. 14. The separating unit includes: a measuring unit that measures a difference between an average density value near the specified additional information multiplexing position and a maximum value and a minimum value of a local average pixel value; 11. The image processing apparatus according to claim 10, wherein a value of a code representing the additional information is extracted based on the measured average density value and the difference. 15. The apparatus according to claim 15, wherein the separating unit further includes a selecting unit that selects one of a plurality of thresholds based on the average density value, and compares the difference selected by the selecting unit with the difference. The image processing apparatus according to claim 14, wherein the value of the code is extracted. 16. An image processing method for multiplexing additional information with image information and separating the additional information from an image in which the additional information is multiplexed, comprising: a first input step of inputting the image information; A second input step of inputting the additional information; and taking into account a resolution of an image output device that outputs the image information as an image and a resolution of an image reading device that reads an image output from the image output device. A quantization step of multiplexing the additional information with the image information so that the information is represented by a minimum set of pixels that can be read by the image reading device, and performing a pseudo gradation process; Outputting an image by forming an image based on the obtained image data, reading the image, and detecting a position where the additional information is multiplexed in the image. And a separating step of specifying an additional information multiplexing position of the image based on a detection result in the detecting step and separating the additional information from the specified position. 17. A set of pixels representing the additional information generated in the quantization step is composed of continuous pixels, the continuous pixels have a first quantization value, and the first quantization value is 17. The method according to claim 16, wherein the size of the continuous pixels is determined in consideration of the resolution of the image reading device.
The image processing method according to 1. 18. The method according to claim 18, wherein the quantizing step is performed on a set of consecutive pixels having the first quantization value so as to preserve an average density of image information in a peripheral area of the pixel on which the additional information is multiplexed. 18. The method according to claim 17, wherein adjacent sets of continuous pixels having a second quantization value are generated to compensate for the density represented by the set of continuous pixels having the first quantization value. Image processing method. 19. The additional information multiplexed in the image information is obtained by a combination of a set of continuous pixels having the first quantization value and a set of continuous pixels having the second quantization value. The image processing method according to claim 18, wherein the image processing method is expressed. 20. The separating step, comprising: a measuring step of measuring a difference between an average density value in the vicinity of the specified additional information multiplexing position and a maximum value and a minimum value of a local average pixel value; 17. The image processing method according to claim 16, wherein a code value representing the additional information is extracted based on the measured average density value and the difference. 21. The separation step further includes a selection step of selecting one from a plurality of thresholds based on the average density value, and comparing the difference selected in the selection step with the difference. 21. The image processing method according to claim 20, wherein a value of the code is extracted. 22. Multiplexing of additional information with image information,
And / or a computer-readable memory storing a program for executing image processing for separating the additional information from an image in which the additional information is multiplexed, wherein the program is a first input process for inputting the image information A code for executing the second input process for inputting the additional information, a resolution of an image output device for outputting the image information as an image, and an image reading device for reading an image output from the image output device In consideration of the resolution of the image reading device, the additional information is multiplexed with the image information so that the additional information is represented by a minimum set of pixels that can be read by the image reading device, and a process of performing pseudo gradation processing is performed. A code to execute, a code to execute a process of forming an image based on the image data subjected to the pseudo gradation process and outputting an image, and a process of reading the image. A code for executing a reading process to be taken; a code for executing a detection process for detecting a position where the additional information is multiplexed in the image; and And a code for executing a separating process for separating the additional information from the specified position. 23. An image processing method for multiplexing additional information with image information, comprising: a first input step of inputting the image information; a second input step of inputting the additional information; In consideration of the resolution of the image output device that outputs as the image and the resolution of the image reading device that reads the image output from the image output device, the additional information is represented by a minimum set of pixels that can be read by the image reading device. A quantization step of multiplexing the additional information with the image information so as to perform pseudo gradation processing, and an output step of outputting image data subjected to pseudo gradation processing in the quantization step. Image processing method. 24. A computer-readable memory storing a program for executing image processing for multiplexing additional information on image information, wherein the program includes: a code for executing first input processing for inputting the image information; A code for executing a second input process for inputting the additional information, a resolution of an image output device that outputs the image information as an image, and a resolution of an image reading device that reads an image output from the image output device are taken into consideration. A code for multiplexing the additional information with the image information so that the additional information is represented by a minimum set of pixels that can be read by the image reading device, and executing a quantization process of performing pseudo gradation processing. A code for executing an output process of outputting image data subjected to the pseudo gradation process by the quantization process. Li. 25. The image processing apparatus according to claim 1, wherein the additional information is represented by a color component for which a set of pixels is generated by the quantization unit. 26. An input unit for inputting an image, an adding unit for adding predetermined information to the image input by the input unit, and an output for outputting an image to which predetermined information is added by the adding unit. Means for adding the predetermined information based on the resolution at which the image output by the output means is read. 27. An input step of inputting an image, an adding step of adding predetermined information to the image input in the input step, and an output of outputting an image to which predetermined information has been added in the adding step. An image processing method, wherein, in the adding step, the predetermined information is applied adaptively based on a resolution at which an image output in the output step is read. 28. A computer-readable memory storing a program for executing image processing, the program comprising: a code for performing input processing for inputting an image; and a predetermined information for the image input in the input processing. And a code for performing output processing for outputting an image to which predetermined information has been added in the additional processing. In the additional processing, an image output in the output processing is read. A computer readable memory, wherein said predetermined information is adaptively added based on a resolution obtained. 29. An image processing apparatus for adding predetermined information to image information, comprising: input means for inputting image information; and a plurality of different pieces of predetermined information of the image information input by the input means. An image processing apparatus comprising: an adding unit that adds different color components. 30. An image processing method for adding predetermined information to image information, comprising: an input step of inputting image information; and a plurality of different pieces of predetermined information each of which is input to the image information input in the input step. An adding step of adding to different color components. 31. A computer-readable memory storing a program for executing image processing for adding predetermined information to image information, wherein the program is different from a code for performing input processing for inputting image information. A code for performing an addition process of adding a plurality of predetermined information to different color components of the image information input in the input process.