JP3570236B2 - Image processing method and storage medium storing the program - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an information embedding method for embedding arbitrary information in content, particularly without deteriorating the content.
[0002]
[Prior art]
Although information embedding technology in contents has been developed for various contents (that is, digitized data) such as images, sounds, texts, and drawings, embedding information in images is taken up as a representative example here. In general, information embedding in an image is performed, for example, by making a slight change to a value such as the luminance of a pixel as described in IBM System Journal, Vol. 35, No. 3 & 4, pp. 313-336, 1996. Information is embedded.
[0003]
Regarding this value change, there are the following requirements from a practical point of view.
[0004]
(1) A value change cannot be detected by human vision. (Or, even if it can be detected, it does not interfere with human image reference)
(2) Even if an image in which information is embedded is subjected to processing such as JPEG compression, the embedded information is not lost.
[0005]
In the conventional information embedding technology, as described in the above-mentioned document, in order to satisfy this requirement, a device for changing a value to be changed is devised. That is, the value is changed so that the change is hardly noticeable and hardly disappears. For example, an image is expressed in frequency, and a change is made to the coefficient of the mid-range component.
[0006]
[Problems to be solved by the invention]
The relationship between the change in the value of the image and the visual change differs for each image and also for each region in the image. For example, a small value change is conspicuous in a flat region, while a large value change is not conspicuous in a cluttered region such as a forest photograph.
[0007]
However, the above-described conventional technique is insufficient in optimizing the magnitude of the value change depending on the nature of the image. Therefore, when giving priority to prevention of a visual change, it is necessary to reduce the value change assuming a flat image, and the resistance to image processing is low. On the other hand, when priority is given to tolerance to image processing, it is necessary to increase the value change, and a visual change occurs in a flat image. That is, in the conventional method, it is difficult to achieve both the prevention of the visual change and the resistance to the image processing.
[0008]
An object of the present invention is to provide a method capable of preventing both a visual change and resistance to image processing in embedding information in content, a program for realizing the method, or an apparatus for executing the method and the program. That is.
[0009]
[Means for Solving the Problems]
In the field of medical image processing, a filter for facilitating a doctor's diagnosis of a photograph of a human body taken using X-rays or MRI has been studied. The most advanced medical filters have the following properties, as shown in IEICE Transactions, D-2, J79-D-2, No. 8, pages 1347 to 1353.
[0010]
(1) Noise is removed by a smoothing process.
(2) Shapes are preserved for edge information that is important for human vision, that is, for parts where the outline or surface properties of an object change, and for points (isolated points) where the color or brightness is particularly different from the surroundings.
In other words, the medical filter can be considered to have the following properties.
(1) The value of the image changes.
(2) The image does not change visually. Or, even if it changes, it does not hinder human reference.
[0011]
It was conceived to solve the above-mentioned problem by utilizing the properties of the medical filter. That is, in the information processing system having a means for inputting content and a means for embedding information in the content, the above-mentioned problem is solved by using the above-mentioned medical filter, which cannot be perceived by a human or obstructs human content reference. Resolving by changing the value of the content that does not need to be changed, setting the range between the value before the change and the value after the change as the changeable range of the value for embedding information, and embedding the information by changing the value of the content within this changeable range it can.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. In this embodiment, a still image is targeted, and information is embedded by changing the luminance of a pixel.
[0013]
FIG. 1 is a functional configuration diagram of the present invention. Elements indicated by rectangles, ie, input / output 101, changeable range calculation 103, and information embedding 105 are processes, and are realized by the CPU of the computer. Elements indicated by ellipses, that is, the image 102, the changeable range 104, and the watermarked image 106 are data, and are realized by a storage device of a computer.
In the following, information in which information is associated with some pattern that cannot be detected by a human is called a watermark, and an image in which information is embedded is called a watermarked image.
[0014]
The input / output processing 101 inputs an image and stores it in a storage device. In the changeable range calculation process 103, first, the above-described medical filter or image processing similar to the above is applied to the image data 102. As a result, an image having a luminance different from that of the image data 102 and not visually changing is obtained. Next, the changeable range calculation processing 103 stores, for each pixel, the luminance before application of the image processing and the luminance after application of the image processing. This is the changeable range data 104.
[0015]
The information embedding process 105 first selects a pixel of which luminance is to be changed among the pixels of the image data 102. Next, for each selected pixel, information is embedded by changing the luminance to a specific value. As a result, the information insertion image data 106 is obtained. The information insertion image data 106 is output to the outside via the input / output processing 101.
[0016]
The outline of the above medical filter is as follows.
(1) The processing of (2) to (3) is performed for each pixel in the image.
Note that a pixel is a minimum partial image forming an image, and is generally expressed by luminance and two types of color differences or three types of colors (three primary colors). Here, it is assumed that a pixel is composed of luminance and color difference.
(2) Analyzing the luminance of the pixel and surrounding pixels, and obtaining a normal vector of the luminance at the pixel. This vector represents the direction in which the change in luminance is maximum. A vector orthogonal to this vector and passing through the pixel represents a direction in which the change in luminance is minimum, that is, an edge passing through the pixel.
(3) One-dimensional smoothing processing is performed along the edge.
Through the above processing, the medical filter has the above-described properties.
The changeable range calculation processing 103 obtains an image that is different in luminance from the image data 102 and does not visually change.
[0017]
Next, a method of changing luminance in the information embedding process 105 will be described with reference to FIG. Here, it is assumed that the luminance value of one pixel is from 0 to 255. FIG. 2 shows the luminance value of a pixel by a number line. In this embodiment, a white circle on the number line, that is, a point whose value is a multiple of 16, corresponds to the embedding information 0, and a black point, that is, a point whose value is a multiple of 16 + 8, corresponds to the embedding information 1. And
[0018]
The information embedding process 105 inserts information by changing the luminance of the pixels of the image data 102 to the nearest white or black circle. That is, if the information to be embedded in the pixel is 0, it is changed to a white circle, and if it is 1, it is changed to a black circle. For example, if the luminance of a pixel is △ in the figure, ie, 30 and the information to be embedded is 0, the luminance of the pixel is changed to 32, and if the information to be embedded is 1, the luminance is changed to 24. I do.
[0019]
Next, the use of the changeable range data 104 will be described. In the above-described basic operation, there is a case where the change in the luminance of the pixel is too large and the image visually changes. To prevent this, the pixel value is changed within the changeable range data 104. For example, it is assumed that the luminance of a pixel is Δ, that is, 30 and the changeable range of the luminance of the pixel is 26 to 33. In this case, if the information to be embedded is 0, the luminance of the pixel is changed to 32 as in the above basic operation. However, when the information to be embedded is 1, the luminance 24 of the change destination is not included in the changeable range, and therefore, is changed to a value 26 closest to 24.
[0020]
Finally, extraction of information from the watermark-inserted image data 106 will be described. First, a pixel whose value is to be referred to is selected. In this pixel selection, the same rule as that of the pixel selection in the information embedding process 105 is used. Therefore, a pixel whose luminance has been changed is selected.
[0021]
Next, for each selected pixel, its luminance is extracted, and it is determined whether the embedded information is 0 or 1 depending on which value is closer to a multiple of 16 (multiple of 16 + 8).
[0022]
As described above, in the information embedding processing 105, since the luminance is changed in the changeable range data 104, the luminance may not be accurately changed to a multiple of 16 or (multiple of 16 + 8). Therefore, an error occurs at a certain probability in information extraction. This problem can be solved by overlappingly embedding the same information in a plurality of pixels and performing a majority decision in extraction.
[0023]
As described above, according to the present embodiment, information can be embedded in an image, and the embedded information can be extracted. In this information embedding, the value of the image can be changed only in a range in which there is no visual deterioration of the image, that is, in a changeable range. Further, since the changeable range is calculated for each pixel, by changing the value as large as possible for each pixel, it is possible to enhance the resistance to image processing.
[0024]
According to this embodiment, in a system that embeds information in a still image by changing a brightness value, a brightness value change range without visual deterioration can be obtained for each pixel, and the brightness value can be changed within that range. As a result, there is no visual deterioration of the image as in the case where the luminance is uniformly changed to a large degree, while the insertion information is not easily removed as in the case where the luminance is uniformly changed to a small level. This makes it possible to prevent both deterioration of image quality and durability of embedded information.
[0025]
Next, a second embodiment of the present invention will be described with reference to FIGS.
[0026]
The present invention optimizes the amount of value change when information is inserted by changing the value of an image. It does not depend on the type of image, the type of image value to be changed, the type of information to be inserted, or the method of expressing the inserted information in the image, and can be combined with any image, image value, information type, and expression method. Here, the following case is considered as an example.
[0027]
(1) Image Type Here, moving image data is considered. This moving image data is composed of 30 still images per second. Each still image is 720 × 480 pixels. In the present embodiment, still images are extracted one by one from the moving image data, and information is inserted therein. The information insertion process is completed for each still image.
(2) Value of image to be changed The luminance value of each pixel of the still image is changed.
(3) Information to be inserted 6-bit information, that is, 64 types of numbers from 0 to 63.
(4) Expression of Information in Still Image (a) Selection of Block The still image is divided into blocks of 8 × 8 pixels. In the case of a still image of 720 × 480 pixels often used for contents, the still image is divided into 90 × 60 (= 5400) blocks. For each of the 64 types (6 bits) of insertion information, the corresponding relationship of which block (at least one) of the 5400 blocks to change in value (this is determined in advance and stored in a table, for example) Select a block based on. Change the brightness of the pixels in the selected block.
[0028]
(B) Change of brightness in block The brightness of each pixel is changed so that the sum of the brightness of the 64 pixels in the selected block is n times the nearest integer A. A is a value designated by the user of this embodiment. Here, 512 is used.
At the time of extracting information, still images are extracted one by one from the moving image in which the information is inserted, and information is extracted from each still image.
When image processing such as compression is performed after embedding information by the above-described method, the luminance changes, and the value may not be exactly n times the positive number A at the time of extraction. Therefore, in information extraction from a still image, it is determined whether or not the luminance is n multiples of A or in the vicinity thereof for each of the 5,400 blocks.
Note that the neighborhood is defined as (A × n−A / 4) or more and (A × n + A / 4) or less. This definition is an example, and other definitions are possible.
If image processing such as compression is not performed on an image in which information is embedded and a luminance change does not occur, a neighborhood need not be defined.
In the case of n multiples of A or in the vicinity thereof, it is determined that the luminance of the block has been changed. One of the inserted 64 types of information is specified by using information indicating which of the 5400 blocks has changed the luminance and the above-described correspondence relationship.
[0029]
In the above extraction, if the sum of the luminances of the blocks happens to be an n-times multiple of A even though the luminance is not changed, this may cause erroneous detection. In order to prevent this, a plurality of brightness change blocks are used, and majority logic is used. Among the blocks, the block whose sum of block brightness is n times or more than A is a predetermined value (for example, half) or more. Is determined to have a watermark embedded therein.
The method of the above-mentioned information expression, insertion, and extraction uses the method of Japanese Patent Application No. 09-238030. In the following, a method of optimizing the amount of change in luminance will be described on the premise of the above-described information expression, insertion and extraction methods.
FIG. 11 is a hardware configuration diagram of this embodiment. The input / output device 1101 is realized by an I / O device of a computer or the like. The moving image and information to be embedded are input to the outside and stored in the storage device 1103 via the arithmetic device 1102. Also, a moving image in which information is embedded is received from the arithmetic unit 1102, and this is output to the outside. The arithmetic unit 1102 is realized by a CPU of the computer, reads out a moving image and information to be inserted stored in the storage device 1103, inserts information into the moving image, and outputs the resulting moving image to the input / output device 1101. At this time, information is embedded using the above-described filter so that there is no visual deterioration of the image. The storage device 1103 is realized by a semiconductor, a hard disk, an optical disk, or the like, and stores a moving image and information to be inserted.
[0030]
FIG. 3 is a functional configuration diagram of the second embodiment.
Blocks 301 to 306 are processing performed by the arithmetic unit 1102, and are realized by the CPU of the computer executing the program. Blocks 307 to 313 are data, which are stored in the memory of the computer, that is, the storage device 1103.
This program can be distributed in a state recorded in a storage medium, or distributed from a server via a network. Further, this program can be configured to operate under the operating system of a personal computer.
[0031]
The input / output 301 receives the moving image data 307 and stores it in the memory. This moving image data is a sequence of a plurality of continuous still images. Each still image is 720 × 480 pixels.
The input / output 301 inputs information 310 to be inserted into an image and stores the information 310 in a memory. The information to be inserted is 6-bit information. That is, the information to be inserted is 2 6 = 64 types.
Further, the input / output 301 receives, from the input / output device 1101, a value (the above-described integer A) 312 which is a reference when inserting information into an image, and stores the value in the memory. Here, the value of the integer A is 512. The n multiple of this positive number A is hereinafter referred to as an adsorption value.
On the other hand, the input / output 301 reads the moving image 313 into which the watermark information has been inserted, from the memory, and outputs it from the input / output device 1101 to the outside.
[0032]
The control 302 activates the filter 303, the difference calculation 304, the insertion position determination 305, and the insertion 306 for each still image in the moving image 307, and embeds the insertion information 310.
The filter 303 is the medical filter in the embodiment described above. The still images in the moving image 307 are read out one by one, the above-described filter processing is applied thereto, and the resulting filtered image 308 is stored in the memory.
In the difference calculation 304, a difference in luminance between one still image in the moving image 307 and the filter image 308 obtained from the still image is obtained for each pixel, and the result is stored in the memory as a changeable range 309. The changeable range 309 indicates a range of how much the luminance of each pixel of one still image in the moving image 307 can be changed.
The insertion point determination 305 divides a still image of 720 × 480 pixels into blocks of 8 × 8 pixels. As a result, 90 × 60 = 5400 blocks are obtained. With the above-described method, a block whose value is to be changed corresponding to the insertion information 310 is selected, and is set as an insertion block 311.
The insertion 306 changes the sum of the luminances of the blocks of the insertion block 311 so as to be the suction value 312 (n times the positive number A). As a result, one still image into which the information is inserted is obtained, and this is added to the watermarked moving image 313.
[0033]
FIG. 4 is a flowchart of the operation of the insertion 306. First, in step 401, the sum of the luminance of the target 8 × 8 pixel block 311 is calculated. Next, in step 402, an n-times multiple of 512, which is the closest to the sum of the luminances calculated in step 401, is set as the suction value.
Step 403 and subsequent steps are the actual insertion processing. First, in step 403, the luminance of each pixel in the target block is changed within the changeable range 309, and the sum of the luminance is also changed at the same time. In step 404, it is determined whether or not the sum of the changed luminances matches the suction value. If they match, the insertion operation is terminated. If not, the luminance value of the block is returned to the value before the change (that is, the block is watermarked). Is not inserted.) The insertion operation ends.
[0034]
FIG. 5 is a detailed flowchart of the insertion process. However, here, for simplicity, a case where the sum of the luminance values before the change is smaller than the suction value is considered. It is also assumed that the pixels in each block are represented by pixel numbers 1 to 64.
First, in step 501, the pixel number I is set to 1. Step 502 is a determination process for a pixel number I = 64. This will be described later. Step 503 determines whether R (I) is positive when the changeable range 309 of the pixel I is R (I). That is, it is determined whether the luminance can be added to the luminance value of the pixel I. If addition is not possible, I is incremented in step 507 and the process proceeds to the determination process in step 502. If addition is possible, the process proceeds to step 504 and subsequent steps.
[0035]
In step 504, the luminance value of the pixel I is added by one, and in step 505, the sum of the luminance values of the target block to which the pixel I belongs is added by one. In step 506, the value of the changeable range R (I) is reduced by 1 by adding the pixel I.
In step 404, if the sum of the brightness values is equal to the suction value in the above-described determination process, the process is terminated as watermark insertion into the target block. If not, the value of the pixel number I is incremented and the process proceeds to step 502.
Step 502 is a determination process for the pixel number I = 64, and there are two cases in which I = 64 is determined.
(1) A case where the addition process is performed once for a changeable pixel among the 64 pixels in the target block, but the brightness value can still be changed for some pixels.
In this case, since R (I) is not 0 at some pixels in step 508, the process proceeds to step 501, where the luminance value is added again.
(2) Of the 64 pixels in the target block, a plurality of addition processes are performed on pixels that can be changed. As a result, it is no longer possible to change the luminance value for all pixels before the sum of the luminance values reaches the suction value.
In this case, since R (I) = 0 for all the pixels in step 508, the process proceeds to step 405, in which the luminance value of each pixel is returned to the value before the change, and the process ends without performing the watermark insertion.
According to this embodiment, in a system that embeds information in a moving image by changing the luminance, it is possible to prevent image quality degradation and to at the same time endure the embedded information for the same reason as in the above embodiment.
[0036]
Next, a third embodiment of the present invention will be described with reference to FIGS.
This embodiment is a method of using more detailed parameters when inserting a watermark. For the type of image, the type of insertion information, and the like, the same expression method as in the second embodiment described above is used.
FIG. 6 is a functional configuration diagram of the third embodiment. Hereinafter, data 601 to 603, which are parameters at the time of inserting information, and an insertion process 604, which are different from the functional configuration diagram of FIG. 3, will be described.
The upper limit value 601 is a parameter that determines the upper limit of the changeable range 309, and does not allow the change of the luminance value equal to or more than the upper limit value in the insertion 306. The upper limit value 601 is used, for example, under the And condition with the changeable range 309 output from the filter 303, and is used when the upper limit of the changeable range is to be specified under another condition.
The offset value 602 sets an upper limit value at which the luminance value can be changed, and indicates an upper limit value when it is desired to change the brightness value beyond the changeable range 309 output by the filter 303.
The insertion possibility determination criterion 603 indicates a criterion used at the time of insertion other than the above. For example, by observing the variance value of the luminance of a block, the degree of flatness of the block can be determined, and a process of not inserting a watermark at a place where the image is too flat in the insertion 306 becomes possible.
[0037]
FIG. 7 is a flowchart of the operation of the insertion 604 in this embodiment. Processing other than steps 701 to 704 is the same as the processing in FIG.
In step 701, it is determined whether or not the variance of the luminance of the block is equal to or greater than the reference value as an insertion availability determination criterion. If it is equal to or more than the reference value, the process proceeds to steps 702 through steps 401 and 402.
In step 702, the luminance value of the pixel in the target block is changed within the range permitted by the filter. However, a change larger than the upper limit 601 is not allowed. If the luminance sum does not reach the suction value in step 404, the luminance of the pixel is changed again within the range of the offset value 602 in step 703, and the process proceeds to step 704.
In step 704, it is determined whether or not the sum of the changed luminance values has reached the suction value or the vicinity of the suction value (suction value ± 64). If the sum has reached, the watermark insertion is completed and the process ends. If it has not reached, the process proceeds to step 405, where the watermark is not inserted (the luminance value of the pixel is returned to the value before the change), and the process ends.
According to the methods shown in FIGS. 6 and 7, the method of changing luminance without image quality deterioration in the above embodiment can be further refined, so that the effect of preventing image quality deterioration is increased.
[0038]
By the way, in the case of a moving image, if the sum of the luminance of the selected block is made to match the adsorption value irrespective of the difference from the adsorption value (n multiple of 512), a sudden change in the luminance value may occur when the moving image is reproduced in real time. For example, the screen may flicker or the watermark position may be visually noticeable.
Therefore, a method of making the inserted information less noticeable will be described next with reference to FIG.
[0039]
FIG. 8 shows step 801 performed between steps 401 and 402 in the flowcharts of FIGS. The processing other than step 801 is the same as the processing in FIGS. 4 and 7 and will not be described.
In step 801, a block is determined according to a second upper limit value (not shown) of a difference between a luminance sum before a block change and a suction value, which is provided in advance, and it is determined whether to insert a watermark. Here, when the second upper limit value is set to 32, blocks whose luminance sums are not in the following range are actually targeted for watermark insertion. That is, when the luminance sum is in the following range, the difference from the original luminance sum increases when the watermark is inserted, and the watermark insertion is conspicuous, so that the watermark is not inserted.
N multiple of 512 + 256−32 <sum of luminance <n multiple of 512 + 256 + 32
In this equation, 512 is the positive number A described above, and 256 represents A / 2. The second upper limit is set from the input / output device 1101 and stored in the storage device 1103.
For blocks in the above range, the process ends without inserting a watermark.
According to this method, watermark insertion is not performed for a block having a large difference between the luminance sum and the suction value, so that when a moving image is reproduced in real time, the insertion information can be made less noticeable. Therefore, the effect of preventing image quality deterioration is further enhanced.
[0040]
Hereinafter, a fifth embodiment of the present invention will be described with reference to FIGS.
FIG. 9 is a schematic diagram of a watermark insertion block using the method of the present embodiment. Since the luminance value of the watermark insertion block 91 has changed due to the watermark insertion, the block may be conspicuous in a flat portion of the image or the like. As shown in FIG. 9, four regions 92 to 95 are created around the watermark insertion block, and the luminance value of the four regions is changed stepwise according to the luminance change of the block 91, so that the watermark block is conspicuous. Can be eliminated.
[0041]
FIG. 10 is a flowchart of a process of changing the luminance values of the areas 92 to 95. For the sake of simplicity, let us consider the change of the luminance values of the four 8 × 2 partial areas (A1, A2, A3, A4) 92 to 95 shown in FIG.
In step 1001, attention is paid to the block on the right of the watermark insertion block 91, and the amount of change in the luminance value of that portion is determined. In step 1002, the luminance value change amount calculated in step 1001 is multiplied by 0.8 and added to the luminance value of the A1 area 92. In step 1003, the luminance value change amount is similarly multiplied by 0.6 and added to the luminance value of the A2 area 93. In step 1004, the luminance value change amount is similarly multiplied by 0.4 and added to the luminance value of the A3 area 94. In step 1005, the brightness value change amount is multiplied by 0.2 and added to the brightness value of the A4 area 95, and the brightness value change process ends.
In this example, the area provided around the watermark insertion block 91 is generated by dividing one block into four. However, the present invention is not limited to this. Various modifications are possible, such as changing the luminance value.
[0042]
Further, in each of the above-described embodiments, the luminance of the pixel is changed as a method of embedding information. However, the present invention is not limited to this. This can be realized by changing the value of any one or any combination of the three primary colors, or any one or any combination of luminance and color difference, which constitutes each pixel.
The present invention can be applied to music other than images, for example, music. For example, a changeable range such as a loudness and a tone is obtained, and the change is made within the range. It is also possible to embed information by changing the volume, tone, and the like of each bar, and change the value little by little before and after the bar so that the bar is not noticeable.
It should be noted that the information embedded by the above-described method cannot be removed except for the method of embedding (position, pattern) or information for detection and removal. Conversely, those who know the embedding method and the information for detection and removal can extract the information embedded according to the present invention, and thus the present invention is suitable for managing the copyright information of the contents and the like.
[0043]
【The invention's effect】
According to the present invention, in embedding information in a content, the content can be changed as much as possible within a range where the content does not deteriorate, so that it is possible to prevent deterioration and to attain both the durability of the embedded information.
[Brief description of the drawings]
FIG. 1 is a functional configuration diagram of a first embodiment of the present invention.
FIG. 2 is a diagram showing a method for changing a luminance value of a pixel according to the first embodiment of the present invention.
FIG. 3 is a functional configuration diagram of a second embodiment of the present invention.
FIG. 4 is a flowchart of a watermark insertion process according to a second embodiment of the present invention.
FIG. 5 is a flowchart showing details of a watermark insertion process according to the second embodiment of the present invention.
FIG. 6 is a functional configuration diagram of a third embodiment of the present invention.
FIG. 7 is a flowchart of a watermark insertion process according to a third embodiment of the present invention.
FIG. 8 is a flowchart of a watermark insertion process according to a fourth embodiment of the present invention.
FIG. 9 is a schematic diagram of a watermark insertion block according to a fifth embodiment of the present invention.
FIG. 10 is a flowchart for changing a luminance value according to a fifth embodiment of the present invention.
FIG. 11 is a hardware configuration diagram according to a second embodiment of the present invention.
[Explanation of symbols]
101: input / output processing, 102: image data, 103: changeable range calculation processing, 104: changeable range data, 105: information embedding processing, 106: information insertion image data.

Claims (14)

An image processing method for changing a pixel value of a predetermined pixel included in an image including a plurality of pixels and inserting information into the image, comprising:
(1) performing a process of calculating a change in pixel value between the predetermined pixel and a plurality of pixels along one direction passing through the predetermined pixel in a plurality of directions passing through the predetermined pixel; Determining the direction of change,
(2) performing image processing along the obtained direction and obtaining a pixel value of the predetermined pixel after the image processing;
(3) obtaining a difference between a pixel value before the image processing and a pixel value after the image processing for the predetermined pixel, and setting a pixel value changeable amount when inserting the information;
An image processing method comprising: The image processing method according to claim 1, wherein
(4) setting a plurality of the predetermined pixels;
(5) for said predetermined pixel each set, executing the steps (1) to (3),
(6) the obtained in the step (5), for said predetermined pixel each, and the pixel value change amount capable, based on the value set in advance, the change amount of the pixel value of each predetermined pixel Defining steps,
An image processing method comprising: 3. The image processing method according to claim 2, wherein, for the predetermined pixel,
As the image processing of the step (2), the step of performing a smoothing process,
Determining the change amount of step (6), so that the smaller than the upper limit value set as the preset value,
An image processing method comprising at least one of the following. The image processing method according to claim 2, further comprising:
An operation is performed based on the amount of change to each of the predetermined pixels determined in the step (6), and a predetermined pixel value is calculated so that the calculation result becomes a value representing the information to be inserted and set in advance. Determining again the amount of change,
An image processing method comprising: 5. The image processing method according to claim 4 , wherein the calculation is an addition. The image processing method according to claim 1, wherein the pixel value is a luminance value. The image processing method according to claim 2, further comprising:
(7) for each bit constituting the insertion information a plurality of bits, performing the steps (4) to (6),
(8) changing a pixel value based on the determined change value,
(9) outputting the image whose pixel value has been changed,
An image processing method comprising: A storage medium storing a program for changing a pixel value of a predetermined pixel included in an image composed of a plurality of pixels and causing an electronic computer to execute image processing for inserting information into the image,
(1) performing a process of calculating a change in pixel value between the predetermined pixel and a plurality of pixels along one direction passing through the predetermined pixel in a plurality of directions passing through the predetermined pixel; Processing to determine the direction of change,
(2) performing image processing along the obtained direction, and obtaining a pixel value after the image processing for the predetermined pixel;
(3) processing for obtaining a difference between a pixel value before the image processing and a pixel value after the image processing for the predetermined pixel, and setting the pixel value changeable amount when inserting the information;
Storage medium storing a program for causing a computer to execute the program. A storage medium storing the program according to claim 8, wherein:
(4) a process of setting a plurality of the predetermined pixels,
(5) for said predetermined pixel each set, the process for executing the processing from (1) and (3),
(6) obtained by the process (5), for said predetermined pixel each, and the pixel value change amount capable, based on the value set in advance, the change amount of the pixel value of each predetermined pixel Processing,
Storage medium storing a program for causing a computer to execute the program. A storage medium storing the program according to claim 9, wherein:
A process of performing a smoothing process as the image process of the process (2);
A process of determining the change amount in the process (6) so as to be smaller than an upper limit set as the preset value;
A storage medium storing a program for causing a computer to execute at least one process of the above. A storage medium storing the program according to claim 9, further comprising:
An operation is performed based on the amount of change to each of the predetermined pixels determined by the process (6), and the operation result is a predetermined value of the predetermined pixel such that the result becomes a value representing the information to be inserted which is set in advance. Processing to determine the change amount again,
Storage medium storing a program for causing a computer to execute the program. A storage medium storing the program according to claim 11 , wherein:
A storage medium storing a program for causing an electronic computer to execute addition as the operation. A storage medium in which the program according to any one of claims 8 to 12 is stored,
A storage medium storing a program for causing a computer to execute a luminance value as the pixel value. A storage medium storing the program according to claim 9, wherein:
(7) for each bit constituting the insertion information a plurality of bits, the process for executing the processing from (4) (6),
(8) a process of changing the pixel value based on the determined change value,
(9) a process of outputting the image whose pixel value has been changed,
Storage medium storing a program for causing a computer to execute the program.

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