JP3476121B2 - Information detection device and information detection method - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an information detection device and an information detection device.
And an information detection method , and more particularly, to an information detection apparatus and an information detection apparatus for processing an image having additional information embedded in the image.
Regarding how to get out .

[0002]

2. Description of the Related Art There is a technique in which information to be added to specific image data (still image or moving image sequence) is added to the image data and the additional information is detected and used during reproduction. A typical example of this is the addition of copyright information.

When an unspecified user can use a specific image data, a person who has a copyright for the image can copy the copyright information in advance in order to claim the right. It is necessary to add it to the data. By adding copyright information, if the copyright information that should make the image data undisplayable is detected in the processing procedure of the image playback device or playback method, the image data is displayed. It is possible to take measures such as not having.

The above-mentioned addition or detection of copyright information is often used at present for preventing illegal copying of video tapes. Recently, there are many shops that rent video tapes, but if many users illegally copy a video tape borrowed from the shop and enjoy it, those who own the video tape and the video The store that rents tapes suffers a lot of damage.

Since image data is recorded on a video tape in an analog manner, the image quality is deteriorated when copying is performed. Therefore, when copying is repeated a plurality of times, it is very difficult to maintain the original image quality.

On the other hand, in devices which record and reproduce image data digitally, which are becoming popular recently,
The damage caused by illegal copying is even greater. This is because, in principle, a device that handles image data digitally does not deteriorate the image quality due to copying.
Therefore, illegal copy protection in a digitally processed device is far more important than in the case of an analog device.

There are mainly two methods for adding information to be added to image data to the image data.

The first method is a method of adding to the auxiliary portion of the image data. For example, in a video tape, as shown in FIG. 11, the auxiliary information of the image data is not substantially displayed on the display screen 1 (upper part of the screen) 2
It is recorded in. It is possible to add additional information using a part of this area.

The second method is a method of adding to the main part (substantially displayed part) of the image data. This is because, as shown in FIG. 12, a specific pattern (Water Mark pattern) (in FIG. 12, the image WM of the personal computer), the entire image or one of the images is not visually perceptible. It is added to the section. As a specific example of this, there is spread spectrum that adds or detects information by using a key pattern generated by using a random number or an M sequence.

An example of adding or detecting the additional information to the main part of the image data when the watermark pattern is used will be described below. This specific example is shown in FIGS.

It is assumed that for each pixel a watermark pattern corresponding to 4n × 4n pixels is used, as shown in FIG. 13, which takes either plus or minus two symbols. The watermark pattern preferably takes one of the two symbols at random, and its shape and size may be arbitrary.

When adding the additional information, an area having the same size as the area of the watermark pattern is set on the image to be added. The set area and the watermark pattern are compared with each other, and the value a is added to the pixel corresponding to the plus symbol, and the value b is subtracted from the pixel corresponding to the minus symbol. Both a and b may be arbitrary values, but they should be constant through the watermark pattern.

In the example of FIGS. 14 to 16, a = 1, b =
14, when all the pixel values of the area to be added are 100 as shown in FIG. 14, the pixel value is 101 in the positive area due to the embedding operation corresponding to the watermark pattern. And the pixel value in the negative region is.

When detecting the additional information, an area having the same size as the area of the watermark pattern is set on the image to be detected. The sum of all the pixel values in this area is used as the evaluation value. When summing all the pixel values, the set area and the watermark pattern are overlapped and collated, and addition is performed on pixels corresponding to a plus symbol and subtraction is applied to pixels corresponding to a minus symbol. In the example of FIG. 15, the pixel having the pixel value 101 is added to obtain the value 101 × 2n × 4n.
Is obtained, the pixel with the pixel value 99 is subtracted, and the value (−99
X2nx4n) is obtained, and the operation results thereof are added to obtain the value 2x2nx4n. At this time, the additional information cannot be correctly detected unless the same pattern as the watermark pattern used when adding the additional information is used. With such a detection operation, for example, as shown in FIG. 15, when the additional information is added, the evaluation value becomes (4n) ^ 2 (the same as the number of pixels included in the area), and FIG. As shown, the evaluation value when the additional information is not added is 0 (= 100 × 4n × 2n-100 × 4).
n × 2n).

When the area of the watermark pattern is sufficiently wide and the watermark pattern is sufficiently random, the evaluation value is always 0 when the additional information is not added. Therefore, when the evaluation value exceeds a certain threshold, it can be determined that the additional information is added. With the above procedure, 1-bit additional information can be added. To add more information, the entire image can be divided into k areas, and 2 ^ k (k bits) of information can be added by a processing method such as performing the above operations. .

As the watermark pattern, for example, one generated by using the M series can be used. The M sequence (longest code sequence) is a sequence consisting of binary symbols of 0 and 1, the statistical distribution of 0 and 1 is constant, the code correlation is 1 at the origin, and is inversely proportional to the code length in other cases. is there.
Of course, the watermark pattern may be generated by a method other than the M series.

By the way, an image is recorded as a digital signal,
When playing back, there is a lot of information as it is, so
Images are typically compressed. As a method for compressing images, JPEG (Joi
nt Photographic Experts Group), or MPEG (Moving Picture Experts Grou)
High-efficiency coding methods such as p) have been internationally standardized and have been put to practical use. Data compressed by these high-efficiency coding methods is called bitstream data, or simply bitstream. Further, as a contrasting expression, the image before compression and the image after decoding are referred to as a baseband image or simply baseband.

In either case, whether the baseband image to which the watermark pattern is added is distributed in the baseband as it is or is distributed as a bitstream after high efficiency encoding such as JPEG or MPEG. However, it would be convenient if the watermark pattern could be easily detected.

As a method of realizing this, the present applicant has
In Japanese Patent Application No. 9-252819, the watermark pattern DC (Direct Current) in the bit stream
We have proposed a method of adding so that it can be detected from the components. In this method, 8 × 8 pixel DCT (Discrete Cosine)
Transformation: Discrete cosine transform) A watermark pattern is added to a baseband image so that it is reflected in the DC component of a coded block such as a block. If the “pixel”, which is the unit of addition in the description of adding the watermark pattern above, is replaced with the “DC component of the encoded block”, the encoded block of the watermark pattern
It becomes possible to add to the DC component.

An image to which such a watermark pattern is added is distributed as it is as a baseband image,
The watermark pattern can be easily detected even when distributed as a bit stream that is highly efficient coded by MPEG or the like. That is, in the case of detection from a baseband image, the average value of pixel values is calculated for each area corresponding to the coded block, and the watermark pattern is detected by correlating the calculated average value and the watermark pattern. It In the case of detection from a bitstream, the bitstream is scanned, the value of the DC component for each coded block is decoded, and the watermark pattern is detected by correlating the value of the DC component with the watermark pattern.

In addition, in an encoding method such as MPEG2, there are two modes of DCT, frame mode and field mode.
Is used adaptively. FIG. 17 shows a block for performing frame DCT. When performing the frame DCT, FIG.
16 × 16 pixel macroblock 11 shown in FIG.
Is divided into 8 × 8 pixel frame mode blocks 12 to 15 in which the top fields and bottom fields shown in FIG. 17B are alternately arranged. On the other hand, when performing the field DCT, 1 shown in FIG.
The macroblock 11 of 6 × 16 pixels has field mode blocks 21 and 22 composed of a top field and field mode blocks 23 and 24 of 8 × 8 pixels composed of a bottom field shown in FIG. 18B. Will be divided.

As shown in FIGS. 17 and 18, the range of pixels occupied by the frame mode blocks 12 to 15 or the field mode blocks 21 to 24 is different. Therefore, 8 × 16, which is a combination of two DCT blocks vertically
A watermark pattern is added to the DC component of the pixel area as one unit. As a result, whether the DCT is performed in frame or field mode,
By decoding and averaging the DC components of the two blocks, the DC component of the 8 × 16 pixel area is calculated, and the watermark pattern can be detected.

By the way, as shown in FIG. 19, the aspect ratio (horizontal-to-vertical ratio of the image size) of an image is usually an image 26 of a video of the NTSC (National Television Systems Committee) system (see FIG. A)) is 4: 3, but the image 27 (Fig. 19 (B)) such as a movie is 1 horizontally long.
It is 6: 9. Since the aspect ratio differs between video and movies in this way, the following two methods are mainly used to record movie images on video.

In the first method, an image 27 such as a movie shown in FIG. 20 (A) is converted into an image 27 as shown in FIG. 20 (C).
In this method, the top and bottom of the video image are left and the image 27 is displayed in the central area 16: 9. The upper and lower parts are usually filled with black. This display method is called a letter box display, and the image is called a letter box image 29.

As a second method, as shown in FIG. 20 (B), the image 27 is reduced laterally by a factor of 3/4 and displayed on the entire area (4: 3 area) of the video image. Is. The video image 27 is laterally shrunk, this display method is referred to as squeeze display, and that image is referred to as the squeeze image 28.

The conversion from the squeeze image 28 to the letterbox image 29 is called letterbox conversion. The letterbox conversion is a conversion for reducing the squeeze image 28 by 3/4 in the vertical direction, as shown in FIGS. 20 (A) and 20 (B). The squeeze image 28 is contracted in the lateral direction, and the object represented on the image is represented thinner than it actually is. Therefore, when the image is viewed, the squeeze image 28 is subjected to this letterbox conversion. The letterbox image 29 has an advantage that it can be viewed as it is. On the other hand, the squeeze image 28 has an advantage that the image quality is good because the vertical resolution of the video image frame is effectively used. On the other hand, the letterbox image 29 is inferior in image quality to the squeeze image 28 because there are pixels that are not effectively used in the upper and lower portions.

The image of a movie is often recorded as a squeeze image 28 having a high image quality when recorded on a video. MPEG
When encoded with, for example, a squeeze image 28 created from a movie image can be encoded as it is as a squeeze image 28, or can be subjected to letterbox conversion so that it can be displayed and viewed as it is after decoding and the letterbox image 29. May be encoded as.

Here, the squeeze image 28 to which the watermark pattern is added and recorded is the squeeze image 2
It is easy to handle if the watermark pattern can be detected from the bit stream, whether it is encoded as 8, or after being subjected to letterbox conversion and then encoded as the letterbox image 29.

Conventionally, an encoding device 31 and a decoding device 32 utilizing the watermark pattern shown in FIG.
An unauthorized use prevention system has been realized. The baseband image, which is the letterbox image 29, is input to the encoding device 31. When it is not necessary to add the watermark pattern, the input baseband image is supplied to the encoding unit 44 via the switching unit 43.
When it is necessary to add a watermark pattern, the baseband image is displayed in the watermark pattern adding unit 41.
And the watermark pattern is added. When the letterbox conversion is not performed, the baseband image to which the watermark pattern is added is sent to the encoding unit 44 as it is via the switching unit 43. When letterbox-converted, the baseband image to which the watermark pattern is added is letterbox-converted by the letterbox converter 42, which is a vertical reduction filter, and supplied to the encoder 44 via the switcher 43. To be done. The encoding unit 44 encodes the input baseband image and outputs the obtained bitstream. The bit stream output from the encoding device 31 is supplied to the decoding device 32 via a predetermined transmission path.

The watermark pattern detector 52 of the decoding device 32 receives the bit stream output from the encoding device 31, detects information from the watermark pattern added to the image of the bit stream, and detects the detected information. The signal based on the above is output to the output control unit 51. The output control unit 51 supplies the encoding device 3 to the decoding unit 53 based on the signal from the watermark pattern detection unit 52.
Controls the supply of the bit stream supplied from 1.
The decoding unit 53 decodes the input bitstream,
Output a baseband image.

In the following, the processing performed in the unauthorized use prevention system, which is composed of the encoding device 31 and the decoding device 32, using the watermark pattern shown in FIG. 21 will be described in more detail.

As shown in FIG. 22A, the additional blocks 61-1 to 61-n in which the watermark pattern is added to the DC coefficient of the squeeze image 28 as shown in FIG. , 3/4 in the vertical direction in the letterbox image 29 after the letterbox conversion
Regions 62-1 to 62-n that are crushed in the area. for that reason,
The additional blocks of the letterbox image 29 are different from the additional blocks 61-1 to 61-n of the squeeze image 28, and the additional blocks 61-1 to 61-n of the squeeze image 28 are different.
The watermark pattern added to the DC coefficient is not directly reflected on the DC coefficient of the additional block of the letterbox image 29. Therefore, if the encoding is performed before the letterbox conversion, the watermark pattern for the squeeze image 28 capable of detecting the watermark pattern from the bitstream and the encoding after the letterbox conversion are performed. It has been considered to add both the watermark pattern for the letterbox image capable of detecting the watermark pattern to the baseband image.

The watermark pattern addition blocks 61-1 to 61-n for the squeeze image 28 are shown in FIG.
As shown in (A), it is an area of 8 × 16 pixels which is the same as the additional block of the normal watermark pattern. On the other hand, as shown in FIG. 23A, the additional blocks 71-1 to 71-n of the watermark pattern for the letterbox image 29 are 8 × 21.333 ... (= 16 × 4).
/ 3) Composed of pixels. Additional blocks 71-1 to 7
After 1-n is letterbox-converted, FIG.
8 × 16 pixel blocks 72-1 to 72-n.

The process performed by the conventional unauthorized use prevention system of FIG. 21 is a process of adding these two watermark patterns, and is a process of sequentially performing both the processes of FIGS. 24 and 25 . It should be noted that the order of addition processing may be either first.

FIG. 24 is a flow chart for explaining the process of adding a normal watermark pattern (for the squeeze image 28). First, in step S11, the watermark pattern adding section 41 sets a watermark pattern and sets addition amounts a and b. In step S12, the watermark pattern adding unit 41 reads one block of 8 × 16 pixels corresponding to a normal watermark pattern adding block. In step S13, the watermark pattern adding unit 41 determines whether the block is a block to which the watermark pattern should be added, and when it is determined that the block is a block to which the watermark pattern is to be added , And proceeds to step S14.

In step S14, the watermark pattern adding section 41 determines whether or not the read block is a block to be added, and when it is determined that the read block is a block to be added, step S14
In step 15, a is added to the DC value of the block, and the process proceeds to step S17. When it is determined in step S14 that the read block is a block from which the watermark is to be subtracted, the process proceeds to step S16, where the watermark pattern adding unit 41 subtracts b from the DC value of the read block, and then to step S17. move on. Step S1
In 7, the watermark pattern adding unit 41 determines whether or not the processing of all blocks has been completed. If it is determined that the processing of all blocks has not yet been completed, the process returns to step S12 and the processing is performed. continue.

If it is determined in step S13 that the block is not the block to which the watermark pattern is added, the process proceeds to step S17.

When it is determined in step S17 that all blocks have been processed, the watermark pattern adding section 41 ends the processing.

FIG. 25 is a flow chart for explaining the process of adding the watermark pattern for the letterbox image 29. In step S21, the watermark pattern adding unit 41 sets the watermark pattern for letterbox and adds the addition amounts a and b.
Set. In step S22, the watermark pattern addition unit 41 corresponds to the watermark pattern addition block for letterbox 8 × 21.33.
3 ... Read one block of pixels. Step S below
The procedure from 23 to step S27 is similar to that from step S13 to step S17, and the description thereof is omitted.

In the procedure shown in FIGS. 24 and 25, there are the following two methods for selecting a block to which a normal watermark pattern should be added and a block to which a watermark pattern for letterbox should be added. is there.

The first method is to add two watermark patterns to the DC component of another coded block spatially or temporally. For example, as a method of spatially adding to the DC component of another encoded block, a watermark pattern for the squeeze image 28 is added to the right half of the image and a watermark pattern for the letterbox image 29 is added to the left half of the image. There is a way to do it. As a method of adding to the DC component of another encoded block in terms of time, a watermark pattern for the squeeze image 28 is added to even-numbered frames and a letterbox image 29 is added to odd-numbered frames.
There is a method of adding a watermark pattern for each.

The second method is to add two watermark patterns to the same DC component both spatially and temporally. In this method, both watermark patterns are added to the entire area of the image, but it is necessary to use different watermark patterns for the squeeze image 28 and the letterbox image 29.

FIG. 26 is a flow chart for explaining the detection process. First, in step S31, the watermark pattern detection unit 52 sets the watermark pattern for the squeeze image 28 in W [x, y] and sets the watermark pattern for the letterbox image 29 in WL [x, y]. Set, evaluation value sum for detecting watermark pattern of squeeze image 28, and letterbox image 2
Evaluation value sumL for detecting 9 watermark patterns
Is initialized to 0, the threshold th for detecting the watermark pattern of the squeeze image 28 and the threshold thL for detecting the watermark pattern of the letterbox image 29 are set to thL.
To set. In step S32, the watermark pattern detection unit 52 simply decodes the bitstream and substitutes the DC component of the block of 8 × 16 pixels for I [x, y]. Here, I [x, y] is the DC component of the y-th block from the top and the x-th block from the left in the image. Step S33
At the watermark pattern detection unit 52,
I [x, y] × W [x, y] is added to sumL and I [x, y] × WL [x, y]
Is added. In step S34, the watermark pattern detection unit 52 determines whether or not processing has been performed for all I [x, y], and determines that processing has not been performed for all I [x, y]. If so, the procedure is step S
Returning to 33, the process is repeated.

If it is determined in step S34 that the process has been executed for all I [x, y], step S3
5, the watermark pattern detection unit 52
Is greater than th, and if sum is not greater than th, the process proceeds to step S36. In step S36, the watermark pattern detection unit 52
If it is determined whether or not sumL is larger than thL, and if it is determined that sumL is not larger than thL, the procedure proceeds to step S37, and the watermark pattern detection unit 52 determines that the watermark pattern is not added. The process is executed and the process ends.

If it is determined in step S35 that sum is greater than th, and in step S36,
When it is determined that sumL is larger than thL, the watermark pattern detection unit 52 executes the process when the watermark pattern is added in step S38, and ends the process.

It is not known which watermark pattern is contained in each block before the watermark pattern is detected. Therefore, it is necessary to correlate both watermark patterns with all blocks.

[0047]

The first conventional method is as follows.
The coding block for extracting the DC component used for detecting the watermark pattern is divided into two uses, that is, the coding block for detection from the letterbox image 29 and the coding block for detection from the squeeze image 28. Therefore, in order to make the detection and the detection time the same for only the letterbox image 29 (or the squeeze image 28), the number of DC components that can be used for the detection becomes half, and the detection accuracy deteriorates. On the contrary, in order to make the detection and the detection accuracy the same for only the letterbox image 29 (or the squeeze image 28), the number of DC components that can be used for the detection is separately secured in the letterbox image 29 and the squeeze image 28. This requires twice the detection time.

Further, in the second conventional method, since the two watermark pattern signals are added to the image in an overlapping manner, the watermark pattern pattern is likely to be seen as noise added to the original image, and the image quality is improved. to degrade.

The present invention has been made in view of such a situation, and it is possible to detect a watermark pattern without lowering the detection accuracy, increasing the detection time, degrading the image quality, or increasing the detection processing amount. To aim.

[0050]

An information detecting apparatus according to claim 1 converts a watermark pattern in correspondence with resolution conversion or image frame conversion, and encodes in an image subjected to resolution conversion or image frame conversion. Block and resolution conversion
Or between the watermark pattern that has been converted into a picture frame
An arithmetic means for generating an evaluation value by performing a product-sum operation of mutually corresponding parts, and a determination means for comparing the evaluation value with a predetermined threshold value and determining whether or not a watermark is added are provided. The arithmetic means corresponds to the evaluation value when the number of pixels associated with the converted watermark pattern and the coded block in the image subjected to the resolution conversion or the image frame conversion is smaller than a predetermined ratio. Na
It is characterized in that the calculation of the watermark pattern of the other part is omitted.

In the information detecting method according to the third aspect, the watermark pattern is converted in correspondence with the resolution conversion or the image frame conversion, and the encoding block and the resolution conversion or the image in the image subjected to the resolution conversion or the image frame conversion are converted. Frame conversion
Correspondence with the watermark pattern
An evaluation value is generated by performing a product-sum operation of the parts, and the evaluation value is compared with a predetermined threshold value to determine whether or not a watermark is added, and when the evaluation value is calculated, it is converted. When the number of pixels associated with the watermark pattern and the coded block in the resolution-converted or frame-converted image is smaller than a predetermined ratio,
It is characterized in that the calculation of the watermark pattern of the portion not corresponding to the evaluation value is omitted.

[0052]

In the information detecting device according to the first aspect and the information detecting method according to the third aspect, the watermark pattern is converted in accordance with the resolution conversion or the image frame conversion, and the resolution conversion or the image frame conversion is performed. Of the parts corresponding to each other between the encoded block and the water mark pattern whose resolution has been converted or whose frame has been converted in the captured image.
An evaluation value is generated by performing a sum operation, and it is determined whether or not a watermark is added by comparing the evaluation value with a predetermined threshold value. When the evaluation value is calculated, the converted watermark pattern And the coding block in the image whose resolution has been converted or whose frame has been converted .
When the number of pixels to be displayed is smaller than a predetermined ratio, the calculation of the watermark pattern of the portion that does not correspond to the evaluation value is omitted.

[0054]

[0055]

[0056]

BEST MODE FOR CARRYING OUT THE INVENTION Below, DC of frames and fields
Assuming MPEG2 in which T is adaptively used, description will be made using a block of 8 × 16 pixels as a block for adding or detecting a watermark pattern.

The configuration of the unauthorized use prevention system of the present invention is as follows:
The configuration is similar to that of the unauthorized use prevention system shown in FIG.

FIG. 1 is a diagram showing a case where the squeeze image 28 is reduced in the vertical direction during letterbox conversion, and then the upper portion of the screen is clogged and the margin is left only at the lower portion. Figure 1 (A)
Is an additional block 81 of 8 × 16 pixels (x in the horizontal direction) for adding a watermark pattern in the squeeze image 28.
And the y-th block in the vertical direction).
When the squeeze image 28 including the additional block 81 is letterbox converted (multiplied by 3/4 in the vertical direction), the additional block 81 is an additional block 82 of 8 × 12 pixels on the letterbox image 29 shown in FIG. Becomes Also, FIG.
(C) is a coding block 83-1 to 83-of 8 × 16 pixels when the letterbox image 29 is coded.
It is a figure which shows 3. Note that y'in the figure represents an integer.

FIG. 2 is a diagram when the squeeze image 28 is vertically reduced and the margins are taken at the top and bottom of the screen during letterbox conversion. FIG. 2A is a diagram showing an additional block 81 of 8 × 16 pixels for adding a watermark pattern in the squeeze image 28. When the squeeze image 28 including the block 81 is subjected to letterbox conversion, the additional block 81 becomes an 8 × 12 pixel additional block 82 on the letterbox image 29 shown in FIG. 2B. Also, FIG. 2C is a diagram showing coding blocks 83-1 to 83-3 of 8 × 16 pixels when the letterbox image 29 is coded.

The method of detecting the watermark pattern in the case of FIG. 1 will be described below with reference to FIG. Figure 3
Shows a row of one vertical additional block 81 extracted from the image shown in FIG. Figure 3
(A) shows additional blocks 81-1 to 81-4 to which the watermark pattern in the squeeze image 28 is added, and the additional blocks 81-1 are divided every 8 × 16 pixels.
Symbols of the watermark pattern are assigned to the DC components 81 to 81-4, respectively. W [x, y] is the coordinate x, y of the watermark pattern (the coordinate of the block, the x coordinate is the integer part when divided by the x coordinate of the pixel, and its y coordinate is the y of the pixel). These are represented by the integer part when the coordinate is divided by 16, and each symbol represents the symbol. Coordinates start from 0 in both the vertical and horizontal directions, with the origin at the upper left of the screen. For example, the symbol of the watermark pattern corresponding to the 8 × 16 pixel block on the upper left of the screen is W
[0,0], and the symbol of the watermark pattern corresponding to the block below it is W [0,1].

When the squeeze image 28 is letterbox converted, the vertical resolution becomes 3/4. Therefore,
The watermark addition block 81 in the squeeze image 28 in (A) or FIG. 2A is the 8 × 12 pixel watermark addition block 8 shown in FIG. 3B.
2-1 to 82-4 (the y coordinate of the block is the integer part when the y coordinate of the pixel is divided by 12).

When the letterbox image 29 is encoded,
Two DCTs in the frame mode or two DCTs in the field mode for every 8 × 16 pixels of the letterbox image 29.
It is performed once (since DCT is performed every 8 × 8 pixels, respectively). Now, let us say that the average value of the DC coefficients of the two DCTs of the coding blocks 83-1 to 83-3 shown in FIG. 3C is represented by I [x, y]. That is, I [x, y] is
It is assumed that the DC value of the DCT coefficient at the coordinate x, y portion of the block of every 8 × 16 pixels is represented.

In this example, between the additional blocks 82-1 to 82-4 shown in FIG. 3B and the coding blocks 83-1 to 83-3 shown in FIG. 3C, The parts corresponding to each other are subjected to sum-of-products operation to detect the watermark pattern. That is, the components of the watermark pattern are calculated by the following equation (1).

Sum = Σ (I [x, 0] × W [x, 0]) + Σ (I [x, 0] × W [x, 1]) + Σ (I [x, 1] × W [x, 1]) ＋ Σ (I [x, 1] × W [x, 2]) ＋ Σ (I [x, 2] × W [x, 2]) ＋ Σ (I [x, 2] × W [x, 3] ) (1) In the above equation, Σ means the sum of products operation for all x.

Of the pixels included in the coding block 83-1, 12/16 of all pixels are the watermark symbol W.
As a result of being affected by [x, 0] and affecting all 4/16 pixels by the watermark symbol W [x, 1],
If the DC component value I0 [x, y] of the squeeze image 28 is changed to I [x, y], I [x, 0] is I [x, 0] = I0 [x, 0] +12 / 16 x W [x, 0] + 4/16 x W [x,
1] can be expressed. Therefore, the first term in equation (1) is
It can be transformed like.

Σ (I [x, 0] × W [x, 0]) = Σ ((I0 [x, 0] + 12/16 × W [x, 0] + 4/16 × W [x, 1]) × W [x, 0]) ≒ Σ ((12/16 × W [x, 0] + 4/16 × W [x, 1]) × W [x, 0]) ≒ Σ (12/16 × W [ x, 0] × W [x, 0]) = 3/4 Σ (W [x, 0] × W [x, 0]) (2)

Σ ((12/16 × W [x, 0] + 4/16 × W [x, 1]) × W [x,
0]) is based on the fact that ΣI0 [x, 0] × W [x, 0] ≈ 0 holds, that is, the DC component of the image and the watermark generally have no correlation. is there. Also, Σ (12/16
× W [x, 0] × W [x, 0]) is transformed into ΣW [x, 1] × W [x, 0] ≈ 0,
That is, the watermark is based on the fact that the watermark does not correlate with the watermark whose phase is shifted.

Similarly, the other terms of the equation (1) can be transformed into the equation (3).

Sum = Σ (I [x, 0] * W [x, 0]) + Σ (I [x, 0] * W [x, 1]) + Σ (I [x, 1] * W [x, 1]) ＋ Σ (I [x, 1] ＊ W [x, 2]) ＋ Σ (I [x, 2] ＊ W [x, 2]) ＋ Σ (I [x, 2] ＊ W [x, 3] ) ≈ 3 / 4Σ (W [x, 0] * W [x, 0]) + 1 / 4Σ (W [x, 1] * W [x, 1]) + 1 / 2Σ (W [x, 1] * W [x, 1]) + 1 / 2Σ (W [x, 2] * W [x, 2]) + 1 / 4Σ (W [x, 2] * W [x, 2]) + 3 / 4Σ (W [x, 3] * W [x, 3]) = 3 / 4Σ (W [x, 0] * W [x, 0]) + 3 / 4Σ (W [x, 1] * W [x, 1]) + 3 / 4Σ (W [x, 2] * W [x, 2]) + 3 / 4Σ (W [x, 3] * W [x, 3]) (3)

As described above, the evaluation value of the added watermark pattern is determined by each of the coding blocks 83-1 to 83-3.
-3, its DC component and its coding block 83
-1 to 83-3 are obtained by taking the products of the symbols of the watermark pattern added to at least a part of -1 to 83-3 and summing them (performing the sum of products operation). The evaluation value of the watermark is reduced to 3/4 because it is vertically reduced to 3/4 by the letterbox conversion.

Next, the calculation of the watermark evaluation value in the case of FIG. 2, that is, when the letterbox conversion is performed to vertically reduce the size to 3/4 and then margins are provided above and below the screen will be described. . As shown in FIG. 2 (B),
The number of pixels in the margin at the top of the screen is y0. Figure 4 (A)
Is a watermark addition block 82 in the letterbox image 29. FIG. 4B is a diagram showing the pixels 91 of one vertical column extracted from the additional block 82.

The y-coordinate of one vertical column of pixels 91 included in one additional block 82 of the letterbox image 29 is y0.
The range is from + 12y to y0 + 12y + 11. FIG. 4C is a diagram showing pixels in the range of the coding blocks 83-1 to 83-3 when coding as the letterbox image 29. In the pixel 91 of one column in the vertical direction, since the encoding blocks 83-1 to 83-3 are composed of 8 × 16 pixels, the encoding blocks 83-1 to 83-which differ every 16 pixels in the vertical direction.
Included in 3. Therefore, for example, y coordinate (pixel coordinate)
Is y0 + 12y, the y coordinate (block coordinate) is (y0 +
12y) // 16 included in the coding block 83. Also, for a pixel whose y coordinate is y0 + 12y + 11, the y coordinate is (y0 + 12y + 11) //
It is included in 16 coding blocks 83. here,
Represents division with fractions truncated.

The size of the coding block 83 is 1 in the vertical direction.
Although it has a spread of 6 pixels, the pixels of the additional block to which the watermark symbol W [x, y] of the same value is added are only 12 pixels in the vertical direction, so y
The pixels of the additional block whose coordinates are between y0 + 12y and y0 + 12y + 11 are the coding blocks 83 whose y coordinates are (y0 + 12y) // 16, or whose y coordinates are (y0 + 12y + 11) / / 16 in the coding block 83. Therefore, the DC component of the coding block 83 which should be correlated with W [x, y] is (y0 + 12y) // 16 = (y0 + 12y + 11) //
If 16 (1 additional block corresponds to 1 coded block), then I [x, (y0 + 12y) // 16] only,
If (y0 + 12y) // 16 ≠ (y0 + 12y + 11) // 16 (one additional block corresponds to two coded blocks), then I
They are [x, (y0 + 12y) // 16] and I [x, (y0 + 12y + 11) // 16].

Next, the process of adding the watermark pattern and the process of detection will be described. 24 and 25
In the conventional example shown in the flowchart of FIG. 1, two different watermarks for the squeeze image 28 and the letterbox image 29 are added, whereas the present invention is simplified in that only one watermark is added. However, it is also simplified that it is not necessary to determine which watermark is added.

FIG. 5 is a flow chart for explaining the process of adding the watermark pattern. Step S41
At, the watermark pattern adding section 41 sets the watermark pattern and also sets the addition amounts a and b. In step S42, the watermark pattern adding unit 41 sets a block of 8 × 16 pixels corresponding to a normal watermark pattern adding block to 1 block.
Read one. In step S43, the watermark pattern adding unit 41 determines that the read block is the watermark.
It is determined whether or not the block is a block to which a mark is added. If it is determined that the read block is a block to which a watermark is added, the process proceeds to step S44, a is added to the DC value of the block, and the process proceeds to step S46. move on.

When it is determined in step S43 that the read block is a block for which the watermark is to be subtracted, the process proceeds to step S45, in which the watermark pattern adding section 41 subtracts b from the DC value of the read block, It proceeds to step S46. In step S46, the watermark pattern adding unit 41 determines whether or not the processing of all blocks has been completed. If it is determined that the processing of all blocks has not yet been completed, the process returns to step S42 to perform the processing. To continue.

When it is determined in step S46 that all blocks have been processed, the watermark pattern adding section 41 ends the processing.

FIG. 6 is a flow chart for explaining the watermark detection processing. First, in step S51, the watermark pattern detection unit 52 sets the watermark pattern to W [x, y], and evaluates sum for detecting the watermark pattern of the squeeze image 28 and the letterbox image 29. The evaluation value sumL for detecting the watermark pattern is initialized to 0 and
A threshold th for detecting the watermark pattern of the squeeze image 28 and a threshold thL for detecting the watermark pattern of the letterbox image 29 are set. Step S52
At, the watermark pattern detection unit 52 simply decodes the bit stream to obtain a block of 8 × 16 pixels.
Substitute the DC component into I [x, y]. In step S53, the watermark pattern detection unit 52 detects the first (x,
Select (0,0) as a set of y), add I [x, y] × W [x, y] to sum, and add I [x, (y0 + 12y) // 16] × W to sumL. Add [x, y].
Now, assuming that y0 = 0, this results in I [x, 0] in FIG.
× W [x, 0] is calculated.

In step S54, the watermark pattern detection unit 52 changes (y0 + 12y) // 16 from (y0 + 12y + 11) // 1.
It is judged whether it is equal to 6 and (y0 + 12y) // 16 becomes (y0 + 12y + 11)
If it is determined that it is not equal to // 16 (that is, if one additional block 82 corresponds to two encoded blocks), the process proceeds to step S55, and sumL is set to I [x, (y0 + 12y + 11 ) /
/ 16] × W [x, y] is added, and the process proceeds to step S56.

In step S54, (y0 + 12y) // 16 becomes
If it is determined to be equal to (y0 + 12y + 11) // 16 (that is, one additional block 82 corresponds to one encoded block), the process proceeds to step S56.

In step S56, the watermark pattern detection unit 52 determines whether or not the processing has been executed for all the sets, and if it is determined that there is an unprocessed set, the procedure is step S53. Return to and repeat the subsequent processing. In the case of the example in FIG. 3, step S5
In step 4, since the values of the left and right terms of the equation are both 0, a YES determination is made, and y = 1 is set in step S56 (the increment processing of x is omitted here),
In step S53, I [x, 0] × W [x, 1] is added to sumL (the description of the process of sum is also omitted here). In step S54, the value of the left term of the equation becomes 0 and the value of the right term becomes 1, so that a NO determination is made, and in step S55, I [x, 1]
× W [x, 1] is added to sumL

If it is determined in step S56 that the processing has been executed for all the (x, y) pairs, the process proceeds to step S57, in which the watermark pattern detecting section 52
It is determined whether sum is larger than th, and if it is determined that sum is not larger than th, the process proceeds to step S58. In step S58, the watermark pattern detection unit 52
Determines whether sumL is greater than thL. If it is determined that sumL is not greater than thL, the procedure is step S5.
9, the watermark pattern detection unit 52 executes the process when the watermark pattern is not added, and ends the process.

If it is determined in step S57 that sum is greater than th, and in step S58,
When it is determined that sumL is larger than thL, the watermark pattern detection unit 52 executes the process when the watermark pattern is added, and ends the process.

As described above, according to the present invention, only one watermark is added to the squeeze image 28 so that the squeeze image and the letterbox image can be used as the water marker.
It is possible to detect the click. Therefore, it is not necessary to add two watermarks to the DC component of another coded block spatially or temporally. In the present invention, the coding block 83 for extracting the DC component used to detect the watermark is the coding block 83 for detection from the letterbox image 29 and the coding block 83 for detection from the squeeze image 28. It is not necessary to divide it into two of 83,
There is almost no decrease in detection accuracy and increase in detection time. Furthermore, since it is not necessary to add two watermarks to the same DC component, the image quality does not deteriorate.

The processing can be further simplified by adding the parameter k to the algorithm shown in FIG. An algorithm using this parameter k will be described with reference to FIG.

The processing step of FIG. 7 is step S6.
Except for step 1, step S63, step S64, and step S65, the processing content is the same as the step having the same last digit of the number in the flowchart of FIG. 6, and the description thereof will be omitted. Will be described only. In step S61, the watermark pattern detection unit 52 adds k in addition to the process of step S51.
Set the parameters. In step S63, the watermark pattern detection unit 52 adds I [x, y] × W [x, to sum.
y] is added, and I [x, (y0 + 12y + k) // 16] × W [x, y] is added to sumL.

In step S64, the watermark pattern detection unit 52 determines that (y0 + 12y + k) // 16 is (y0 + 12y + 11-).
(y0 + 12y + k) // 16 is (y0 + 12y + k) // 16
12y + 11-k) // 16 is determined not to be equal (that is, one additional block 82 corresponds to two coding blocks 8
(If it corresponds to 3), the process proceeds to step S65, and I is added to sumL.
[x, (y0 + 12y + 11-k) // 16] × W [x, y] is added, and step S
Proceed to 66.

In step S64, (y0 + 12y + k) // 16
When it is determined that is equal to (y0 + 12y + 11-k) // 16 (that is, one additional block 82 corresponds to one coding block), the process proceeds to step S66.

In this algorithm, for example, when k = 2 is set, the coding block 83 to which the pixel to be compared belongs
Is calculated by equation (4) and equation (5). (y0 + 12y + k) // 16 = (16i + 15) // 16 = i (4) (y0 + 12y + 11-k) // 16 = ( 16 (i + 1) +6) // 16 = i + 1 (5)

In this case, y shown in FIG.
What is used to correlate with the additional block whose coordinate is y is the DC component of the coding block 83 whose y coordinate is i, which is shown by the diagonal line rising to the right in FIG. The y-coordinate indicated by the diagonal line to the lower right of C) becomes the DC component of the encoding block 83 of i + 1.

When k = 3 is set, the coding block 83 to which the pixel to be compared belongs is calculated by the equations (6) and (7). (y0 + 12y + k) // 16 = 16 (i + 1) // 16 = i + 1 (6) (y0 + 12y + 11-k) // 16 = (16 (i + 1) +5) // 16 = i + 1 (7)

That is, in this case, what is used to correlate with the additional block whose y coordinate is y is shown in FIG.
The y-coordinate indicated by the diagonal line rising to the right of is only the DC component of the coded block of i + 1.
The component is no longer used for calculating the correlation value.

FIG. 9 shows additional blocks 82-1 to 82-4 and an encoding block 83-1 when k = 3 is set.
It is a figure explaining the sum-of-products calculation between 83-4. In this example, the coding blocks 83-1 to 83-4 are
One pixel is shifted upward with respect to the additional blocks 82-1 to 82-4. Sum-of-products operation I [x, 0] × W [x, for the portion where the additional block 82-2 and the encoding block 83-1 overlap
1] is omitted. Similarly, the sum of products operation for the portion where the additional block 82-4 and the encoding block 83-4 overlap
I [x, 3] × W [x, 3] is also omitted.

Similarly, when k is another value, the additional block 82 whose y coordinate is y (the additional block in FIG. 8B) and the coding block 83 whose y coordinate is i (FIG. 8).
The correlation with the DC component of the (C) encoding block to which the pixels 16i + 12 to 16i + 15 belong) is obtained when k is 2 or less. In the example of FIG. 8, the additional block 8 whose y coordinate is y
2 and the number of corresponding (overlapping) pixels in the encoding block 83 whose y coordinate is i is 3 pixels (16i + 13,16i + 14,16i + 1).
5). In other words, when the number of pixels corresponding to the pixels of the additional block 82 and the pixels of the encoding block 83 is less than or equal to the value of the parameter k, the pixels are regarded as not corresponding (not overlapping), and the correlation is obtained. Made not to be used for.

The watermark component is included only in the pixels of the coding block 83 which overlap with the additional block. When the k parameter is used, k /
If only 16 or less pixels have a watermark component, by not performing the correlation calculation, the process of calculating the correlation can be omitted for the part where the watermark component is less likely to be detected. Therefore, it is possible to reduce the amount of processing without changing the calculated correlation value.

For example, if k = 6 is set, the correlation is calculated only when more than half of the additional block 82 corresponds to the coding block 83.

As described above, the process using the k parameter omits the process of calculating the correlation with respect to the portion in which the watermark component is less likely to be detected, and reduces the amount of processing without changing the calculated correlation value. Can be reduced.

FIG. 10 is a flow chart for explaining a process for detecting a watermark component in which the normalization process is added to the process shown in the flow chart of FIG. This processing is to multiply the detected value by k / 16 when the watermark component is included only in the pixel of the ratio of k / 16 in the encoding block 83. The processing steps of FIG. 10 have the same processing contents as the steps having the same last digit of the numbers in the flowchart of FIG. 6 except for steps S73 and S75, and the description thereof will be omitted.
Only the parts different from the processing of FIG. 6 will be described below.

In step S73, the watermark pattern detection unit 52 adds I [x, y] × W [x, y] to sum and I [x, (y0 + 12y) // 16] × to sumL. W [x, y] × NOTMAX (12,16-
Add (y0 + 12y)% 16) / 16. In step S75, the watermark pattern detection unit 52 sets I to sumL.
[x, (y0 + 12y + 11) // 16] × W [x, y] × ((y0 + 12y + 11)% 16 + 1) / 1
Add 6 Note that NOTMAX (A, B) represents the lesser of A and B, and% represents the remainder when division is performed.

As described above, in the processing of FIG. 10, the evaluation value of the watermark obtained by calculating the correlation between the watermark and the DC component is corrected by the ratio of the overlap between the coding block 83 and the additional block. Enables more reliable detection. Also, letterbox image 2
Each value added when obtaining the evaluation value sumL for 9 must be 1
Since it is divided by 6, if the threshold is set to 16 times in advance, the operation of dividing by 16 is unnecessary.

As is clear from FIG. 4, the pixel ratio of the coding block 83 corresponding to a certain additional block 82 is a value between 1/16 and 12/16 of the coding block 83. The component of the watermark that can be extracted when correlation is obtained when the ratio of the pixels of the coding block 83 corresponding to the additional block 82 is 1/16 and 12/16 of the coding block 83. There is a 12-fold difference in the amount of. Therefore, the ratio of the pixels of the coding block 83 corresponding to the additional block 82 is equal to that of the coding block 83.
When it is 1/16, the influence of noise becomes large and the judgment becomes difficult. Therefore, in this processing example, the additional block 82
The value of the pixel of the coding block 83 corresponding to is multiplied by the value obtained by the correlation with the coding block 83.
As a result, it is possible to correct that the reliability of the watermark component varies depending on the ratio of the pixels of the encoded block corresponding to the additional block.

In the above description, the size of the coding block and the size of the additional block 83 in the squeeze image are 8 × 16 pixels, but other numbers of pixels may be used.
For example, to make the block size 4 × 16 pixels,
When adding a watermark to an image, addition processing is performed for each area of 4 × 16 pixels instead of 8 × 16 pixels, and when detecting a watermark of an image, in addition to DC, the lowest order is applied only in the horizontal direction. AC (Alternating Cu
rrent: AC coefficient (coefficient on the right side of the DC component, 8 ×
The watermark can be detected by decoding (corresponding to the difference between the average values of the right half and the left half of the block of 16 pixels).

In order to make the block size 8 × 8 pixels, the watermark is added to each 8 × 8 pixel area. At the time of detection, for the block of the DCT in the field mode, in addition to DC, the AC coefficient of the lowest order only in the vertical direction (the coefficient located below the DC coefficient, the average of the upper half and lower half of the block) (Corresponding to the difference between the values) is decoded to obtain the DC value in the range of 8 × 8 pixels. 8 for frame mode DCT block
Since there is a DC value for each region of × 8 pixels, no special processing is required.

The unit for adding the watermark (size of additional block) is such that the watermark can be detected even if the conventional letterbox conversion is performed.
The unit is the same as when adding a watermark for the squeeze image 28. Therefore, an image to which a watermark has been added by a method in which the watermark can be detected even if the conventional letterbox conversion is performed can be detected by the image processing apparatus and method of the present invention and is compatible.

Therefore, in the image to which the watermark has been added by the conventional method and the letterbox conversion has been performed,
There is an advantage that it is not necessary to add the watermark again.

Watermark symbols are +1, -1
Any symbol other than the above may be used. Further, instead of two types, three or more types of symbols may be used. For example, when three types of symbols of +1, 0, and -1 are used and the symbol is 0 when the pattern is compared with the watermark pattern, the evaluation value sum is not affected (the pixel value is evaluated. You can give any meaning to each symbol, such as adding or subtracting to the value sum).

The area to which the watermark pattern is added on the image may have any shape and range. Further, the shape and range of the area for which the evaluation value is obtained at the time of detection may be arbitrary as long as they match the added watermark pattern. Further, addition or detection may be performed using information in a wide range spatially or temporally. That is, the correlation with the front and back or the left and right in the frame may be used, or the frames preceding and succeeding in time may be used.

In the present specification, the system means
It represents the entire device composed of a plurality of devices.

As a providing medium for providing the user with the computer program for performing the above-described processing,
In addition to recording media such as magnetic disks, CD-ROMs, and solid-state memories, communication media such as networks and satellites can be used.

[0110]

According to the information detecting apparatus and the information detecting method of the third aspect, the watermark pattern is converted in accordance with the resolution conversion or the image frame conversion, and the resolution conversion or the image conversion is performed. Sum of products of parts corresponding to each other between the encoded block in the frame-converted image and the water mark pattern subjected to the resolution conversion or the image frame conversion.
By performing the calculation, the evaluation value is generated , it is determined whether or not the watermark is added by comparing the evaluation value with a predetermined threshold value, and when the evaluation value is calculated, the converted watermark pattern and , corresponding attached the coded blocks in the resolution conversion or image frame converted image
When the number of pixels to be processed is smaller than a predetermined ratio, the calculation of the watermark pattern of the part that does not correspond to the evaluation value is omitted, so that the detection accuracy decreases, the detection time increases, the image quality deteriorates, or the detection The watermark pattern can be detected without increasing the throughput.

[Brief description of drawings]

FIG. 1 is a diagram illustrating a letterbox-converted image.

FIG. 2 is a diagram illustrating a letterbox-converted image.

FIG. 3 is a diagram illustrating the relationship between additional blocks and coding blocks.

FIG. 4 is a diagram illustrating a relationship between pixels of an additional block and a coding block.

FIG. 5 is a flowchart illustrating a process of adding a watermark pattern.

FIG. 6 is a flowchart illustrating a watermark detection process.

FIG. 7 is a flowchart illustrating a watermark detection process.

FIG. 8 is a diagram illustrating a relationship between pixels of an additional block and a coding block.

FIG. 9 is a diagram illustrating the relationship between additional blocks and coding blocks.

FIG. 10 is a flowchart illustrating a watermark detection process.

FIG. 11 is a diagram illustrating additional information to an image.

FIG. 12 is a diagram illustrating additional information added to an image.

FIG. 13 is a diagram illustrating a watermark pattern.

FIG. 14 is a diagram illustrating addition of a watermark pattern.

FIG. 15 is a diagram illustrating detection of a watermark pattern.

FIG. 16 is a diagram illustrating detection of a watermark pattern.

FIG. 17 is a diagram illustrating an image coding range.

FIG. 18 is a diagram illustrating an image coding range.

FIG. 19 is a diagram illustrating an aspect ratio of an image.

FIG. 20 is a diagram illustrating conversion of an image aspect ratio.

FIG. 21 is a diagram illustrating a configuration example of a conventional unauthorized use prevention system.

FIG. 22 is a diagram illustrating additional blocks of a watermark pattern.

FIG. 23 is a diagram illustrating additional blocks of a watermark pattern.

FIG. 24 is a flowchart illustrating a conventional process of adding a watermark pattern.

FIG. 25 is a flowchart illustrating a conventional watermark pattern detection process.

FIG. 26 is a flowchart illustrating a conventional watermark pattern detection process.

[Explanation of symbols]

28 squeeze images, 29 letterbox images,
41 Watermark pattern addition unit, 52 Watermark pattern detection unit, 81 Additional block, 8
2 additional blocks, 83 encoded blocks

Continuation of front page (56) References Japanese Patent Laid-Open No. 10-191017 (JP, A) Walter Bender, Daniel Gruhl, Norishige Morimoto, Anthony Lu, Data Hiding Technology Supporting Digital Watermarks (above), Nikkei Electronics, Japan, February 24, 1997, No. 683, p. 149-162 (58) Fields surveyed (Int.Cl. ⁷ , DB name) H04N ^7/ 00-7/088 H04N 1/38-1/393 JISST file (JOIS)

Claims (3)

(57) [Claims] 1. A watermark pattern is collated with an image for each small area consisting of M × N (M and N are positive integers) pixels of a part of an image, and the watermark pattern is obtained. based on relative embedded image information as a watermark, from the image constituted by applying resolution conversion or image frame conversion, the resolution conversion or image frame conversion of
In the information detecting device for detecting the converted information, the watermark pattern is converted in correspondence with the resolution conversion or the image frame conversion, and the encoding block and the resolution in the image subjected to the resolution conversion or the image frame conversion.
With the converted or image frame converted watermark pattern
By performing the product-sum operation of the parts corresponding to each other between
Ri, a calculating means for generating an evaluation value, and a determination means for determining whether it is added watermark by comparing the evaluation value with a predetermined threshold value, said calculating means is the conversion If the number of pixels associated with the watermark pattern and the coded block in the resolution-converted or frame-converted image is smaller than a predetermined ratio, the portion that does not correspond to the evaluation value
An information detecting device characterized in that the calculation of the watermark pattern is omitted. In the information detection apparatus according to claim 1, wherein the calculating means, corresponding with are pixels of said converted watermark pattern, the coded blocks in said resolution conversion or image frame converted image The ratio of
An information detection device characterized by multiplying the evaluation value . 3. A watermark pattern is collated with an image for each small area consisting of a part of the image, which is M × N = M × N (M and N are positive integers), and the watermark pattern is obtained. based on relative embedded image information as a watermark, from the image constituted by applying resolution conversion or image frame conversion, the resolution conversion or image frame conversion of
In the information detecting method for detecting information that has been converted, the watermark pattern is converted in correspondence with the resolution conversion or the image frame conversion, and the encoding block and the resolution in the resolution-converted or image frame-converted image.
With the converted or image frame converted watermark pattern
By performing the product-sum operation of the parts corresponding to each other between
By generating an evaluation value, it is determined whether or not a watermark is added by comparing the evaluation value with a predetermined threshold value, and when the evaluation value is calculated, the converted watermark pattern, Pixels associated with the coding block in the resolution-converted or frame-converted image
Corresponds to the evaluation value when the number is smaller than a certain percentage
An information detecting method, characterized in that the calculation of the watermark pattern of the non- existing portion is omitted.