JP2000216984A - Image processing system, image transmission system and recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid impairment of design properties of an image from which a visible electronic watermark is eliminated by arbitrarily eliminating a visible electronic watermark from an image that specifies the right information containing the visible electronic watermark. SOLUTION: An image 212 is divided into eight sheets of bit planes 63-1 to 63-8, and a visible electronic watermark is inserted into an area A of the plane 63-1. The pixel value of the area A of the plane 63-1 is compared with the pixel value of an image 201 of the visible electronic watermark that corresponds to the pixel value of the area A. If no matching is confirmed between both pixel value, the former pixel value is corrected for the letter one, At the same time, the pixels of the image 121 are corrected so as to have little change in the corrected pixel value. Such comparing and correcting operations are applied to all pixels of the area A of the image 121. Thus, an image 122 is obtained. Then only an area A of the bit plane of the image 122 is shifted in the higher order direction, to obtain an image 131 eliminated of visible electronic watermark. As a result, the capacity can be reduced, when the images containing the visible electronic watermarks are accumulated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an image processing system using a visible digital watermark, an image transmission system, and a recording medium on which a program is recorded.

[0002]

2. Description of the Related Art Recently, when a digital image is transmitted on the Internet or the like, right information or the like may be inserted into the image. For example, in the displayed image, information indicating the copyright holder of the image or the like is inserted. Digital watermarking techniques for inserting rights information and the like into images include visible digital watermarks that are visible and invisible digital watermarks that are invisible. Of these, the visible digital watermark can clearly indicate the right information, but impairs the design of the original image. Therefore, based on the information of the visible digital watermark at the time of insertion, the visible digital watermark is removed as necessary.

[Problems to be solved by the invention]

When an image is stored or transmitted over a network, the data is often compressed due to the large data capacity of the image. There is a JPEG method or the like as a still image data compression technique. JPEG halves still images
Although it can be compressed to about 0, it is said that when the compressed data is expanded, information may be lost compared to the original image. A compression method that does not return to the data before compression when decompressed is called lossy compression.

[0004] When the image containing the visible digital watermark thus reversibly compressed is decompressed again, if the information of the original image of the visible digital watermark is lacking, the visible digital watermark may not be completely removed by the conventional method. is there.

The present invention has been made in view of such a problem, and an object of the present invention is to arbitrarily remove a visible digital watermark from an image subjected to lossy compression, thereby maintaining the design of the image. Such an image processing system, and an image transmission system that transmits an image with a visible digital watermark inserted on a network and can remove the visible digital watermark when necessary.
And a recording medium on which the program is recorded.

[0006]

In order to achieve the above-mentioned object, the present invention comprises means for dividing a first image into bit planes, and a method for dividing a first image into a predetermined area of a bit plane having a plurality of divided bit planes. Means for writing a binary image to generate a second image; and compressing the second image to generate a third image.
Means for generating a fourth image by expanding the third image, generating means for generating a fourth image, and an image of a predetermined area of a bit plane on which a binary image of the fourth image is written. And a correction unit for correcting a value of a predetermined area of the bit plane of the fourth image if the result of the comparison does not match. An image processing system.

A second aspect of the present invention is an image transmission system for transmitting an image between a server and a client, wherein the server transmits an image in which a visible digital watermark has been inserted and information for removing the visible digital watermark to the client. And a client for displaying an image obtained by removing the visible digital watermark from the image using the visible digital watermark removal information only when displaying the image on a display.

A third aspect of the present invention is an image transmission system for transmitting an image between a server and a client, wherein the server transmits an image in which a visible digital watermark is inserted and visible digital watermark removal information to the client. Holding the image in which the visible digital watermark is inserted and the visible digital watermark removal information, and displaying an image in which the visible digital watermark is removed from the image using the visible digital watermark removal information only when displaying the image on a display. An image transmission system comprising:

According to a fourth aspect of the present invention, a first image is divided into bit planes, and a binary image is written in a predetermined area of a bit plane having a plurality of divided bit planes to generate a second image. Means for compressing the second image to generate a third image; means for expanding the third image to generate a fourth image; Comparing means for comparing an image in a predetermined area of the bit plane in which the image is written with the original binary image; and a value in the predetermined area of the bit plane of the fourth image when the result of the comparison does not match. As a correction means to correct
This is a recording medium that records a program that causes a computer to function.

[0010]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a diagram showing a schematic configuration of an image transmission system 1 according to the present embodiment.

In FIG. 1, a server computer 3 and a client computer 7 are connected via a network. The server computer 3 stores the image, and the client computer 7 uses the image 111 stored in the server computer 3 via the network.

The server computer 3 has an auxiliary storage device 5
Is connected. The auxiliary storage device 5 holds an image 111 containing a visible digital watermark and information 13 for removing the visible digital watermark.

FIG. 2 is a diagram showing the accumulation of images in the server computer 3. The server computer 3 performs a visible digital watermark insertion process on the original image 101 as described later, generates an image 111 with the visible digital watermark and information 13 for removing the visible digital watermark, and stores them in the auxiliary storage device 5. The visible digital watermark removal information 13 is data relating to the region and position where the visible digital watermark is inserted, the image of the visible digital watermark, and the like.

An auxiliary storage device 15 is connected to the client computer 7 shown in FIG. 1, receives an image 111 with a visible digital watermark via a network, and stores it in the auxiliary storage device 15. The client permitted to use the original image 101 has a CD on which a removal processing application program 17 for removing a visible digital watermark is recorded.
The ROM 9 is distributed and the image 111 can be used by using the removal processing application program 17;

FIGS. 3 and 4 are diagrams for explaining the transmission of image data to the client computer 7. FIG. As shown in FIG. 3, the image 11 stored in the auxiliary storage device 5 on the server side.
1 and the information 13 for removing the visible digital watermark are sent to the client computer 7 via the network and stored in the auxiliary storage device 15.

The client computer 7 performs the removal processing of the visible digital watermark using the removal processing application program 17, and the image 1 from which the visible digital watermark has been removed.
31 is displayed on the screen.

FIG. 4 is a diagram showing transmission of image data when the client computer 7 does not have the auxiliary storage device 5. In this case, the client computer 7 keeps accessing the server computer 3 via the network, and removes the image 111 and the visible digital watermark removal information 1.
3 and performs the process of removing the visible digital watermark in the same manner as in FIG.
Is displayed on the screen.

3 and 4, the client computer 7 authenticates the user by inputting a password or the like, and for a legitimate user, performs a visible digital watermark removal process to display the image 131, and displays the image 131. Alternatively, the image 131 may be displayed to the user without performing the visible digital watermark removal processing.

As described above, in the embodiment shown in FIG. 3 and FIG.
11 is inserted into the server computer 3 by using an unauthorized access means.
Prevents the image 111 from being used without losing the contents of the original image.

Further, by transmitting the image 111 with the visible digital watermark inserted, even if a third party illegally accesses the data being transmitted and takes out the image 111, the contents of the original image are not damaged. Prevents the image 111 from being used.

In the client computer 7,
By displaying the image after performing the visible digital watermark removal processing on the image data, the image can be browsed without deteriorating the contents of the original image.

Since the client computer 7 does not accumulate the image from which the visible digital watermark has been removed, the image data is printed out or the image data is copied without damaging the contents of the original image. Hinder.

For example, when a digital image is sold to a specific member over a network, client software for removing the visible digital watermark and displaying the image is sold only to the member, and the non-member can view the visible digital watermark. A method of using such that the image in the removed state cannot be seen can be considered. It is also conceivable to sell digital images in a form in which an image with a visible digital watermark inserted is distributed as a sample image, and information for removing the visible digital watermark is sold to customers for a fee.

In the embodiment shown in FIGS. 3 and 4, when transmitting an image from the server computer 3 to the client computer 7, the image may be compressed or transmitted as it is.

Next, a process for inserting a visible digital watermark into the original image 101 and a process for removing the visible digital watermark from the image 111 containing the visible digital watermark will be described. FIG.
Is a flowchart showing the sequence of this series of operations.
Here, in the original image 101, a visible digital watermark is inserted into the area A, and is not inserted into the area B.

The original image 101 is divided into bit planes (step 301), and a bit shift process is performed on the area A (step 302). The area A of the most significant bit plane is replaced with the visible digital watermark image 201 (step 303), and the visible digital watermark is inserted. The image into which the visible digital watermark is inserted is compressed by the irreversible compression method (step 304).

Next, the compressed image is expanded (step 305). Divide the expanded image into bit planes,
The pixel value of each pixel of the area 201 of the most significant bit plane and the image 201 is compared (step 306). Here, the pixel value of the image 201 is obtained from the visible digital watermark removal information 13.

In step 306, if the pixel value of the area 201 of the most significant bit plane is equal to the pixel value of the image 201, a bit shift process is performed on the pixel (step 308). In step 306, when the pixel value of the area A of the most significant bit plane is not equal to the pixel value of the image 201, the pixel value of the most significant bit plane is corrected to the value of the image 201 (step 307), and the pixel is bit-shifted Processing is performed (step 308). Thus, the visible digital watermark is removed from the image.

Of the processing shown in FIG. 5, steps 301 to 303 are processing for inserting a visible digital watermark, and steps 306 to 308 are processing for removing the visible digital watermark. Visible watermark insertion,
A series of removal operations is performed by the server computer 3 shown in FIG.
May be performed only by the server computer 3, or when the processing is performed via a network as described above, the insertion processing may be performed by the server computer 3 and the removal processing may be performed by the client computer 7.

Next, the visible digital watermark insertion processing will be described in detail. FIG. 6 is a diagram illustrating a bit shift process of a bit plane when a visible digital watermark is inserted. Original image 1
When 01 is represented by a pixel value of 8 bits, that is, an image of 256 gradations, the original image 101 is divided into eight bit planes 60-1,..., 60-8.

The bit plane 60-1 is the most significant bit plane, and the bit plane 60-8 is the least significant bit plane. Here, if the value of a certain pixel is X, X = a1 * 128 + a2 * 64 + a3 * 32 + a4 × 1
6 + a5 * 8 + a6 * 4 + a7 * 2 + a8 * 1 a1 to a8 are represented by "0" or "1". The most significant bit plane 601-1 is a1
, The bit plane 601-2 indicates the value of a2, and similarly, each bit plane indicates the value of a3, a4,....

As shown in FIG. 6, the bit values of the pixels in the area A of the eight bit planes 60-1, 60-2,..., 60-8 are shifted one bit at a time in the lower direction. At this time, the contents of the least significant bit of the area A are discarded, but there is no problem because the change of the least significant bit has little effect on the image quality.

Next, the bit value of the pixel in the area A of the most significant bit plane 61-1 is represented by the binary image 2 of the visible digital watermark.
01 and an image 111 is obtained. That is, the visible digital watermark is inserted into the image 111.

FIG. 7 is a diagram showing bit values of one pixel in the area A and the area B in the visible digital watermark insertion processing. A bit 71-1 shown in FIG. 7 is a value of a certain pixel in an area A of the bit plane 60-1 of the image 101.
The bit value is “1”. Similarly, bits 71-2, 71
-3,..., 71-8 are the bit planes 60 of the image 101
, 60-3,..., 60-8 are the same pixel values,
The bit values are "0", "1", ..., "0".

As shown in FIG. 7, in the image 101, the values of the bits 71-1 to 71-7 are shifted downward. That is, bits 72-2 to 72 of the image 102
The value of bit 71-1 to bit 71-7 enters -8,
The contents of bits 71-8 are discarded. At this time, in FIG. 5, "0" is inserted in the bit 72-1.
May be.

Next, the value of the bit 72-1 is replaced with a visible digital watermark pattern, that is, "0" which is the value of the corresponding pixel of the image 201. Thus, an image 111 into which the visible digital watermark has been inserted is obtained.

On the other hand, since the bit shift processing is not performed on the pixels in the area B, the value does not change. Here, the area A
The position and size of the region B, the pixel value of the image 201, and the like are stored as the visible digital watermark removal information 13. FIG.
, The least significant bit 91 of the area B is replaced with “0”, the least significant bit of the area A is replaced with “1”,
The determination of the area may be performed.

As described above, the image 111 into which the visible digital watermark is inserted is subjected to irreversible compression with little influence on the image quality, and is further expanded to obtain the image 121. The process of removing the visible digital watermark from the decompressed image 121 will be described in detail below.

FIG. 8 is a diagram showing a bit plane bit shift process at the time of the visible digital watermark removal process. Image 1
21 is divided into eight bit planes 63-1,..., 63-8.

A visible digital watermark is inserted in the area A of the bit plane 63-1. Bit plane 63-1
Are compared with the pixel values of the corresponding pixels of the image 201 of the visible digital watermark, and if the values do not match, the pixel values of the region A of the bit plane 63-1 are replaced with the pixel values of the image 201 And the pixels of the image 121 are corrected so that the change in pixel value due to the correction is small.

Such comparison and correction are performed for all pixels in the area A of the image 121, and an image 122 is obtained.
Only the area A of the bit plane of the image 122 is shifted upward, and an image 131 is obtained. The image 131 is an image obtained by removing the visible digital watermark from the image 111.

Next, a method of correcting a pixel value in the area A will be described. FIG. 9 is a diagram illustrating a bit shift process for the pixel a in the region A, and FIG. 10 is a diagram illustrating a bit shift process for the pixel b in the region A.

As shown in FIG. 9, the pixel value “1” of the most significant bit 75-1 of the pixel a of the image 121 matches the pixel value “1” of the pixel a of the image 201 of the visible digital watermark. In this case, the value of the bit is not modified, and the value of bit 75-2 to bit 75-8 is shifted upward.

As shown in FIG. 10, pixel b of image 121
Does not match the pixel value “0” of the pixel b of the image 201 of the visible digital watermark. In this case, the value of the bit 77-1 is corrected to the pixel value “0” of the pixel b of the image 201, and the values of the bits 77-2 to 77-8 are the pixel values before the correction. Is modified to be closest to For example, as shown in FIG. 10, the pixel value of the image 121 before correction is “10000”.
010 ”, the pixel value of the corrected image 122 is“ 0 ”.
1111111 ".

That is, if the image 121 has 8 bits and 256 gradations, when the value of the most significant bit in the image 121 is corrected from “1” to “0”, the value is the value closest to the pixel value of the image 121. Let “127” be the pixel value of the image 122. This is expressed in binary notation as "0111111
1 ".

When modifying the value of the most significant bit from “0” to “1” in the image 121, “128” which is the value closest to the pixel value of the image 121 is set as the pixel value of the image 122. This is expressed in binary notation, "100000
00 ”.

As described above, according to the present embodiment, the image 121 containing the visible digital watermark which has been
, Any visible digital watermark can be removed. Therefore, the right information can be clearly indicated on the image, and the watermark can be arbitrarily removed, so that the design of the image is not spoiled. Further, the capacity can be reduced when storing an image with a visible digital watermark, and the transmission time can be shortened even when transmitting an image over a network.

When an image is used on a network, only a compressed image with a visible digital watermark is distributed on the network, and the visible electron elimination application program 17 is distributed to an authorized client, so that illegal images can be obtained. Use can be prevented.

In this embodiment, the watermark is inserted by replacing the area A of the most significant bit plane with the image 201 of the digital watermark, but the visible digital watermark can be inserted into any bit plane. In this case, only the bit plane into which the visible digital watermark is inserted and the lower bit planes need to be subjected to the bit shift.

When removing the visible digital watermark, the bit plane into which the visible digital watermark has been inserted is compared with the image 201 of the visible digital watermark. To the bit values of the image 201, and all lower bit values
The bit value of 01 may be reversed.

Since the visible digital watermark becomes less noticeable as the bit plane into which the visible digital watermark is inserted becomes lower, the bit plane can be selected according to the required visual digital watermark appearance.

The present embodiment is not limited to the case where the gradation of the image is 8 bits, and is applicable to a gray scale image and a color image. For example, in a color image displayed in the RGB color space, a red visible digital watermark is inserted by performing the processing shown in FIG. 4 on the R plane.

Next, a more effective second embodiment for maintaining the design of an image will be described.

The present embodiment is applied to a color image. By extracting a luminance image from the color image and inserting a visible digital watermark into the luminance image in the same manner as described above, the influence on the hue is reduced. In addition, the design of the image is maintained.

FIG. 11 is a flowchart of the visible digital watermark insertion processing, and FIG. 12 is a schematic diagram showing an outline of the insertion processing.

As shown in FIG. 12, an image 1111 is obtained by inserting a visible digital watermark image 201 into an original image 1101.
And the area where the image 201 is to be inserted is the area A,
A region where no insertion is made is referred to as a region B.

The original image 1101 is subjected to color space conversion (step 1201), and is converted into a color space including luminance information and other information to obtain an image 301. In the image 301, an image composed of a luminance plane is referred to as an image 1401, and an image indicating other information is referred to as an image 1501. Here, original image 1
If the image 101 is originally an image in a color space including luminance information, the processing in step 1201 is not necessary, and the original image 11
The image 1401 may be the luminance plane 01.

Next, a bit shift process is performed on the area A of the image 1401 composed of the luminance plane of the image 301 (step 1202) to obtain an image 1402. Image 14
02, a region A is a binary image 201 of a visible digital watermark.
And insert a watermark (step 120
3).

The inverse conversion of the color space is performed from the image 1411 with the visible digital watermark thus created and the image 1501 of the plane other than the luminance (step 24) to obtain an image 1111 with the visible digital watermark inserted.

Hereinafter, each step of FIG. 2 will be described in more detail. Step 1201 If the original image 1101 is an image expressed in the RGB color space, each pixel value is converted by the following equation, and converted into a color space YPbPr, YIQ, or the like including luminance information and other information. Here, the case of converting to the color space YPbPr will be described. In the color space YPbPr, Y is a luminance signal, and Pb and Pr are color difference signals.

Y = 0.121R + 0.701G + 0.087B Pb = −0.116R−0.384G + 0.500B (1) Pr = 0.500R−0.445G−0.055B Thus, the original image 1101 is converted to the color space YPbPr. Image 1401 of the luminance plane
, And the Pb plane and the Pr plane become the image 1501.

Steps 1202 and 1203 As for the bit shift processing, the same processing as that shown in FIGS. 6 and 7 is performed, except that the luminance plane is processed, and a visible digital watermark is inserted into the luminance plane image 1401. .

Step 1204 The color space is converted from the image 1411 and the image 1501 created in this way, and an image 1111 with a visible digital watermark expressed in the same color space as the original image 1101 is obtained. For example, conversion from the YPbPr color space to the RGB color space is performed by the following equation.

R = 1.576Pr + Y B = 1.826Pb + Y (2) G = (Y−0.087B−0.212R) /0.701

The watermarked image 11 thus created
11, the luminance information of the area A changes when compared with the original image 1101, but if the color space conversion is reversible,
Since no change occurs in the components other than the luminance, the region A does not impair the hue of the original image 1101. Further, if the error at the time of color space conversion cannot be discriminated by the naked eye, the influence on the hue can be neglected.

Further, by inserting a watermark into the luminance plane using the bit shift process, the magnitude relationship between the bit planes is maintained, the digital watermark is inserted translucently, and the effect on the image is small.

It is assumed that the image 1111 thus created is irreversibly compressed and decompressed to obtain an image 1211. Hereinafter, an operation procedure for removing the visible digital watermark from the image 1211 will be described. FIG. 13 is an explanatory diagram of the removing operation.

The color space conversion of the watermarked image 1211 is performed. Since the image 1211 is expressed in the RGB color space, it is converted into the image 311 expressed in the YPbPr color space by the equation (1). The image 311 is divided into an image 1411 of a luminance plane and an image 1511 of other information.

Next, as in the above-described embodiment, the area A of the luminance plane image 1411 of the image 311 is compared with the binary image 201, and if they do not match, the pixel value is corrected. To perform bit shift processing to
21 is obtained.

The color space is inversely transformed from the image 1421 and the image 1511 to obtain the image 12 without the visible digital watermark.
22 is obtained. For example, when converting to the original RGB color space, equation (2) is used. As described above, in the present embodiment, it is possible to write a watermark on a luminance plane, perform irreversible compression, and further remove the watermark.

[0071]

As described above, according to the present invention, a visible digital watermark can be arbitrarily removed from an image subjected to lossy compression, and the design of the image is maintained. Also, transmitting the image with the visible digital watermark inserted on the network,
When necessary, the right information can be specified without deteriorating the design of the image from which the visible digital watermark can be removed.

[Brief description of the drawings]

FIG. 1 is a diagram showing an image transmission system 1 according to an embodiment of the present invention.

FIG. 2 is a diagram showing image storage in a server computer 3;

FIG. 3 is an explanatory diagram of transmission of image data to a client computer 7;

FIG. 4 is an explanatory diagram of transmission of image data to a client computer 7;

FIG. 5 is a flowchart showing a process of inserting and removing a visible digital watermark;

FIG. 6 is a diagram illustrating a process of inserting a visible digital watermark.

FIG. 7 is a diagram illustrating a process of inserting a visible digital watermark.

FIG. 8 is an explanatory diagram of a visible digital watermark removal process.

FIG. 9 is an explanatory diagram of visible digital watermark removal processing.

FIG. 10 is an explanatory diagram of visible digital watermark removal processing.

FIG. 11 is a flowchart illustrating a process of inserting a visible digital watermark according to another embodiment.

FIG. 12 is a diagram illustrating a process of inserting a visible digital watermark.

FIG. 13 is an explanatory diagram of visible digital watermark removal processing.

[Explanation of symbols]

 1. Image transmission system 3. Server computer 7. Client computer

Continued on the front page F term (reference) 5B057 AA11 CB16 CB18 CC04 CE08 CG03 DC22 5C076 AA03 AA14 BA03 BA04 BA05 BA06 BA09

Claims (6)

[Claims] 1. A means for dividing a first image into bit planes; a means for writing a binary image in a predetermined area of a bit plane having a plurality of divided bit planes to generate a second image; Means for compressing the second image to generate a third image; means for expanding the third image to generate a fourth image; and a binary image of the fourth image written therein. Comparing means for comparing the image of the predetermined area of the bit plane with the original binary image, and correcting the value of the predetermined area of the bit plane of the fourth image if the result of the comparison does not match. Means, and an image processing system comprising: 2. The method according to claim 1, wherein the correcting unit is configured to change a value of a predetermined area of a bit plane of the fourth image into a second area.
2. The image processing system according to claim 1, wherein the correction is performed so as to be close to the value of the image and to reduce a change in pixel value due to the correction. 3. The image processing system according to claim 1, wherein the first image is an image of a luminance plane obtained by color space conversion of an original image. 4. An image transmission system for transmitting an image between a server and a client, the server transmitting an image with a visible digital watermark inserted therein and information for removing the visible digital watermark to a client, and a display on a display. And a client that displays an image obtained by removing the visible digital watermark from the image using the visible digital watermark removal information only when the image transmission is performed. 5. An image transmission system for transmitting an image between a server and a client, the server transmitting an image with a visible digital watermark inserted therein and information for removing the visible digital watermark to the client, A client that holds an image in which a watermark has been inserted and information for removing a visible digital watermark, and displays an image in which the visible digital watermark has been removed from the image using the visible digital watermark removing information only when displaying the image on a display. An image transmission system comprising: 6. A means for dividing a first image into bit planes, a means for writing a binary image in a predetermined area of a bit plane having a plurality of divided bit planes, and generating a second image; Means for compressing the second image to generate a third image; means for expanding the third image to generate a fourth image; and a binary image of the fourth image written therein. Comparing means for comparing the image of the predetermined area of the bit plane with the original binary image, and correcting the value of the predetermined area of the bit plane of the fourth image if the result of the comparison does not match. As means, a recording medium that records a program that causes a computer to function.