CN114547563A - Image watermark embedding method and system capable of adaptively adjusting embedding strength - Google Patents

Abstract

The invention particularly relates to a picture watermark embedding method capable of adaptively adjusting embedding strength, which comprises the following steps: s100, coding is carried out according to the random module R and the binaryzation information to be embedded to obtain a binaryzation watermark pattern; s200, horizontally and longitudinally tiling the watermark pattern to the width and height of the picture to be embedded to obtain a watermark matrix image; s300, modifying three-channel parameter values of each pixel point of the picture to be embedded according to the content of the watermark matrix image in the RGB color space, wherein the modification amplitude is in inverse proportion to the gray value of the pixel point. During superposition, the embedding of the watermark is conveniently realized by modifying the pixel values of RGB three channels, and during modification, the modification amplitude is in inverse proportion to the gray value, namely the modification amplitude is small under a light color background and large under a dark color background, so that the self-adaptive modification of the modification amplitude is realized, the invisible effect of the watermark is improved, and the watermark is not easy to perceive.

Description

Image watermark embedding method and system capable of adaptively adjusting embedding strength

technical field

The invention relates to the technical field of watermark embedding, in particular to a picture watermark embedding method and system capable of adaptively adjusting the embedding strength.

Background technique

Copyrighted images are a concept relative to pirated images. Usually refers to the copyright holder of the picture, or the author or organization that created the picture, and authorizes the image work that can be used for commercial, publishing, exhibition and other purposes. After the picture is created, the owner of the picture will generally add a watermark to the picture to avoid being stolen. At present, there are two common picture watermarking technologies.

The first is the visible watermark, that is, adding visible information or icons to the picture. This method is relatively simple and fast. The disadvantage is that it is visually visible and easy to be attacked and erased, and the customer's experience of viewing the picture is poor. The second is invisible watermarking. The mainstream image invisible watermarking algorithm in the market mainly converts the image from the spatial domain to the frequency domain, then embeds the watermark in the frequency domain, and then restores it to the spatial domain. The invisible watermark is invisible and difficult to achieve. It has many advantages such as perceptibility and easy erasure, which is obviously better than visible watermark.

There are many schemes for adding invisible watermarks to pictures. The invention patent "Watermark Generation and Decoding Method, Storage Medium and Electronic Equipment" (application number: 2021107265874) submitted by our company on June 29, 2021 discloses a method of adding invisible watermarks to images. The method of adding a watermark, here a watermark pattern is generated by random template R and copyright information, and then the watermark pattern is superimposed on the image to be embedded. Since the watermark is embedded by slightly modifying the channel value, the superimposed image has very little change compared with the original image, so it has a better invisible effect. However, since the above modifications are all fixed values, the visibility of the watermark is different under different shades of background. The light background is slightly more obvious than the watermark in the dark background. For example, when there are a lot of blank areas in the picture, The watermark will be more obvious.

SUMMARY OF THE INVENTION

The primary purpose of the present invention is to provide a picture watermark embedding method that can adaptively adjust the embedding strength, so as to ensure the consistent visual effect of the watermark under light or dark backgrounds.

In order to achieve the above purpose, the technical scheme adopted in the present invention is: a picture watermark embedding method that can adaptively adjust the embedding strength, comprising the following steps: S100, encoding according to the random module R and the binarized information to be embedded, and obtaining two Valued watermark pattern; S200, tile the watermark pattern horizontally and vertically to the width and height of the picture to be embedded, to obtain a watermark matrix diagram; S300, in the RGB color space, according to the content of the watermark matrix diagram, to be embedded in the picture each time The three-channel parameter value of each pixel is modified, and the modification magnitude is inversely proportional to the gray value of the pixel.

Another object of the present invention is to provide a picture watermark embedding system that can adaptively adjust the embedding strength, so as to ensure the consistent visual effect of the watermark under light or dark backgrounds.

In order to achieve the above purpose, the technical scheme adopted in the present invention is: a picture watermark embedding system that can adaptively adjust the embedding strength, including a watermark pattern generation module, which is used for encoding according to the random module R and the binarized information to be embedded. The binarized watermark pattern; the watermark matrix generation module is used to generate a watermark matrix map with the same size as the image to be embedded according to the watermark pattern; the watermark overlay module is used to generate the watermark matrix map according to the gray value of the pixels in the image to be embedded and the watermark matrix map 2. Modifying the three-channel parameter value of each pixel with a preset modification range to obtain a watermark-embedded picture, where the modification range is inversely proportional to the gray value of the pixel.

Compared with the prior art, the above two solutions of the present invention have the following technical effects: generating a watermark pattern according to the random template R and the information to be embedded, and then generating a watermark matrix diagram according to the watermark pattern, which can conveniently obtain the same size as the picture to be embedded. When the watermark image is superimposed, it is convenient to embed the watermark by modifying the pixel values of the RGB three channels, and when modifying, the modification amplitude is inversely proportional to the gray value, that is, the modification amplitude is small under the light background, Under the dark background, the modification range is large, which realizes the adaptive modification of the modification range, improves the invisible effect of the watermark, and is not easy to be detected.

Description of drawings

Fig. 1 is the flow chart of the present invention;

Fig. 2 is the watermark pattern generation flow chart in the present invention;

Figure 3 is a system block diagram of the present invention.

Detailed ways

The present invention will be described in further detail below with reference to FIGS. 1 to 3 .

Referring to FIG. 1 , the present invention discloses a picture watermark embedding method that can adaptively adjust the embedding strength, including the following steps: S100 , encoding according to the random module R and the binarized information to be embedded to obtain a binarized watermark pattern S200, the watermark pattern is tiled horizontally and vertically to the width and height of the picture to be embedded, to obtain a watermark matrix diagram; S300, in the RGB color space, according to the content of the watermark matrix diagram, each pixel point three channels of the embedded picture are treated The parameter value is modified, and the modification magnitude is inversely proportional to the gray value of the pixel. Generate a watermark pattern according to the random template R and the information to be embedded, and then generate a watermark matrix image according to the watermark pattern, which can easily obtain a watermark image of the same size as the image to be embedded. When superimposing, modify the pixel values of the RGB three channels to It is convenient to embed the watermark, and when modifying, let the modification range be inversely proportional to the gray value, that is, the modification range is small under the light background, and the modification range is large under the dark background, so that the adaptive modification of the modification range is realized. , which improves the invisible effect of the watermark and is not easy to be detected.

It should be pointed out that the "modification amplitude is inversely proportional to the gray value of the pixel" mentioned here does not mean that for any two pixels P1 and P2, if the gray value of P1 is greater than the gray value of P2, then P1 The modification range must be smaller than the gray value of P2. This sentence should be understood as follows: when the gray value is small, the modification range is large; when the gray value is large, the modification range is small.

，其中R、G、B和r、g、b分别代表修改前后的像素点三通道参数值，这里通过定义RGB三通道变化最大的那个值为修改幅度，这样就能更好的计算其余灰度值的关系；像素点的灰度值

，修改前后像素点的灰度值变化小于设定阈值，这个阈值可以设置为0.1左右，这样可以保证修改前后，像素点的灰度值基本不变。Further, in the step S300, modify the amplitude

, where R, G, B and r, g, and b represent the three-channel parameter values of the pixels before and after the modification, respectively. Here, by defining the value with the largest change in the RGB three-channel value as the modification range, the rest of the gray levels can be better calculated. The relationship between the values; the gray value of the pixel point

, the change of the gray value of the pixel before and after the modification is less than the set threshold, the threshold can be set to about 0.1, which can ensure that the gray value of the pixel is basically unchanged before and after the modification.

Since the channel value is an integer, and we will not greatly modify the channel value when modifying, the modification range k here can take a very limited value. In order to ensure that the modification range is inversely proportional to the gray value, in the step S300 , there are multiple gray value intervals, and the modification range of the pixels in each gray value interval is the same, as long as the relationship of "when the gray value is small, the modification range is large; when the gray value is large, the modification range is small". .

时，修改幅度

；当

时，修改幅度

；当

时，修改幅度

；其中

，也即当k₂取4的时候，k₃只能取2或3。这里的具体数值，只是一个较为优选的方案，实际可以选择其他的数值。Here, the relationship between the modification amplitude and the gray value is explained in detail by taking an example. Specifically, there are three gray intervals: when

, the modification range

;when

, the modification range

;when

, the modification range

;in

, that is, when k ₂ takes 4, k ₃ can only take 2 or 3. The specific numerical value here is only a relatively preferred solution, and other numerical values can actually be selected.

Further, since the contribution of channel B to the grayscale value is small, in order to ensure the consistency of grayscale, in the present invention, preferably, in the step S300, when the three-channel parameter value of the pixel point is modified, the change of channel B The value is the modification amplitude k, and the change value of channel R and channel G is equal to 0 or 1 or -1 to ensure that the change of the gray value of the pixel point before and after modification is less than the set threshold. Here, channel B is selected as the main modification channel, and the value range of the modification amplitude k can be increased. After selecting channel R or G as the main modification channel, it is not conducive to maintaining grayscale consistency.

时，像素点修改后的r、g、b三通道参数值分别等于R+1、G+1、B-8或分别等于R+1、G+1、B-7；当

时，像素点修改后的r、g、b三通道参数值分别等于R、G+1、B-5；当

时，像素点修改后的r、g、b三通道参数值分别等于R+1、G、B-3或分别等于R-1、G+1、B-3。该具体实施方式，是修改效果非常好的优选方案。修改的时候，对于待嵌入图片的任一像素点，先判断水印矩阵图对应像素点的参数是0还是1，如果是1，再结合该像素点的灰度值和这里的判断步骤进行RGB三通道参数值的修改。如果是0，可以不修改，也可以反向修改，第一个修改方式R+1、G+1、B-8的反向修改即R-1、G-1、B+8，具体的修改情况这里不做详述，我们只需要有修改，体现出不同，就能进行水印的嵌入。More specifically, when

When the pixel point is modified, the three channel parameter values of r, g and b are respectively equal to R+1, G+1, B-8 or respectively equal to R+1, G+1, B-7; when

, the modified r, g, b three channel parameter values of the pixel point are equal to R, G+1, B-5 respectively; when

, the modified r, g, b three channel parameter values of the pixel point are respectively equal to R+1, G, B-3 or respectively equal to R-1, G+1, B-3. This specific embodiment is a preferred solution with very good modification effect. When modifying, for any pixel to be embedded in the picture, first determine whether the parameter of the corresponding pixel of the watermark matrix is 0 or 1, if it is 1, then combine the gray value of the pixel and the judgment steps here to perform RGB three. Modification of channel parameter values. If it is 0, you can not modify it, or you can modify it in the reverse direction. The first modification method is the reverse modification of R+1, G+1, and B-8, that is, R-1, G-1, and B+8. The specific modification The situation is not described in detail here, we only need to modify it to reflect the difference, and then we can embed the watermark.

Referring to Figure 2, in the invention patent "Watermark Generation and Decoding Method and Storage Medium, Electronic Equipment" (application number: 2021107265874) applied by our company, when decoding the watermark, a random template R needs to be used, which requires embedding The party and the extractor can communicate and transmit the random template R, which is very inconvenient and insecure in the use process. Preferably in the present invention, in the step S100, the random template R is a binarized image of a preset size; the information to be embedded includes a binary number of N-bit information, where N is an integer; Encoding with R: S101, add 1 to the first position of the N-bit binary number, and then convert the N+1-bit binary number into a two-dimensional matrix; S102, judge the two-dimensional matrix sequentially from left to right and top to bottom The element value in the matrix. If the element is the first row and the first column, the image of the random template R is used to represent the element. If the element value is the same as the previous element value, the image of the random template R is used to represent the element. , if the element value is different from the previous element value, the reverse image of the random template R is used to represent the element. By encoding in this way, decoding can be performed without using random template R, because binary information is represented by differentiation here, and encoding according to the above steps improves the convenience and security of decoding.

Referring to Figure 3, a picture watermark embedding system that can adaptively adjust the embedding strength, including a watermark pattern generation module, for encoding according to the random module R and the binarized information to be embedded to obtain a binarized watermark pattern; watermark matrix; The generation module is used to generate a watermark matrix map with the same size as the picture to be embedded according to the watermark pattern; the watermark overlay module is used for each pixel according to the gray value of the pixel to be embedded, the watermark matrix map, and the preset modification range. The three-channel parameter value of the pixel point is modified to obtain the image embedded with the watermark, and the modification magnitude is inversely proportional to the gray value of the pixel point. Generate a watermark pattern according to the random template R and the information to be embedded, and then generate a watermark matrix image according to the watermark pattern, which can easily obtain a watermark image of the same size as the image to be embedded. When superimposing, modify the pixel values of the RGB three channels to It is convenient to embed the watermark, and when modifying, let the modification range be inversely proportional to the gray value, that is, the modification range is small under the light background, and the modification range is large under the dark background, so that the adaptive modification of the modification range is realized. , which improves the invisible effect of the watermark and is not easy to be detected.

The present invention also discloses a computer-readable storage medium and an electronic device, wherein a computer-readable storage medium stores a computer program thereon, and when the computer program is executed by a processor, implements any of the foregoing An image watermark embedding method that can adaptively adjust the embedding strength. An electronic device includes a memory, a processor, and a computer program stored on the memory. When the processor executes the computer program, any one of the foregoing image watermark embedding methods capable of adaptively adjusting the embedding strength is implemented.

Claims (10)

1. a picture watermark embedding method capable of adaptively adjusting embedding strength, is characterized in that: comprise the steps: S100, encoding according to the random module R and the binarized information to be embedded to obtain a binarized watermark pattern; S200, tiling the watermark pattern horizontally and vertically to the width and height of the picture to be embedded, to obtain a watermark matrix diagram; S300, in the RGB color space, according to the content of the watermark matrix image, modify the three-channel parameter value of each pixel point of the image to be embedded, and the modification magnitude is inversely proportional to the gray value of the pixel point. 2. The image watermark embedding method capable of adaptively adjusting embedding strength as claimed in claim 1, wherein: in the step S300, the modification amplitude

, where R, G, B, and r, g, and b represent the three-channel parameter values of the pixel before and after the modification; the gray value of the pixel

, the change of gray value of pixels before and after modification is less than the set threshold. 3. The image watermark embedding method of claim 2, wherein in the step S300, a plurality of gray value intervals are provided, and the pixel points in each gray interval are modified The magnitude is the same. 4. The picture watermark embedding method that can adaptively adjust the embedding intensity as claimed in claim 2, it is characterized in that: described gray scale interval has three: when

, the modification range

; when

, the modification range

; when

, the modification range

; in

. 5. The image watermark embedding method of claim 2, wherein in the step S300, when the three-channel parameter value of the pixel is modified, the change value of the channel B is The modification amplitude k, the change value of channel R and channel G is equal to 0 or 1 or -1 to ensure that the change of the gray value of the pixel point before and after the modification is less than the set threshold. 6. The picture watermark embedding method of adaptively adjusting embedding strength as claimed in claim 4, is characterized in that: when

When the pixel point is modified, the three-channel parameter values of r, g, and b are respectively equal to R+1, G+1, B-8 or respectively equal to R+1, G+1, B-7; when

When the pixel point is modified, the three channel parameter values of r, g and b are respectively equal to R, G+1, B-5; when

, the modified r, g, b three channel parameter values of the pixel point are respectively equal to R+1, G, B-3 or respectively equal to R-1, G+1, B-3. 7. The image watermark embedding method of claim 1, wherein in the step S100, the random template R is a binarized image of a preset size; the information to be embedded comprises A binary number of N-bit information, where N is an integer; the random template R is encoded as follows: S101, adding 1 to the first position of the N-bit binary number, and then converting the N+1-bit binary number into a two-dimensional matrix; S102. Determine the element values in the two-dimensional matrix in the order from left to right and top to bottom. If the element is the first row and the first column, the image of the random template R is used to represent the element. If the value is the same as the previous element value, the image of the random template R is used to represent the element. If the element value is different from the previous element value, the reverse image of the random template R is used to represent the element. 8. A picture watermark embedding system capable of adaptively adjusting embedding strength, characterized in that: comprising: The watermark pattern generation module is used for encoding according to the random module R and the binarized information to be embedded to obtain a binarized watermark pattern; The watermark matrix generation module is used to generate a watermark matrix diagram with the same size as the image to be embedded according to the watermark pattern; The watermark superposition module is used to modify the three-channel parameter value of each pixel point according to the gray value of the pixel points in the image to be embedded, the watermark matrix map, and the preset modification range to obtain the image embedded with the watermark, where the modification range is the same as the pixel value. The gray value of the point is inversely proportional. 9. A computer-readable storage medium, characterized in that: a computer program is stored thereon, and when the computer program is executed by a processor, the adaptively adjustable embedding according to any one of claims 1-7 is realized. Intensity image watermark embedding method. 10. An electronic device, characterized in that it comprises a memory, a processor and a computer program stored on the memory, and when the processor executes the computer program, the computer program according to any one of claims 1-7 is realized. An image watermark embedding method that can adaptively adjust the embedding strength.

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