CN100521765C - Video frequency digital water mark enciphering marking and detecting method - Google Patents

Abstract

A method for detecting and random-labeling object sample includes labeling Ni numbers of samples in sample space containing N numbers of samples inrepeatedly and randomly with nl being less than N and labeling ratio being k=nl/N, calculating out critical random sampling quantity N2 by utilizing specific formula as per labeling ratio K, selecting N2 numbers of samples from sample space inrepeatedly and randomly with N2being no less than critical random sampling quantity N2 for sure to find out a labeled sample .

Description

Mark and detection method that video digital watermark is encrypted

(1) technical field under

The present invention relates to a kind of target sample random labelling and detection method, and the application on video digital watermark is encrypted.

(2) background technology

In the research and application in fields such as many physics, chemistry, geology; usually can run into such class difficult problem: detect target sample how accurately, fast and efficiently, the video digital watermark encryption technology application that is used for copyright protection in the electronic information technology research field is a good example.

Along with the develop rapidly and the application popularization of network technology and digital multimedia technology, digital watermark technology is subject to people's attention just day by day as a kind of effective means of digital copyright protecting.The embedding of watermark is similar to the mark of target sample, extracts the detection that then is similar to target sample, and the embedding of watermark and leaching process are appreciated that and reduce the mark and the detection of target sample, and especially the selection of watermark embedding frame and search procedure are typical more.Although the development of more than ten years has been experienced in the research of digital watermark technology, many theories and algorithm have appearred, still rest on conceptual phase mostly, the quantity of real practical application is seldom.From the content of concrete research, the overwhelming majority still is confined to image digital watermark, and relative less to the research of multimedia (comprising video and audio frequency) digital watermarking.This is owing to the demand point of the multimedia digital watermark that derives from practical application is also very not clear and definite on the one hand, does not form better technology application model; Be because multimedia file quantity is many, the file data amount is big on the other hand, and be applied to network environment more, also there are many basic problems that solve that are difficult in the technical elements of its digital watermarking, as modal in the video digital watermark, also be that problem is attacked in the most scabrous frame montage.

The general requirement of digital watermarking has hiding property and two critical natures of robustness, and in video digital watermark, because many, the data volume of video file is big, real-time requires height, except that the fundamental property that possesses above two digital watermarkings, also should satisfy following some:

1. video digital watermark (in particular for the video digital watermark of copyright supervision and control) should be a kind of blind watermark, should not need the help of original video files in watermark detection process again;

2. video digital watermark should be able to be resisted based on the modal frame montage attack of video file, comprises frame replacement, frame reorganization, frame interpolation, frame deletion etc.; Otherwise, only needing simple several frame editing operations, watermark has not just existed.Therefore, attack, just lost its actual application value if a kind of good again video digital watermark algorithm can not be resisted the frame montage.

3. the detection speed of video digital watermark should be enough fast, can satisfy the online detection requirements under the network environment.Video digital watermark more should be brought into play its function aspect copyright supervision and control except the copyright authentication function that should have image digital watermark (off-line is finished).This just requires the detection algorithm complexity of watermark enough low, and detection time is short, and the user can be restrained oneself.

At present, also find to satisfy fully the embedding grammar and the detection method of the video digital watermark of above three conditions.

(3) summary of the invention

One object of the present invention, be to provide a kind of accurately, target sample random labelling, detection method fast and efficiently.

Another object of the present invention, be to provide a kind of video digital watermark encrypt in to the mark and the detection method of encrypted frame, promptly embed the video digital watermark method that extracts with random frame based on random frame.

A。About target sample random labelling and detection method, specifically be discussed below:

1 one kinds of target sample random labellings, detection method may further comprise the steps:

1. in a sample space that contains N sample, not repeatedly, mark n wherein randomly ₁Individual sample, wherein n ₁＜N, the mark ratio $k=\frac{n_1}{N};$

2. calculate critical stochastical sampling quantity n according to mark ratio k according to following formula ₂':

Wherein, the ceil in the above-mentioned formula represents to round to big number;

3. picked at random n repeatedly not from sample space ₂Individual sample, wherein n ₂More than or equal to critical with

Machine number of samples n ₂', then will inevitably find one and be labeled sample.

In the target sample random labelling and detection method of the invention described above, the general value of described mark ratio k is 10～50%; Best value 20～30%.

2 theory analysises

In a sample space that contains N sample, mark n wherein randomly ₁Individual sample (not repeating label) is equivalent to choose n randomly from N sample ₁Individual sample belongs to the category of Probability Theory and Math Statistics ^[4], total

Plant different choice.Similarly, randomly draw n wherein the second time ₂Individual sample (not repeating to extract) has

Plant different choice.So, the n that randomly draws the second time ₂Not containing the number of combinations that is labeled sample in the individual sample is

Duplicate sample in order to make in twice stochastical sampling, i.e. the n that randomly draws for the second time ₂At least contain a probability that is labeled sample in the individual sample $P_{n_2}(N,n_1)\≥99.995\%$ Set up, then need to satisfy:

$P_{n_2}(N,n_1)=\frac{C_N^{n_2}-C_{N-n_1}^{n_2}}{C_N^{n_2}}\×100\%\≥99.995\%---\left(1\right)$

Wherein, $C_n^m=\frac{n\×(n-1)\×(n-2)\·\·\·(n-m+1)}{m\×(m-1)\·\·\·\×2\×1}.$

Formula (1) has provided in twice stochastical sampling and the accurate conditional relationship that sample repeats occurred.Because this formula is too complicated, there be the computing of multistage layer, its operand and computational complexity are all bigger, are difficult to directly be used to determine n ₂Span.More wish in actual applications to find a kind of intuitively, method is determined n fast ₂And scope.

Formula (1) has provided n when occurring the sample repetition in twice stochastical sampling in fact ₂Need the satisfied inequality that concerns, wherein have a critical stochastical sampling quantity n ₂'.n ₂' satisfy relational expression:

$P_{n_2}(N,n_1){|}_{n_2=n_2\′}\≥99.995\%\≥P_{n_2}(N,n_1){|}_{n_2=n_2\′-1}---\left(2\right)$

Thus, can change an angle, finding the solution of formula (1) is converted to seek critical stochastical sampling quantity n ₂', the accurate conditional relationship of same up-to-date style (1) is converted to n ₂〉=n ₂'.

3 critical stochastical sampling quantity n ₂' numerical solution

Utilize Matlab 6.5 experiment porchs to carry out critical stochastical sampling quantity n ₂' numerical solution, concrete solution procedure is as follows:

(1) contains N=10 at one ⁴In the sample space of individual sample, mark 10% sample wherein randomly

This (not repeating label), i.e. n ₁=N * 10%.

(2) with n ₂Be spaced apart 1 since 1 and progressively increase, calculate corresponding probability respectively $P_{n_2}(N,n_1)=\frac{C_N^{n_2}-C_{N-n_1}^{n_2}}{C_N^{n_2}}\×100\%,$ Find first n that satisfies formula (1) ₂Value, and be designated as n ₂'.

(3) random labelling ratio k is increased to 100% successively since 10% with 10% interval, i.e. n ₁=k * 10% * N, k=1,2 ..., 10.Repeating step (1) (2) writes down corresponding n ₂'.

(4) sample space quantity N being increased successively is 10 ⁶, 10 ⁸, repeating step (1)～(3).

Result of calculation is as shown in table 1.

Table 1 is fixing $P_{n_2}(N,n_1)=99.995\%,$ N=10 ⁴, 10 ⁶, 10 ⁸The time critical stochastical sampling quantity n ₂'

Can obviously find out from table 1: when occurring the sample repetition twice stochastical sampling, critical stochastical sampling quantity n ₂' along with mark ratio k (perhaps mark quantity n ₁) increase and reduce, the expressive notation ratio is big more, and then to detect the feasibility of target sample big; Simultaneously, with random sample mark quantity n ₁Compare n ₂' much smaller (be n ₂The n of '＜＜ ₁), expression can be used fully much smaller than marker samples quantity n ₁Stochastical sampling realize the detection of sample; More importantly, under the certain situation of mark ratio, n ₂' value be identical, i.e. n ₂' only relevant with the mark ratio.

Provide n below by curve fit ₂' approximate expression, and then make above-mentioned conclusion more clear.

4 n ₂' numerical analysis and curve fit thereof

In order to obtain n ₂' approximate expression, use the way identical with last joint, when finding the solution fix N, work as n ₁N in the change procedure progressively ₂' value, concrete solution procedure is as follows:

(1) sets N=10 ⁶, $P_{n_2}(N,n_1)=99.995\%,$ n ₁=1 (is that the mark ratio is 1/10 ⁶).

(2) fixing n ₁Value is with n ₂Be spaced apart 1 since 1 and progressively increase, calculate corresponding probability respectively

$P_{n_2}(N,n_1)=\frac{C_N^{n_2}-C_{N-n_1}^{n_2}}{C_N^{n_2}}\×100\%,$ Find first n that satisfies formula (1) ₂Value, and be designated as n ₂'.

(3) with n ₁Be spaced apart 1 and progressively increase up to N, repeating step (1) (2) writes down corresponding n ₂'.

When (4) drawing fix N, n ₂' with n ₁Relation curve n ₂'～n ₁, as shown in Figure 1.

(5) change N=10 ⁴, repeat (1)～(4).Curve n ₂'～n ₁As shown in Figure 2.

By Fig. 1 and Fig. 2 as can be seen, as N fixedly the time, n ₂' with n ₁Roughly become reciprocal relation, and have certain relation with N.Therefore, suppose n ₂' have a following form:

Wherein, a is a undetermined coefficient, f (N), and g (N), h (N) is a function undetermined.

On the basis of above-mentioned experimental data, Fig. 1 is carried out repeatedly piecewise fitting, obtain n ₂' with N, n ₁Variation relation, and consider n ₂' value is necessary for integer, then fitting function

(N, n ₁) as follows:

Like this, just can be according to any given N, n ₁Value calculates the n that satisfies condition easily by formula (3) ₂' value.

The mark ratio is designated as $k=\frac{n_1}{N},$ Formula (3) is become:

By formula (4) as can be seen, n ₂' only relevant with mark ratio k, be the approximate segmentation reciprocal function of k.This has further proved the result of calculation in 3 joints.Fig. 3 has shown n ₂'～k graph of a relation.

So far can obtain as drawing a conclusion: in a sample space that contains N sample, mark n wherein randomly ₁Individual sample (not repeating label).Stochastical sampling second time n wherein ₂Individual sample (not repeating to extract), n ₂As long as more than or equal to its critical stochastical sampling quantity n ₂', just can reach that sample repeats is the purpose that target sample effectively detects.Critical stochastical sampling quantity n ₂' only to account for the ratio of total sample relevant with being labeled sample at random, promptly

Target sample random labelling of the present invention and detection method have accuracy height, detection time is short, reliability is high advantage.

B. about the present invention in the video digital watermark encrypted applications, specifically be discussed below:

1 one kinds of mark and detection methods that video digital watermark is encrypted may further comprise the steps:

1. determine the totalframes N of video file according to original code check of video file, utilize random number generator produce at random not between the 1～N that repeats mutually n ₁Individual random number, and from video file, choose wherein n successively randomly according to this random number sequence ₁Frame embeds frame as watermark, wherein n ₁＜N, the mark ratio $k=\frac{n_1}{N};$

2. embed the n of algorithm by image watermark to choosing ₁Two field picture is watermarked respectively, and with watermarked n ₁Two field picture and do not have watermarked N-n ₁Two field picture reconfigures becomes the video file that has watermark information;

3. calculate critical detection frame number n according to mark ratio k ₂',

Wherein, the ceil in the above-mentioned formula represents to round to big number;

4. determine the totalframes N of video file according to original code check of video file, utilize random number generator produce at random not between the 1～N that repeats mutually n ₂Individual random number, and from video file, choose wherein n successively randomly according to this random number sequence ₂Frame is as watermark detection frame, wherein n ₂〉=n ₂';

5. by the image watermark detection algorithm n to choosing respectively ₂Two field picture carries out watermark detection, will inevitably find the watermarked image of a frame.

To the mark and the detection method of encrypted frame, described mark ratio k was generally 10～50%, is preferably 20～30% during the video digital watermark of the invention described above was encrypted.

2 theory analysises

The embedding of video digital watermark and detecting operation all are based on frame of video (as I frame, B frame, P frame) basically, but they all do not have very to clearly state and should be how embed and extract watermark in a video file that contains a lot of frames, according to default idea just should be watermarked in all frame of video, but this is difficult to possible in actual applications.Reason has two: carrying out large-scale watermark embedding in a video file is a great engineering, and the user is out of patience; Simultaneously, large-scale watermark embeds and can produce than havoc video file, has a strong impact on the video playback effect.Therefore, a kind of good video digital watermark algorithm should lack embed watermark information as much as possible, very easily detects again simultaneously, promptly between the invisibility of watermark and robustness a good balance is arranged.

According to this principle, video watermark be to select a part of frame of video as embedding frame in video file when embedding, the hiding embedding that minor modifications by video being embedded the frame fixed position or the minor modifications after the functional transformation realize watermark information; At first to find watermarked frame of video during watermark extracting, and then go to detect the minor modifications of being done when embedding in the fixed position according to the watermark extracting algorithm.If can detect the existence that watermark information has just proved watermark.So, how in the frame of video of enormous amount, to find watermarked frame of video exactly, how in watermarked frame of video, to find watermarked particular location exactly, just seem very important.Watermark in the video file is embedded the synchronizing information that the selection information of frame, embedded position information that watermark embeds watermark in the frame are referred to as watermark, the former robustness is called the interframe robustness of watermark, the latter's robustness is called robustness in the frame of watermark.Synchronizing information is destroyed, just can't find watermark to embed frame, can't find watermarked particular location, also just can't normally extract watermark.

If can from video file, select wherein a part of frame of video watermarked according to a certain percentage randomly as watermark embedding frame, select the frame of video of some to carry out watermark detection then randomly, promptly utilize method to realize video digital watermark based on random frame embeds and random frame is extracted, the embedding of video digital watermark and leaching process so, or first kind robustness problem just can to reduce that twice sample in the stochastical sampling repeat be that target sample effectively detects problem.

Rationale of the present invention is: in a sample space that contains N sample, and mark n wherein randomly ₁Individual sample (not repeating label).Randomly draw for the second time n wherein ₂Individual sample (not repeating to extract), n ₂Need satisfy any condition and just can make in twice stochastical sampling and duplicate sample, or the n that randomly draws for the second time ₂At least contain a probability that is labeled sample in the individual sample and level off to 1, be set at $P_{n_2}(N,n_1)\≥99.995\%.$

n ₂As long as more than or equal to its critical stochastical sampling quantity n ₂', just can reach that sample repeats is the purpose that target sample effectively detects.Critical stochastical sampling quantity n ₂' only to account for the mark ratio of total sample relevant with being labeled sample at random, promptly

And with total sample number amount n ₁Irrelevant.Its approximate expression is:

n ₂'～k graph of a relation as shown in Figure 3.

Embedding grammar and the detection method that embeds the video digital watermark that extracts with random frame based on random frame of the present invention, be highly resistant to common in the video digital watermark, also be that the most insoluble frame montage is attacked, have high reliability and high robust, for the practical application of video digital watermark provides guarantee.

(4) description of drawings

Fig. 1 is n ₂'～n ₁Graph of a relation, wherein $P_{n_2}(N,n_1)=99.995\%,$ N＝10 ⁶

Fig. 2 is n ₂'～n ₁Graph of a relation, wherein $P_{n_2}(N,n_1)=99.995\%,$ N＝10 ⁴

Fig. 3 is n ₂'～k graph of a relation is (fixing $P_{n_2}(N,n_1)=99.995\%$ )。

(5) embodiment

Be encrypted as example with video digital watermark below, the present invention is carried out specific description, wherein mark ratio k=30%.

1. get 1 M (0.30,28) from the relational expression of formula (1) and the relation curve of accompanying drawing 3, critical stochastical sampling quantity n when this point is illustrated in random sample mark ratio k=30% ₂'=28,28 samples of promptly sampling randomly necessarily can detect target sample.In order to increase reliability, guarantee to detect effect, with n ₂' increase a little and bring up to 30, be i.e. n ₂ Equal 30.

In a video file, choose wherein 30% frame and watermarked in each frame randomly; During watermark extracting, from video file, choose 30 frames randomly, then can find a frame to contain watermark at least, and detect watermark.

2. concrete embedding grammar and detection method can be described below:

(1) random frame embeds

1. determine the frame number of video file according to original code check of video file, suppose to contain altogether the N frame.

2. utilize random number generator to produce n ₁Random number between the individual unduplicated 1～N of=N*30%.

3. according to the order of the random number sequence between the 1～N that 2. generates, from video file, choose n wherein successively randomly ₁Frame embeds frame as watermark.

4. embed the n of algorithm by image watermark to choosing ₁Two field picture is watermarked.

5. with watermarked n ₁Frame and other N-n ₁Frame is reassembled into video file, uses as the video file issue that has watermark information.

(2) random frame is extracted

1. determine the frame number of video file according to original code check of video file, suppose to contain altogether the N frame.

2. utilize the random number between 30 unduplicated 1～N of random number generator generation.

3. according to the order of the random number sequence between the 1～N that 2. generates, from video file, choose 30 two field pictures wherein successively randomly.

4. respectively 30 two field pictures of picked at random are carried out watermark detection by the image watermark detection algorithm, and the record testing result.

5. as long as in 30 two field pictures of picked at random detect, find that a frame contains watermark, just proved in this video file watermarked.

In order to improve the robustness (being robustness in the frame) that image watermark detects, can select two class robustness effects to reach the not interactive again image watermark algorithm of complementation while embedded location and repeat to embed, thereby realize complementary detection.

3. The Realization of Simulation and attack checking

It is platform that the emulation of this video watermark algorithm is based on matlab6.5, and test procedure mainly comprises:

A) read video file, produce sequence of frames of video, altogether the N frame;

B) produce n with randomizer ₁Not repeating random number between=N*30% and 30 the 1～N, first group of random number is used for determining that watermark embeds the position of frame of video, second group of random number is used for determining the position of watermark extracting frame of video;

C) it is watermarked that the utilization image watermark embeds algorithm;

D) watermark is attacked

(1) frame of video deletion: be included in forward and backward or middle any 50 frames of deletion in the watermarked video file.

(2) frame of video exchange: watermarked frame of video and the frame of video exchange sequence before or after it, the exchange frame number is no less than 20 frames.

(3) frame of video is inserted: 50 frames are inserted in the forward and backward or middle optional position that is included in watermarked video file.

E) utilization image watermark extraction algorithm extracts watermark.

Above-mentioned algorithm is carried out emulation, adopt a large amount of video files in the experiment, file relates to scene (comprising: personage, automobile, landscape, moving object, scene switching etc.) widely, video file is carried out the frame operation attack (comprising: frame deletion, frame exchange, frame insertion etc.), filename is respectively Akiyo, Foreman, Tempete, Mobile.

The Simulation results statistics is as shown in table 1 below, and wherein normal extraction is meant without frame of video and attacks directly extraction watermark information, and the watermarking algorithm that adopts in the experiment extracts similarity in single-frame images be 1.

Table 1: experiment simulation statistics

As can be seen from the above table, the embedding ratio is 30%, extracts quantity and is under 30 the situation, and this algorithm all can effectively extract watermark information to frame operation (frame deletion, frame insert and the frame exchange), has very strong robustness.

4. conclusion: above-mentioned demonstration and emulation experiment show, the embedding grammar at random and the detection method of video digital watermark, be highly resistant to common in the video digital watermark, also be that the most insoluble frame montage is attacked, have high reliability and high robust, for the practical application of video digital watermark provides reliable guarantee.

Claims (3)

1. a mark and the detection method that video digital watermark is encrypted is characterized in that, may further comprise the steps:

1. determine the totalframes N of video file according to original code check of video file, utilize random number generator to produce not the n between 1～N of repetition mutually at random ₁Individual random number, and from video file, choose wherein n successively randomly according to this random number sequence ₁Frame embeds frame as watermark, wherein n ₁＜N, the mark ratio $k=\frac{n_1}{N};$

2. embed the n of algorithm by image watermark to choosing ₁Two field picture is watermarked respectively, and with watermarked n ₁Two field picture and do not have watermarked N-n ₁Two field picture reconfigures becomes the video file that has watermark information;

3. calculate critical detection frame number n according to mark ratio k ₂',

Wherein, the ceil in the above-mentioned formula represents to round to big number;

4. utilize random number generator to produce not the n between 1～N of repetition mutually at random ₂Individual random number, and from video file, choose wherein n successively randomly according to this random number sequence ₂Frame is as watermark detection frame, wherein n ₂〉=n ₂';

5. by the image watermark detection algorithm n to choosing respectively ₂Two field picture carries out watermark detection, will inevitably find the watermarked image of a frame.

2. mark and detection method that video digital watermark according to claim 1 is encrypted is characterized in that described mark ratio is 10-50%.

3. mark and detection method that video digital watermark according to claim 2 is encrypted is characterized in that described mark ratio is 20-30%.

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