CN109102454A - A kind of colored QR code digital blind watermark method merging Fast Fourier Transform (FFT) - Google Patents

Abstract

The advantage that the present invention combination Spatial Domain Digital Watermarking algorithm speed of service is fast and Frequency Field Digital Watermarking Algorithm robustness is high discloses a kind of colored QR code digital blind watermark method for merging Fast Fourier Transform (FFT).The present invention is according to the monopolizing characteristic of Fast Fourier Transform (FFT) DC coefficient, the DC coefficient of the Fast Fourier Transform (FFT) of image block is obtained in airspace, and embedding algorithm and Blind extracting are completed in airspace using the DC coefficient, it can be completed without carrying out real Fast Fourier Transform (FFT).Colored QR code digital watermarking can be embedded into colored host image by the invention; not only there is preferable watermark concealment and stronger robustness; and there is preferable real-time; solve the problems, such as that the large capacity Watermarking for Color Images speed of service is slow, suitable for quick, the efficient occasion for carrying out digital media rights protection.

Description

A kind of colored QR code digital blind watermark method merging Fast Fourier Transform (FFT)

Technical field

The invention belongs to field of information security technology, are related to the quick copyright of the strong robust Color Image Watermark image of high capacity Protection.

Background technique

With the fast development of multimedia technology, more and more color digital images emerge in large numbers, propagate on network and at For one of the main media of present information, the illegal acts such as the following pirate, infringement are commonplace, Copyright Protection Also increasingly by the extensive concern of domestic and foreign scholars.For this purpose, on the one hand require the mark of copyright protection be intended to it is both artistic and practical, The Watermarking for Color Images of high capacity, and it is no longer limited to the lesser pseudo-random sequence of capacity, bianry image or gray level image； On the other hand, with widely available, the existing watermarking algorithm of mobile terminal device, especially with artificial intelligence, depth The digital watermarking algorithm of the technologies such as habit is needed because its longer runing time is difficult to meet fast and efficiently application demand into one Step improves its speed of service.

According to the difference of host image working field, digital watermarking algorithm mainly has airspace digital watermarking algorithm and frequency domain digital Watermarking algorithm；The former has the advantages that algorithm is simple, operation is fast, has the shortcomings that robustness is weak, though and the latter has robust The strong advantage of property, but its corresponding transform domain direct transform and inverse transformation cause watermarking algorithm runing time longer, affect algorithm Real-time, practicability and replicability.Therefore, the advantages of how sufficiently combining the two design robustness is strong, real-time is good Digital watermarking algorithm becomes one of urgent problem to be solved.

Summary of the invention

It is special the object of the present invention is to provide a kind of colored QR code digital blind watermark method for merging Fast Fourier Transform (FFT) What sign was to realize by specific watermark telescopiny and extraction process, watermark telescopiny is described as follows:

Step 1: the pretreatment operation of image: being by a width sizeM×M24 colored host imagesHIt is divided into red, green, blue three A Color ChannelH _i , each channel, which is divided into size, ism×mNon-overlap block of pixels；It is by a width sizeN×N24 coloured silks Color QR code watermark imageWIt is also classified into three Color Channels of red, green, blueW _i , and successively by each Color ChannelW _i It carries out based on keyKa _i Arnold scramble transformation, and by channelW _i Each decimal system pixel value to be converted to length be 8 binary numerals, It willW _i In binary numeral be successively spliced into the character string sequence of watermarkSW _i ,SW _i Total lengthlenwForN×N× 8, whereini=1,2,3, respectively indicate three Color Channels of red, green, blue；

Step 2: positioning insertion block of pixels and determining watermark bit to be embedded: utilizing positional matrix selection insertion block of pixelsBlock, The positional matrix is by based on keyKb _i Hash pseudorandom scrambling algorithm generate；Meanwhile in sequence from corresponding channel Binary-coded character string sequenceSW _i It is middle to read thejA watermark bit to be embeddedw _j , wherein 1≤j≤lenw,i=1,2,3, it respectively indicates Three Color Channels of red, green, blue；

Step 3: directly acquiring the DC component in Fast Fourier Transform (FFT) result in airspace by formula (1)tmax, and be somebody's turn to do DC component does not need to carry out real Fast Fourier Transform (FFT) to acquire；

(1)

Wherein,p、 qIt is pixel in insertion block of pixelsblockThe position of middle row, column,It is block of pixelsblockIn ThepRow, theqThe pixel value of column position,,m It is insertion block of pixelsblockWidth (or height)；

Step 4: calculating DC component using formula (2), (3)tmaxLower border valueC _low And upper boundary valuesC _high :

(2)

(3)

Wherein,w _j It isjA watermark bit to be embedded, 1≤j≤lenw, floor () is downward bracket function,TFor quantization step It is long；

Step 5: according to formula (4) from up-and-down boundary valueC _high WithC _low Middle selection optimal boundary valuecc:

(4)

Wherein, abs () is ABS function；

Step 6: calculating the block of pixels containing watermark: utilizing formula (5) by the variable quantity of DC componentchangeIt is uniformly distributed in It is embedded in block of pixelsblockIn interior all pixels, the block of pixels containing watermark can be obtainedblocknew, and be renewed back to opposite The Color Channel answered；

(5)

Wherein,change=cc-tmax,m It is insertion block of pixelsblockWidth (or height)；

Step 7: circulation executes three face of the second step to the 6th step, after all watermark bits are respectively embedded in piecemeal Until chrominance channel, finally, can be obtained three Color Channel recombinations of red, green, blue containing watermark containing watermarking imagesH*；

Its watermark extraction process is described as follows:

Step 1: pretreatment contains watermarking imagesH*: watermarking images will be containedH*It is divided into three Color Channels of red, green, blue, Ini=1,2,3, three Color Channels of red, green, blue are respectively indicated, each channel, which is divided into size, ism×mNon-overlap pixel Block；

Step 2: positioning block of pixels: in Color ChannelIn, using based on keyHash pseudorandom scrambling algorithm it is raw At positional matrix determine block of pixelsblock*；

Step 3: directly acquiring the DC component in Fast Fourier Transform (FFT) result in airspace by formula (6)tmax*, and be somebody's turn to do DC component does not need to carry out real Fast Fourier Transform (FFT) to acquire；

(6)

Wherein,p、q It is pixel in block of pixelsblock*The position of middle row, column,It is block of pixelsblock*In ThepRow, theqThe pixel value of column position,,m It is block of pixelsblock*Width (or height)；

Step 4: extracting the using formula (7)jA watermark bitw _j , wherein 1≤j≤lenw；

(7)

Wherein, mod () is MOD function, and round () is the function that rounds up；

Step 5: circulation executes second step to the 4th step, the binary-coded character string sequence in each channel is obtained respectivelySW _i *, then It willSW _i *It is one group with every 8 strings of binary characters and is converted to metric pixel value, whereini=1,2,3, respectively indicate it is red, Green, blue three Color Channels；

Step 6: being carried out the decimal system pixel value in each channel respectively based on keyKa _i Inverse Arnold conversion, at this time just obtain The watermark in each channel, whereini=1,2,3, respectively indicate three Color Channels of red, green, blue；

Step 7: recombinating the watermark in each channelObtain 24 colored QR code watermark images。

This method utilizes the principle for acquiring the DC coefficient of Fast Fourier Transform (FFT) in airspace and the coefficient modifying amount in sky The regularity of distribution of domain pixel, be done directly in airspace need the digital watermark embedding that is carried out in Fast Fourier Transform (FFT) with Blind extracting；This method had not only had preferable watermark robustness, but also algorithm real-time with higher, simple and fast.

Detailed description of the invention

Fig. 1 (a), Fig. 1 (b) are two width original color host images.

Fig. 2 is a width original color QR code watermark image.

Fig. 3 (a), Fig. 3 (b) are obtained by watermark shown in Fig. 2 to be sequentially embedded to host image Fig. 1 (a), Fig. 1 (b) afterwards Contain watermarking images, structural similarity SSIM value is successively 0.9042,0.8815, and Y-PSNR PSNR value is successively 35.9099dB、35.8736dB。

Fig. 4 (a), Fig. 4 (b) are the watermark successively extracted from Fig. 3 (a), Fig. 3 (b), normalized-cross-correlation function NC value It is 1.0000,1.0000 respectively.

Fig. 5 (a), Fig. 5 (b), Fig. 5 (c), Fig. 5 (d), Fig. 5 (e) are will to contain watermarking images shown in Fig. 3 (a) successively to carry out It is mentioned after the attacks such as JPEG2000 compression (7:1), salt-pepper noise (3%), JPEG compression (60), shearing (12.5%), scaling (75%) The watermark taken, normalized-cross-correlation function NC value are 0.9516,0.9728,0.9588,0.9271,0.9843 respectively.

Fig. 6 (a), Fig. 6 (b), Fig. 6 (c), Fig. 6 (d), Fig. 6 (e) are successively to carry out shown in Fig. 3 (b) containing watermarking images It is mentioned after the attacks such as JPEG2000 compression (7:1), salt-pepper noise (3%), JPEG compression (60), shearing (12.5%), scaling (75%) The watermark taken, normalized-cross-correlation function NC value are 0.9921,0.9782,0.9481,0.9271,0.9966 respectively.

Specific embodiment

It is special the object of the present invention is to provide a kind of colored QR code digital blind watermark method for merging Fast Fourier Transform (FFT) What sign was to realize by specific watermark telescopiny and extraction process, watermark telescopiny is described as follows:

Step 1: the pretreatment operation of image: by 24 colored host images that a width size is 512 × 512HBe divided into it is red, green, Blue three Color ChannelsH _i , by each channel be divided into size be 2 × 2 non-overlap block of pixels (sum of host image piecemeal are as follows: (512 × 512)/(2 × 2)=65536)；24 colour QR code watermark images for being 64 × 64 by a width sizeWBe also classified into it is red, Green, blue three Color ChannelsW _i , and successively by each Color ChannelW _i It carries out based on keyKa _i Arnold scramble transformation, and will ChannelW _i Each decimal system pixel value be converted to length be 8 binary numeral (such as: metric pixel value 225 Being converted to 8 bit binary value is 11100001), to incite somebody to actionW _i In binary numeral be successively spliced into the character string sequence of watermarkSW _i ,SW _i Total lengthlenwIt is 64 × 64 × 8=32768 < 65536, whereini=1,2,3, respectively indicate red, green, blue three Color Channel；

Step 2: positioning insertion block of pixels and determining watermark bit to be embedded: utilizing positional matrix selection insertion block of pixelsBlock, The positional matrix is by based on keyKb _i Hash pseudorandom scrambling algorithm generate；Meanwhile in sequence from corresponding channelSW _i Binary-coded character string sequence in readjA watermark bit to be embeddedw _j , wherein 1≤j≤ 32768,i=1,2,3, difference table Show three Color Channels of red, green, blue；Herein, if the insertion block of pixels of selectionblockFor；

Step 3: directly acquiring the DC component in Fast Fourier Transform (FFT) result in airspace by formula (1)tmax=843, And the DC component does not need to carry out real Fast Fourier Transform (FFT) to acquire；

(1)

Wherein,p、 qIt is pixel in insertion block of pixelsblockThe position of middle row, column,It is block of pixelsblockIn ThepRow, theqThe pixel value of column position,, it is embedded in block of pixelsblockWidth (or height) be 2；

Step 4: calculating DC component using formula (2), (3)tmaxLower border valueC _low And upper boundary valuesC _high :

(2)

(3)

Wherein,w _j It isjA watermark bit to be embedded, 1≤j≤ 32768, floor () are downward bracket function,TFor quantization step It is long；At this point, set watermark information position to be embedded as ' 1 ',T=80, then according to formula (2), (3), obtainC _low =784,C _high =864；

Step 5: according to formula (4) from up-and-down boundary valueC _high WithC _low Middle selection optimal boundary valuecc:

(4)

Wherein, abs () is ABS function；At this point, obtaining optimal boundary value according to formula (4)cc= C _high =864；

Step 6: calculating the block of pixels containing watermark: utilizing formula (5) by the variable quantity of DC componentchangeIt is uniformly distributed in It is embedded in block of pixelsblockIn interior all pixels, the block of pixels containing watermark can be obtainedblocknew, and be renewed back to opposite The Color Channel answered；

(5)

Wherein,change=cc-tmax=864-843=21, at this point,blocknew=；

Step 7: circulation executes three face of the second step to the 6th step, after all watermark bits are respectively embedded in piecemeal Until chrominance channel, finally, can be obtained three Color Channel recombinations of red, green, blue containing watermark containing watermarking imagesH*；

Its watermark extraction process is described as follows:

Step 1: pretreatment contains watermarking imagesH*: watermarking images will be containedH*It is divided into three Color Channels of red, green, blue, Ini=1,2,3, three Color Channels of red, green, blue are respectively indicated, each channel is divided into the non-overlap pixel that size is 2 × 2 Block；

Step 2: positioning block of pixels: in Color ChannelIn, using based on keyHash pseudorandom scrambling algorithm it is raw At positional matrix determine block of pixelsblock*；

Step 3: directly acquiring the DC component in Fast Fourier Transform (FFT) result in airspace by formula (6)tmax*, and The DC component does not need to carry out real Fast Fourier Transform (FFT) to acquire；

(6)

Wherein,p、q It is pixel in block of pixelsblock*The position of middle row, column,It is block of pixelsblock*In ThepRow, theqThe pixel value of column position,；At this point, setting the image block of selectionblocknew* it is, then obtained using formula (6)tmax*=864;

Step 4: extracting the using formula (7)jA watermark bitw _j , wherein 1≤j≤32768；

(7)

Wherein, mod () is MOD function, and round () is the function that rounds up；At this point,T=80,tmax*=864, utilize formula (7) extracting contained watermark information position is ' 1 '；

Step 5: circulation executes second step to the 4th step, the binary-coded character string sequence in each channel is obtained respectivelySW _i *, then It willSW _i *It is one group with every 8 strings of binary characters and is converted to metric pixel value, whereini=1,2,3, respectively indicate it is red, Green, blue three Color Channels；

Step 6: being carried out the decimal system pixel value in each channel respectively based on keyKa _i Inverse Arnold conversion, at this time just obtain The watermark in each channel, whereini=1,2,3, respectively indicate three Color Channels of red, green, blue；

Step 7: recombinating the watermark in each channelObtain 24 colored QR code watermark images。

This method both has the advantages that Frequency Field Digital Watermarking Algorithm, it may have the advantages of Spatial Domain Digital Watermarking algorithm, robust Property it is strong, real-time is high, and watermark invisibility is good；Algorithm is simple and fast, suitable for high capacity color image as digital watermarking Efficient copyright protection.

Validation verification of the present invention

In order to prove effectiveness of the invention, selecting the two width sizes as shown in Fig. 1 (a), Fig. 1 (b) is 24 of 512 × 512 Standard picture is tested as host image, and with 24 colour QR code watermark images that size as shown in Figure 2 is 64 × 64 Card.

Fig. 3 (a), Fig. 3 (b) are that watermark shown in Fig. 2 (a) is sequentially embedded to host image Fig. 1 (a), Fig. 1 (b) institute afterwards What is obtained contains watermarking images, and structural similarity SSIM value is successively 0.9042,0.8815, and Y-PSNR PSNR value is successively It is 35.9099dB, 35.8736dB；Fig. 4 (a), Fig. 4 (b) are the watermark successively extracted from Fig. 3 (a), Fig. 3 (b), normalization Cross-correlation coefficient NC value is 1.0000,1.0000 respectively；Fig. 5 (a), Fig. 5 (b), Fig. 5 (c), Fig. 5 (d), Fig. 5 (e) are by Fig. 3 (a) JPEG2000 compression (7:1), salt-pepper noise (3%), JPEG compression (60), shearing are successively carried out containing watermarking images shown in (12.5%), extracted watermark after the attack such as (75%) is scaled, normalized-cross-correlation function NC value is 0.9516 respectively, 0.9728、0.9588、0.9271、0.9843。

Fig. 6 (a), Fig. 6 (b), Fig. 6 (c), Fig. 6 (d), Fig. 6 (e) are successively to carry out shown in Fig. 3 (b) containing watermarking images It is mentioned after the attacks such as JPEG2000 compression (7:1), salt-pepper noise (3%), JPEG compression (60), shearing (12.5%), scaling (75%) The watermark taken, normalized-cross-correlation function NC value are 0.9921,0.9782,0.9481,0.9271,0.9966 respectively.

The algorithm is in platform 2.8GHZ CPU, 4.00GB RAM, Win 8.1, MATLAB 9.2.0.538062 (R2017a) nearly ten thousand operations were carried out on, the average insertion time of digital watermarking is 0.306250 second, average extraction time It is 0.309944 second, the total time is 0.616194 second.

In conclusion embedded colored QR code digital watermarking has preferable invisibility, watermarking algorithm is met Invisibility requirement；Meanwhile extracted colour QR code watermark image is with higher recognizable from various under fire images Property and higher NC value, illustrate this method have stronger robustness；In addition, the average operation total time of the algorithm less than 1 second, Meet the needs of the quick copyright protection of multimedia big data.

Claims (1)

1. a kind of colored QR code digital blind watermark method for merging Fast Fourier Transform (FFT), it is characterised in that pass through specific watermark Come what is realized, watermark telescopiny is described as follows for telescopiny and extraction process:

Step 1: the pretreatment operation of image: being by a width sizeM×M24 colored host imagesHIt is divided into red, green, blue three A Color ChannelH _i , each channel, which is divided into size, ism×mNon-overlap block of pixels；It is by a width sizeN×N24 coloured silks Color QR code watermark imageWIt is also classified into three Color Channels of red, green, blueW _i , and successively by each Color ChannelW _i It carries out based on keyKa _i Arnold scramble transformation, and by channelW _i Each decimal system pixel value to be converted to length be 8 binary numerals, It willW _i In binary numeral be successively spliced into the character string sequence of watermarkSW _i ,SW _i Total lengthlenwForN×N× 8, whereini=1,2,3, respectively indicate three Color Channels of red, green, blue；

Step 2: positioning insertion block of pixels and determining watermark bit to be embedded: utilizing positional matrix selection insertion block of pixelsBlock, The positional matrix is by based on keyKb _i Hash pseudorandom scrambling algorithm generate；Meanwhile in sequence from corresponding channel Binary-coded character string sequenceSW _i It is middle to read thejA watermark bit to be embeddedw _j , wherein 1≤j≤lenw,i=1,2,3, it respectively indicates Three Color Channels of red, green, blue；

Step 3: directly acquiring the DC component in Fast Fourier Transform (FFT) result in airspace by formula (1)tmax, and be somebody's turn to do DC component does not need to carry out real Fast Fourier Transform (FFT) to acquire；

(1)

Wherein,p、 qIt is pixel in insertion block of pixelsblockThe position of middle row, column,It is block of pixelsblockIn ThepRow, theqThe pixel value of column position,,m It is insertion block of pixelsblockWidth (or height)；

Step 4: calculating DC component using formula (2), (3)tmaxLower border valueC _low And upper boundary valuesC _high :

(2)

(3)

Wherein,w _j It isjA watermark bit to be embedded, 1≤j≤lenw, floor () is downward bracket function,TFor quantization step；

Step 5: according to formula (4) from up-and-down boundary valueC _high WithC _low Middle selection optimal boundary valuecc:

(4)

Wherein, abs () is ABS function；

Step 6: calculating the block of pixels containing watermark: utilizing formula (5) by the variable quantity of DC componentchangeIt is uniformly distributed in It is embedded in block of pixelsblockIn interior all pixels, the block of pixels containing watermark can be obtainedblocknew, and be renewed back to opposite The Color Channel answered；

(5)

Wherein,change=cc-tmax,m It is insertion block of pixelsblockWidth (or height)；

Step 7: circulation executes three face of the second step to the 6th step, after all watermark bits are respectively embedded in piecemeal Until chrominance channel, finally, can be obtained three Color Channel recombinations of red, green, blue containing watermark containing watermarking imagesH*；

Its watermark extraction process is described as follows:

Step 1: pretreatment contains watermarking imagesH*: watermarking images will be containedH*It is divided into three Color Channels of red, green, blue, whereini=1,2,3, three Color Channels of red, green, blue are respectively indicated, each channel, which is divided into size, ism×mNon-overlap pixel Block；

Step 2: positioning block of pixels: in Color ChannelIn, using based on keyHash pseudorandom scrambling algorithm it is raw At positional matrix determine block of pixelsblock*；

Step 3: directly acquiring the DC component in Fast Fourier Transform (FFT) result in airspace by formula (6)tmax*, and be somebody's turn to do DC component does not need to carry out real Fast Fourier Transform (FFT) to acquire；

(6)

Wherein,p、q It is pixel in block of pixelsblock*The position of middle row, column,It is block of pixelsblock*InpRow, theqThe pixel value of column position,,m It is block of pixelsblock*Width (or height)；

Step 4: extracting the using formula (7)jA watermark bitw _j , wherein 1≤j≤lenw；

(7)

Wherein, mod () is MOD function, and round () is the function that rounds up；

Step 5: circulation executes second step to the 4th step, the binary-coded character string sequence in each channel is obtained respectivelySW _i *, then It willSW _i *It is one group with every 8 strings of binary characters and is converted to metric pixel value, whereini=1,2,3, respectively indicate it is red, Green, blue three Color Channels；

Step 6: being carried out the decimal system pixel value in each channel respectively based on keyKa _i Inverse Arnold conversion, at this time just obtain The watermark in each channel, whereini=1,2,3, respectively indicate three Color Channels of red, green, blue；

Step 7: recombinating the watermark in each channelObtain 24 colored QR code watermark images。