CN108307203A - Film encryption method, decryption method based on multi-projector splicing fusion - Google Patents

Abstract

The invention belongs to the field of video encryption, specifically relates to a film encryption method and decryption method based on multi-projector splicing and fusion, and aims to solve the film source encryption and decryption technology for film copyright protection. The method includes: (1) the projection screen Parameterized division, select the encryption area; (2) use encryption software to generate a password on the target machine; (3) convert the password into a binary number, select the first n digits to generate a movie encryption mask; (4) in the process of rendering and generating a movie (5) In the playback link, call the same encryption program to generate the same password as encryption, and convert it into a binary sequence to generate splicing fusion decryption configuration parameters; (6) Splicing fusion software calls decryption Configure parameters, play encrypted video source, and realize decryption playback. The invention realizes the splicing fusion film encryption technology for special screens of multiple projectors.

Description

Video encryption method and decryption method based on multi-projector splicing and fusion

technical field

The invention belongs to the field of video encryption, and in particular relates to a video encryption method and decryption method based on multi-projector splicing and fusion.

Background technique

Curved-surface multi-projector splicing and fusion special films represented by ring screens and dome screen films are a special screen film with a large viewing angle that appeared in the early 20th century. For the shooting of movies with large viewing angles and the production of animation scenes, use ultra-wide-angle fisheye lenses or combined lenses with multi-camera images. The curtain is circular or hemispherical, and the audience is surrounded by it. Because the image has a large viewing angle for the audience and is accompanied by surround sound, the audience has a sense of being there. Due to the huge screen of the ring screen and the dome screen, and the limited space for placing the projector, a single projector cannot fill the entire screen. And because the display resolution of a single projector is limited, multiple projectors are used to splicing and merging to display the output.

Due to the large viewing angle and short viewing distance of the splicing fusion film, the resolution of the entire film source is large, the production cycle is long, and the production cost is high. Therefore, the protection of film copyright is a key issue in the development of this industry. If the film source is not encrypted, but only the playback program or splicing and fusion program is encrypted, the film cannot be well protected. Therefore, the present invention provides an encryption and decryption technology that encrypts the film source and can only be correctly decrypted and played on a designated playback machine.

Aiming at the problem of copyright protection, the present invention proposes an encryption and decryption technology based on multi-projection splicing fusion technology. This technology combines the encryption link with the parameter grid division of projection splicing fusion, Crypto++ program algorithm, and film post-production technology to generate encrypted film sources; in the decryption link, the decryption process is combined with the color change link of multi-projector splicing and fusion to decrypt play. Only when the encryption and decryption password sequences are also generated on the specified player can the correct movie playback effect be obtained. The invention realizes good protection of film sources, skillfully utilizes the technical characteristics of splicing and fusion of special films, and combines the encryption and decryption technology with the multi-projector splicing and fusion technology invented by the inventor.

The video encryption technology based on splicing and fusion consists of the following specific technical parts: the encryption part establishes a parameterized grid for the target screen, selects the encrypted area according to the parameterized grid, and then runs the Crypto++ algorithm to generate a local password and convert it into a binary sequence. Establish the corresponding relationship between the binary sequence and the parameterized grid encryption interval, and generate the encrypted watermark mask image according to the encrypted binary sequence. Use the post-production software to multiply each frame of the unencrypted film source with the watermark mask image for post-processing, and use the processed result as the encrypted film source. In the decoding and playing part, also call Crytpo++ to generate a password and convert it into a binary sequence, and also establish the correspondence between each bit in the binary sequence and each grid in the encrypted area, and unify the decryption module with the color attenuation module in the splicing fusion Form a new color transformation method to realize decryption playback. Simultaneously, for the situation of playing on other machines or venues, the correct decrypted playback result cannot be obtained due to the inconsistency between the generated decryption password and the encrypted password.

Contents of the invention

In order to solve the above-mentioned problems in the prior art, that is, in order to solve the film source encryption and decryption technology of the film copyright protection problem, one aspect of the present invention proposes a film encryption method based on multi-projector splicing and fusion, including the following steps:

Step A1, parametrically meshing the projection screen, and selecting an encrypted area;

Step A2, using encryption software to generate passwords on the target machine respectively for the parameter grid of the encryption area;

Step A3, converting the password generated in step A2 into a binary number, and selecting its first n digits to generate a movie encryption mask;

Step A4, in the process of rendering and generating the projection film, superimposing the watermark mask to generate the encrypted film.

Further, the method of "parametrically meshing the projection screen and selecting an encrypted area" is as follows:

Divide the projection screen into (M+1)*(N+1) parameter grids according to the parametric equation, where the coordinates of the parameter grid points are [i, j] (i=0,1,2,3 ...M;j=0,1,2,3...N);

Select the fusion area as the encrypted area, and determine the parameter grid corresponding to the encrypted area.

Further, the method of "converting the password generated by step A2 into a binary number and selecting its first n digits to generate a film encryption mask" is as follows:

Convert the password generated by step A2 into a binary number;

Based on the preset attenuation password generation method, calculate the grid encryption mask color RGB component color attenuation password _{E i} corresponding to the number i on the mask map.

Further, the preset attenuation password generation method is

Further, the method of "overlaying watermark mask to generate encrypted movie" is:

Encrypt each frame of the film source to be kept secret through the watermark superposition program; the encryption method is the multiplication of the watermark and the original image.

Further, the encryption software is a Crypto++ password generation library.

Another aspect of the present invention proposes a film decryption method based on multi-projector splicing and fusion, comprising the following steps:

Step B1, identifying the encryption area;

Step B2, calling the encryption software used when generating the password, and generating the same password as encryption for the parameter grid of the encryption area;

Step B3, converting the password generated in step B2 into a binary number, and generating splicing fusion decryption configuration parameters;

In step B4, the splicing and fusion software invokes the decryption configuration parameters, plays the encrypted video source, and performs decryption and playback.

Further, step B2 is performed when splicing and fusion playing is performed.

Further, the method of "converting the password generated in step B2 into a binary number to generate splicing fusion decryption configuration parameters" is:

Convert the password generated by step A2 into a binary number;

Based on the preset attenuation password generation method, calculate the grid encryption mask color RGB component color attenuation password E _i corresponding to the sequence number i on the mask graph, and generate the color enhancement password E′ _i .

Further, the preset attenuation password generation method is

The color enhanced password E′ _i is

For the encryption and decryption of special films such as ring screens and ball screens, the present invention proposes a set of technology based on the encryption of the film source, combined with splicing and fusion playback and decryption, and realizes the encryption and decryption in the process of authorized playback of films. Intellectual property protection provides a reliable guarantee. The invention cleverly utilizes the special playing mode of special films, combines encryption and decryption with film source distribution and film source play, and provides a brand new solution strategy for intellectual property protection in this field.

Description of drawings

Fig. 1 is a schematic flow diagram of a film encryption method and a decryption method based on multi-projector splicing and fusion in the present invention;

Fig. 2 is a schematic diagram of the parametric division of the curtain grid;

Fig. 3 is a corresponding schematic diagram of the corresponding relationship between the sequence and the grid;

Fig. 4 is a schematic diagram of the encryption process;

Fig. 5 is a schematic diagram of the decryption process;

Fig. 6 is an effect diagram of each link of encryption and decryption.

Detailed ways

Preferred embodiments of the present invention are described below with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are only used to explain the technical principles of the present invention, and are not intended to limit the protection scope of the present invention.

The present invention performs parametric grid division on the target projection screen, and selects the encryption area; runs the Crypto++ password generation software locally on the specified player to generate the password sequence; converts the password into a binary sequence, and combines each binary bit of the binary sequence with the encryption area One-to-one correspondence of each grid of the encryption area to generate an encrypted mask watermark image corresponding to the parameterized grid of the encrypted area; Each frame of the source is multiplied to obtain the encrypted film source; in the decryption and playback link, for the case of playing on a specified player, call Crypto++ to generate the same password as the encryption link before playing and convert it into a binary sequence. The 0 and 1 information of each bit of the sequence is used as the color fusion parameter in the decryption link, and is combined with the color intensity attenuation process of the splicing and fusion software invented by the inventor. Generate new color attenuation parameters containing decryption information, and play each frame of the encrypted source. Since the password sequence generated in the decryption link of the specified player is consistent with the encryption link, the encrypted source can be correctly decrypted. In the case of playing on other machines or other theaters, the source color cannot be restored correctly due to the inconsistency between the decryption sequence and the encryption sequence. Therefore, according to the above steps, the video encryption and decryption playback technology based on multi-projector splicing and fusion is realized.

The invention includes a film encryption method based on multi-projector splicing and fusion, and a film decryption method based on multi-projector splicing and fusion. Only when the two methods are matched and used can the encryption and decryption operations of the film be completed, and a complete processing flow is realized. As shown in Figure 1, (1) Encryption process: Carry out parametric grid division of the target curtain and select the encryption area, call the player password generation software (Crypto++) on the designated target machine to produce the player's native password sequence, And convert it into a binary sequence, establish the corresponding relationship between the parameterized grid of the encrypted area and the binary sequence of the encrypted password, generate an encrypted mask watermark image, and generate an encrypted movie source in post-production (because the binary number of the encrypted sequence has been generated, so Generate an encrypted mask watermark image, and generate an encrypted movie source in post-production for remote processing); (2) Decryption process: This process runs synchronously when playing the movie, first run Crypto++ to generate a decrypted password and convert it into a binary sequence to generate a splicing The decoding configuration information is fused, and based on this, the binary sequence information is fused into the color transformation of splicing fusion playback, and decryption playback is completed together with color attenuation in the splicing fusion color transformation. If and only when the encrypted video source is played on the authorized machine, the video source can be correctly decoded; when played on other machines, the encrypted video source will not be correctly decoded. Thereby realizing the copyright protection to film source.

The video encryption method based on multi-projector splicing and fusion in the embodiment of the present invention includes:

Step A1, parametrically meshing the projection screen, and selecting an encrypted area.

Carry out parametric grid division for the target screen, as shown in Figure 2, take the ring screen as an example: divide the screen into (M+1)*(N+1) parameter grids according to the parametric equation. The parameter grid point coordinates on it: [i,j] (i=0,1,2,3...M; j=0,1,2,3...N). The coordinates of the point on the cylinder of the ring screen corresponding to the grid coordinates are: [i*Δθ, j*Δh]. In the present invention, the encrypted area is selected as the fusion area, and the parameter range corresponding to the fusion area is: i∈[i ₀ , i ₁ ]. In Figure 2, the grid of thin and thick lines is the parameterized grid of the target curtain, and the part of the thick line is the encrypted area and also the color fusion area;

Step A2, using encryption software to generate passwords on the target machine for the parameter grid of the encryption area.

Call Crypto++ password generation library, generate password C ₀ on the player, and convert password C ₀ into binary sequence C ₁ . The first (i ₁ -i ₀ ) N bits are selected, and the number of bits of each binary number corresponds to the fused grid whose ID (code bit) is the number of bits. The corresponding relationship between the binary sequence and the curtain parameter grid is shown in Figure 3, the code points are 1, 2, 3, 4, 5..., and the corresponding code values are 0, 0, 1, 1, 1...;

Step A3, converting the password generated in step A2 into a binary number, and selecting the first n digits to generate a video encryption mask.

As shown in Figure 3, according to whether the binary number D _i corresponding to each grid ID is 0 or 1, a spliced fusion encryption mask is generated, and the color RGB component color attenuation password E _i of the grid encryption mask corresponding to ID i on the mask map The generation method is shown in formula (1):

The generated encrypted mask image is a grayscale image with (i ₁ -i ₀ )N grids, and the grayscale value of each grid is determined to be 0.5 or 1 by the ID decay password E _i corresponding to the position.

Step A4, in the process of rendering and generating the projection film, superimposing the watermark mask to generate the encrypted film.

As shown in Figure 4, after the player (server) generates the password mask, use the watermark superposition program in AE (Adobe After Effects) to encrypt each frame of the film source to be kept secret. The encryption method adopts the method of multiplying the watermark and the original image. Through multiplication, the original film is partially encrypted in the encrypted area. If the grid in the encrypted area corresponds to the ID attenuation password: when E _i is 0.5, the color intensity of the grid part of each frame of the encrypted film source becomes half of that before encryption; while E _i is 1 At this time, the color intensity of the grid part of each frame of the film source after encryption is consistent with that before encryption. In this way, the encryption area of the encrypted video source generates an encryption effect in which the color light and shade changes.

The film decryption method based on multi-projector splicing and fusion of the present invention performs splicing, fusion and decryption synchronous operations on encrypted film sources during the playback link, and unifies the decryption process and the splicing and fusion process. The splicing and fusion software is used to divide the grid according to the parameters to perform geometric transformation and color fusion on each frame of the source image to form splicing and fusion.

For unencrypted film sources, the splicing and fusion program called in the present invention performs geometric transformation on the film source according to the shape of the screen and the relative position and posture relationship between the screen and the projector so that the projection part of each projector is perfectly aligned with the screen and other projections. The projection part of the projector is perfectly fitted to complete the function of the multi-projector splicing part of the film; at the same time, for the overlapping area of different projectors, the Alhpa transformation is performed on the colors of different projectors, that is: the color brightness is adjusted according to its distance from the non-fusion area The distance is attenuated, so that the color brightness of multiple projectors overlapped is consistent with the projection effect of a single projector, and the color fusion part of the multi-projector function is completed.

In the present invention, the geometric transformation part of the encrypted film source is completely consistent with the unencrypted film source, while the color attenuation and decryption are simultaneously performed in the color film change part. The effect of decryption is that only when the decryption splicing fusion program of the present invention is run on the player can it be correctly decrypted, and the encrypted film cannot be correctly decrypted and played when trying to play the encrypted film on other machines.

The film decryption method based on multi-projector splicing and fusion in the embodiment of the present invention includes the following steps:

Step B1, identifying the encryption area;

Step B2, calling the encryption software used when generating the password, and generating the same password as encryption for the parameter grid of the encryption area;

Step B3, converting the password generated in step B2 into a binary number, and generating splicing fusion decryption configuration parameters;

In step B4, the splicing and fusion software invokes the decryption configuration parameters, plays the encrypted video source, and performs decryption and playback.

In order to illustrate the decryption method of the present invention more clearly, the specific process is described again in conjunction with Fig. 5: first, when running the splicing and fusion player program, run the Crypto++ password generation program on this machine to generate the same password as in the encryption process ( If it runs on the specified player, the password is different for other machines), and converts the password into binary code. Based on the preset attenuation password generation method, the calculation formula of the color-enhanced password E′ _i is constructed, as shown in formula (2). For the grid whose encrypted password E _i is 0.5, the splicing and fusion program not only completes the normal color attenuation change, but also multiplies the color brightness by 2 according to the information that E _i is 0.5; and for the grid whose encrypted password E _i is 1 format, only the same color attenuation as that of unencrypted source playback is performed. In this way, the splicing fusion decryption process of the encrypted film source is completed.

And for the situation of trying to play this encrypted film source on other machines, because the password obtained by running Crypto++ on other machines is not consistent with the encrypted password, the correct decryption result will not appear. In the final playback display, some grid blocks are obviously darker than others, while others are brighter than others, and even highlight areas appear. Therefore, the encrypted video cannot be played correctly.

Fig. 6 is an effect diagram of each link of encryption and decryption. Among them, Fig. 6a is an effect diagram of a single frame of an unencrypted film source, Fig. 6b is an effect diagram of a single frame of an encrypted film source, and Fig. 6c is an effect diagram of a single frame of a decrypted film source.

For the situation where the same player is used to play in other theaters, since the geometric transformation part of the splicing and fusion invention program is calculated and set for the machine playback position of the specified film, so for other theaters, due to the different sizes of the screens, each projection The relative position and posture of the instrument and the screen are different, so running the same program will not get the correct splicing and fusion results.

The steps of the methods or algorithms described in connection with the embodiments disclosed herein may be implemented by hardware, software modules executed by a processor, or a combination of both. Software modules can be placed in random access memory (RAM), internal memory, read-only memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, hard disk, removable disk, CD-ROM, or any other Any other known storage medium.

Those skilled in the art should be able to realize that the method steps described in conjunction with the embodiments disclosed herein can be implemented by electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the possibility of electronic hardware and software For interchangeability, in the above description, the composition and steps of each example have been generally described according to their functions. Whether these functions are performed by electronic hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art may implement the described functionality using different methods for each particular application, but such implementation should not be considered as exceeding the scope of the present invention.

The term "comprising" or any other similar term is intended to cover a non-exclusive inclusion such that a process, method comprising a series of elements includes not only those elements but also other elements not expressly listed or also includes such processes, methods inherent elements.

So far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings, but those skilled in the art will easily understand that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art can make equivalent changes or substitutions to relevant technical features, and the technical solutions after these changes or substitutions will all fall within the protection scope of the present invention.

Claims (10)

1. A film encryption method based on multi-projector splicing fusion, is characterized in that, comprises the following steps: Step A1, parametrically meshing the projection screen, and selecting an encrypted area; Step A2, using encryption software to generate passwords on the target machine respectively for the parameter grid of the encryption area; Step A3, converting the password generated in step A2 into a binary number, and selecting its first n digits to generate a movie encryption mask; Step A4, in the process of rendering and generating the projection film, superimposing the watermark mask to generate the encrypted film. 2. The film encryption method based on multi-projector splicing and fusion according to claim 1, characterized in that, the method of "carrying out parameterized grid division to the projection screen, and selecting the encryption area" is as follows: Divide the projection screen into (M+1)*(N+1) parameter grids according to the parametric equation, where the coordinates of the parameter grid points are [i, j] (i=0,1,2,3 ...M;j=0,1,2,3...N); Select the fusion area as the encrypted area, and determine the parameter grid corresponding to the encrypted area. 3. The film encryption method based on multi-projector splicing fusion according to claim 2, characterized in that, said "convert the password generated by step A2 into a binary number, select its first n bits to generate a film encryption mask", Its method is: Convert the password generated by step A2 into a binary number; Based on the preset attenuation password generation method, calculate the grid encryption mask color RGB component color attenuation password _{E i} corresponding to the number i on the mask graph. 4. The film encryption method based on multi-projector splicing and fusion according to claim 3, wherein the preset attenuation password generation method is 5. the film encryption method based on multi-projector splicing fusion according to claim 3, is characterized in that, described " overlay watermark mask generates encrypted film ", its method is: Encrypt each frame of the film source to be kept secret through the watermark superposition program; the encryption method is the multiplication of the watermark and the original image. 6. The film encryption method based on multi-projector splicing and fusion according to any one of claims 1-5, wherein the encryption software is a Crypto++ password generation library. 7. A film decryption method based on multi-projector splicing and fusion, is characterized in that, comprises the following steps: Step B1, identifying the encryption area; Step B2, calling the encryption software used when generating the password, and generating the same password as encryption for the parameter grid of the encryption area; Step B3, converting the password generated in step B2 into a binary number, and generating splicing fusion decryption configuration parameters; In step B4, the splicing and fusion software invokes the decryption configuration parameters, plays the encrypted video source, and performs decryption and playback. 8. The film decryption method based on multi-projector splicing and fusion according to claim 7, characterized in that step B2 is performed when performing splicing and fusion playback. 9. The film decryption method based on multi-projector splicing fusion according to claim 8, characterized in that, said "convert the password generated by step B2 into a binary number to generate splicing fusion decryption configuration parameters", the method is : Convert the password generated by step A2 into a binary number; Based on the preset attenuation password generation method, calculate the grid encryption mask color RGB component color attenuation password E _i corresponding to the sequence number i on the mask graph, and generate the color enhancement password E′ _i . 10. The film encryption method based on multi-projector splicing fusion according to claim 9, characterized in that, the preset attenuation password generation method is The color enhanced password E′ _i is