EP3381009A1

EP3381009A1 - Method of processing a sequence of digital images, method of watermarking, devices and computer programmes associated therewith

Info

Publication number: EP3381009A1
Application number: EP16819593.1A
Authority: EP
Inventors: Félix Henry; Patrice Houze; Emilie SIRVENT-HIEN; Gaëtan LE GUELVOUIT
Original assignee: B Com SAS
Current assignee: B Com SAS
Priority date: 2015-11-24
Filing date: 2016-11-21
Publication date: 2018-10-03
Also published as: FR3044140B1; US20180357742A1; WO2017089689A1; FR3044140A1

Abstract

The invention relates to a method of processing a sequence of digital images with a view to its transmission to at least one client via a telecommunication network, said sequence being chopped into a plurality of groups of images. According to the invention, the images of a group are partitioned into spatial zones and the method comprises the following steps, implemented for a group of images, termed a current group -a) formation (E1) of a main group comprising the original images of the current group, partitioned into at least two predetermined spatial zones, collocated in the images of the current group and comprising at least one so-called watermarking zone -b) obtaining (E3) of a main binary train representative of a zone-wise coding of the main group formed, in which for a zone other than said at least one watermarking zone, the pixels of this main zone are not predicted by reference to pixels of the watermarking zone of an image of the group; -c) for a so-called watermarking zone: * formation (E4) of a secondary group of images of the same temporal dimension as the main group and of spatial dimensions equal to those of the watermarking zone; * insertion (E5) of a first value of an item of watermarking information into the secondary group formed; * obtaining (E6) of a first secondary binary train representative of the encoded secondary group including the first value of an item of watermarking information; -d) sending (E7) of the main binary train, and of the at least one first secondary binary train in the telecommunication network destined for at least one client.

Description

Method of processing a digital image sequence, tattooing method, devices and associated computer programs

1. Field of the invention

The field of the invention is that of the transmission of video content encoded in a communication network, in particular the transmission of video content intended to be digitally tattooed before delivery to a customer.

The invention may especially, but not exclusively, apply to tracking copy of a digital content.

2. Presentation of the prior art

Also known are tattooing techniques which consist in inserting a client code in a bit stream comprising coded data representative of a video content intended for a client, in order to "tattoo" the copy of the video content before delivery to the customer.

Among these techniques, it is considered in particular that of transmitting the client code by inserting the bits that form the code word in consecutive groups of images of the encoded stream.

In relation with FIG. 1A, there is shown a current image group GC of a digital image sequence Im, with m non-zero integer between 1 and M. Typically, such a group GC comprises N images, with N nonzero integer less than M, duration of 1 to 2 seconds, which corresponds to N = 25 or 50 images for an image rate of 25 images per second.

It is assumed that the tattoo information to be inserted into the segment is binary.

On the one hand, a first group G1 is formed in Ai1 in which the value T1 = 0 is inserted in the intensities of the image elements or pixels of the current group GC and the first group is encoded at A21. We obtain a first binary train TBTl.

On the other hand, a second group G2 is formed in A21 in which the value T2 = 1 is inserted into the intensities of the pixels of the current group GC and the second group is encoded at A22. We obtain a second TBT2 binary train.

The bit streams TBT1 and TBT2 obtained are stored in a memory M. For a given quality level, it is therefore necessary to provide an encoded version of the group Gl embedding a first symbol and a second version of the same group G2 boarding a different symbol. In the binary case, it is customary to use a version carrying the bit 0 and a version carrying the bit 1.

It is understood that at a point in the network on the path followed by the flow of data to the customer, a group assembly specific to the customer is made, to transmit the tattoo code that identifies it.

Figure 1B illustrates an assembly example for a client whose identifier IDCL is the symbol sequence T1T2T1T2. This identifier can be transmitted in the coded data of 4 consecutive image groups GC1, GC2, GC3 and GC4, the bit stream TBT1 (GCl) associated with GC1 carrying the value T1, the bit stream TBT2 (GC2) associated with GC2 carrying the value T2, the bit stream TBT1 (GC3) associated with GC3 carrying the value Tl and the bit stream TBT2 (GC4) associated with GC4 carrying the value T2.

Such an assembly can be implemented at the server which stores the bitstreams corresponding to different tattooed versions of the encoded groups or further downstream, for example at an intermediate equipment or in the client terminal. The article by Kopilovic et al, titled "Video-DNA: Large-scale server-side watermarking" published in the Proceedings of the 15th European Signal Processing Conference in 2007, describes several approaches for tattooing coded data representative of audiovisual content. . In particular, it describes an "all-server" approach whereby the server is responsible for the assembly for each client and sends as many bitstreams as clients to the network, an "all-customer" approach where the client equipment performs all the operations tattoo, the same binary train being sent to all customers. This second approach requires significant computing capabilities on the client side. An intermediate approach is to transmit the two current tattooed group versions with different values to the client who is responsible for the final assembly. The transmission network is then loaded but the assembly does not require significant computing capacity.

With a view to their transmission to the customer (s), the bit trains relating to a group of images are encapsulated in a transport container for example specified by ISO / IEC 14496-12 for the transport of streams. Multimedia, known as ISOMBFF (for "ISO Base Media File Format"). An extension of this standard provides for the possibility of transporting a main bit stream comprising coded data representative of a group of images in which a first tattoo information value has been spread out and at least one variant of this bit stream. (for "variant", in English) representative of the same group of images, in which a second tattoo value has been spread

There is also known a technique for transmitting video content, called HAS (for "Http Adaptive Streaming" in English) which consists of storing server side, in the form of time segments; several encoded versions of the same video content, corresponding to different levels of quality. A client who wishes to receive content, first requires a description file, MPD or Manifest type, server-side available streams and orders the server the delivery of the quality level segment adapted to the network transmission conditions it has. It can change version over time depending on the evolution of these conditions. This technique is particularly described in the article "Dynamic Adaptive Streaming over http (DASH) - Standards and Design Principles", by Thomas Stockhammer, published in Proceedings of the "ACM Conference on Multimedia Systems, February 2011, pages 133- 144.

In such a context of adaptive transmission of encoded audiovisual content, the main bit stream comprising a first tattoo information value and its variant or variants containing at least one other tattoo information value are segmented temporally. For each time segment, a customer orders which of the available qualities best suits his resources. The server responds by transmitting to it the main bitstream corresponding to the selected segment and at least one variant. A customer-specific tattoo can be made at a point in the path followed by the binary trains, more or less close to the end customer.

3. Disadvantages of prior art

A disadvantage common to all these approaches is an additional cost of resources, in terms of calculation, storage and bandwidth, since in any case it is necessary to have two complete encoded versions of each segment at each level of available quality. The size of the data to be processed, stored and transmitted is therefore potentially doubled.

4. Objectives of the invention

The invention improves the situation.

The invention particularly aims to overcome these disadvantages of the prior art.

More specifically, an object of the invention is to propose a solution that is more economical in coding / storage / transmission resources, while remaining robust and adaptive to the different needs of customers. Another object of the invention is to propose a solution that is compatible with current or future standards for transporting bitstreams in a communication network.

5. Presentation of the invention

These objectives, as well as others that will appear later, are achieved by means of a method of processing a sequence of digital images for transmission to at least one client via a telecommunications network, said sequence being cut into a plurality of groups of images.

According to the invention, the method is particular in that, the images of a group being partitioned into spatial zones, it comprises the following steps, implemented for a group of images, called current group:

a) forming a main group comprising the original images of the current group, said images being partitioned into at least two predetermined spatial zones, located at the same spatial coordinates, or collocated, in the images of the current group and comprising at least a so-called tattoo area;

b) obtaining a main bit train representative of a zone encoding of the images of the main group formed, in which for an area other than said at least one tattooing zone, the pixels of this zone are not predicted by reference to pixels in the tattoo area of an image of the group;

- c) for a said tattoo area:

o formation of a secondary group of images of the same temporal dimension as the main group and of spatial dimensions equal to those of the tattooing area;

inserting a first tattoo information value into the formed secondary group;

obtaining a first secondary bit stream representative of the images of the encoded secondary group including the first tattoo information value;

d) transmission of the main bitstream, and the at least one first secondary bitstream in the telecommunication network to at least one client.

Unlike the solution of the prior art, which duplicates the bitstreams comprising the coded data of a segment of the image sequence in as many versions as possible values of the tattooing information, the invention proposes to limit the duplication of the encoded data for the same segment, by tattooing only a subset of the pixels of the images of this segment.

According to the invention, at least one secondary group of images is constructed whose spatial dimensions are those of the tattooing area and the temporal dimensions of those of the current group. We obtain thus a sequence formed of "thumbnails" of dimensions smaller than that of the images of the original group. Within the pixel intensities of these "thumbnails", a value of the tattoo information is inserted. The secondary group is then encoded as a small independent sequence, in a so-called secondary binary train. The main group, whose images are partitioned in spatial zones, collocated in the group images, is encoded by spatial area, so that from the bit stream obtained, it is possible to access the coded data representative of the tattooing area and replace them with others of the same spatial and temporal dimensions, such as for example that of a secondary group. With the invention, the main bit stream and the secondary bit stream (s) obtained for the current group are independent and recomposable into a bit stream including the desired tattoo information value for example for a particular customer. A secondary bitstream, because it encodes spatial areas smaller than those of an image in the main group, requires less computing resources to be processed, occupies less memory space, and requires fewer network resources to to be transmitted as the main bit stream.

The invention thus exploits by adapting the encoding functionality by spatial area to limit the extra cost generated by the tattooing of video content. The invention thus makes it possible to save storage and transmission resources, which is all the more important as the tattooed space zone is smaller. According to an advantageous characteristic of the invention, the method further comprises a step of inserting a second tattooing information, distinct from the first, in the tattooing zone of the main group formed.

Suppose the tattoo information is binary and the tattoo code of a client is formed by concatenating a number of tattoo information or symbols. According to the invention, the main bitstream carries a first value, for example 0 and the secondary bitstream a second value distinct from the first, for example 1. Because of the encoding by zone as specified by the invention , it is possible to extract the tattoo area comprising the 0 of the main segment and replace it with the tattoo area of the secondary segment including zero. The invention therefore provides, from the main bitstream and a secondary bitstream, what to construct for the current segment, the bitstream comprising the symbol corresponding to the target client.

One advantage of this solution is to be very resource efficient. According to another aspect of the invention, the method further comprises the following steps: for a tattoo area:

forming a second group of secondary images of the same temporal dimension as the main group and of spatial dimensions equal to those of the tattooing area;

insertion in the secondary group formed by at least a second tattoo information value;

obtaining at least a second secondary bit stream comprising encoded data representative of the secondary group including the second value of tattoo information; transmitting the at least one second secondary bit stream to at least one client.

This alternative is to transmit the first and at least the second tattoo value in secondary bitstreams corresponding to a tattooing area. It has the advantage of being generic in the sense that it does not require tattooing at the source of the main gear. It thus allows a pre-routing of generic bitstreams in the network, for example in multicast mode and a specific processing for each client as far downstream as possible. According to yet another aspect of the invention, the step of forming the main group comprises replacing the original intensities of the at least one tattooing area with predetermined intensity values.

Since the original values of the image group have been replaced in the tattoo area by predetermined values, a client can not obtain the complete video content from the single main bit stream, which is amputated by part of the content. An advantage of this embodiment is to be more secure.

According to another aspect of the invention, the predetermined values are invariable values.

An additional advantage is that the spatial zone corresponding to the tattooing area in the main segment is inexpensive to encode with an encoder implementing a prediction of pixels of a current image from pixels of an already processed image.

According to another aspect of the invention, the step of forming a secondary group for a tattooing area comprises extracting intensity values of the pixels from the tattooing area in the original images of the current group.

Thus, the secondary bitstreams encode the original video content into the tattoo area, in which a tattoo information value has been inserted. One advantage is that the recomposition of the main and secondary bitstreams by replacing the coded data concerning the tattooing area of the main bit stream with that of a secondary train comprising information of tattooing, leads to reconstructing the entire video content by recomposition of the binary trains received, without loss of relevant information.

According to yet another aspect of the invention, the method comprises a step of choosing said at least one tattooing zone among the partitioned zones. The invention thus allows the possibility of changing tattooing zone from one segment to another. One advantage is to change the location of the tattoo area when processing a new segment, for example to hide relevant content. One can consider taking into account semantic information to choose the tattoo area, for example to follow an object or character that moves in the image. In yet another aspect of the invention, the method further comprises a step of determining an enlarged tattoo area in the main group images, including the tattoo area and a predetermined width border around said area. The zone encoding comprises a step of applying a filter of size less than or equal to the predetermined width at the borders of the zones of the images of the main group and for an area of an image other than said at least one tattooing area. , the prediction of the pixels of the zone does not refer to the pixels of said at least one enlarged tattooing area of another image of the group.

In this way it is ensured that the filter does not change the rest of the image with information contained in the tattoo area, which is intended to be replaced by recomposition.

According to yet another aspect of the invention, the partitioning implemented in the main group forming step comprises at least a first and a second tattooing area and the step of inserting at least a first information item. Tattooing in the secondary group includes inserting a first tattoo information into the first area and a third tattoo information into the second area. This third tattooing information may take the first or second value in the binary case. An advantage of this embodiment of the invention is that at least two symbols can be transmitted in the same segment and a tattoo code word comprising several symbols can be transmitted over a time period twice as short. Thus, the transmission of the content is made more robust to a capture of a short extract of the sequence.

The method that has just been described in its various embodiments is advantageously implemented by a device for processing a sequence of digital images for transmission to at least one client via a telecommunications network, said sequence being cut into a plurality of groups of images. Such a device being particular in that, the images of a group being partitioned into spatial zones, it comprises the following units, which can be implemented for a group of images, called the current group: a) formation of a main group comprising the original images of the group current, said images being partitioned into at least two predetermined spatial zones, located at the same spatial coordinates, or collocated, in the images of the current group and comprising at least one so-called tattooing zone;

c) for a said tattoo area:

o formation of a group of secondary images of the same temporal dimension as the main group and of spatial dimensions equal to those of the tattooing area; inserting a first tattoo information value into the formed secondary group;

obtaining a first secondary bit stream representative of the images of the encoded secondary group including the first tattoo information value; d) transmission of the main bitstream, and the at least one first secondary bitstream in the telecommunication network to at least one client.

Correlatively, the invention also relates to a method of tattooing a sequence of digital images transmitted in a telecommunication network to at least one customer, said sequence being divided into groups of images, characterized in that said method comprises the following steps, implemented for one group, said current group: - preliminary obtaining a representative value of at least one tattoo information, said customer tattoo information, to be inserted in the current group intended for audit at least a customer ;

receiving a main bitstream comprising coded data representative of a main group, formed from the original group images partitioned in at least two predetermined spatial areas, collocated in the group images and comprising at least one area so-called tattooing, the coded data having been obtained by means of a spatial zone encoding of the main group, in which the prediction of the pixels of an area of an image of the group other than said at least one tattooing area. is not made by reference to the pixels of said at least one tattooing area of said image or other image of the group; obtaining information relating to a tattoo information value inserted in the current group of the received primary bitstream;

When the value obtained is not equal to the tattoo information of the customer, the method further comprises:

o for a said tattoo area:

Receiving at least a first secondary bit stream comprising encoded data representative of a secondary image group, wherein a tattoo information value equal to the customer's tattoo information has previously been inserted, said group secondary being of the same temporal dimension as the current group and of spatial dimensions equal to those of the tattooing zone;

Composing a bit train intended for auditing at least one client, by replacing the coded data associated with the at least one tattooing area in the main group with the coded data of the secondary bitstream.

Before delivering the video content to the customer, the bit streams are recomposed to insert the tattoo information or adapted to the recipient customer.

The method according to the invention can be implemented at different points of the path followed by the main and secondary bitstreams. For example, at the client level (set top box), the composition will be customer-specific and a tattoo to uniquely identify it will be inserted into one or more groups in the sequence. The recomposed bitstream will then be presented to the decoder.

Further upstream in the network, it is possible to envisage a partial composition, implemented by an intermediate network equipment (middle box), for example a server or a DSLAM type equipment serving a certain number of clients, and relating to the information tattooing common to many of them. In this case, the recomposed bitstream is transmitted to the customer (s) instead of the primary and secondary bitstreams.

It can also be implemented directly by the server for a point-to-point delivery, dedicated to a particular customer. According to this option, it is a binary train specifically recomposed for the client that is sent by the server.

The method just described is advantageously implemented by a tattooing device of a sequence of digital images transmitted in a telecommunications network to at least one customer. The sequence is divided into groups of images. The device according to the invention comprises the following units, which can be implemented for one group, said current group: prior obtaining of a representative value of at least one tattooing information, said tattooing information of the client, to be inserted into the current group intended for auditing at least one client;

receiving a main bit stream comprising encoded data representative of a main group, formed from the current group-origin images partitioned into at least two predetermined spatial areas, collocated in the group images, and comprising at least one so-called tattooing area, the coded data having been obtained by means of a spatial zone encoding of the main group, according to which the prediction of the pixels of an area of an image of the group other than said at least one zone of tattooing is not done by reference to the pixels of said at least one tattooing area of said image or other image of the group;

obtaining information relating to a tattoo information value inserted in the current group of the received primary bitstream;

o for a said tattoo area:

The invention also relates to communication equipment adapted to receive one or more bitstreams comprising coded data representative of a sequence of images from a server equipment and to transmit them to one or more client equipment recipients and the device tattoo that has just been described.

The invention also relates to a client equipment capable of receiving one or more bitstreams comprising coded data representative of a sequence of images from a server equipment, said equipment comprising a decoder capable of decoding the received bitstreams and the tattoo device which has just been described. Correlatively, the invention relates to a signal carrying encoded data representative of a sequence of digital images for transmission to at least one client via a telecommunications network, said sequence being divided into groups of images, characterized in that for said group, said current group, said coded data comprises: - a main bit stream comprises encoded data representative of the images of a main group formed by partitioning the original images of the current group into at least two predetermined spatial areas, located at the same spatial coordinates, or collocated, in the images of the main group and comprising at least one so-called tattooing zone, said zones having been obtained by zone encoding of the main group, according to which for an area other than said at least one zone tattoo, the pixels in the area are not predicted by reference to pixels in the tato image of the main group;

for said at least one tattoo area:

at least one first secondary bit stream comprising encoded data representative of the images of a secondary group of images, of the same temporal dimension as the main group and of spatial dimensions equal to those of the tattooing zone, in which a first value representative of a tattoo information has been inserted;

said bit streams being intended to be received by a device able to determine at least one tattoo information value to be associated with at least one client, and, when the value of tattoo information of the customer is equal to the first information tattooing, to recompose, from received bitstreams, a bit stream intended for said at least one client, by replacing the coded data of the main bitstream associated with said at least one tattooing zone in the main group, with the coded data of the secondary binary train.

According to one aspect of the invention, for said at least one tattooing area, a second tattooing information value having been inserted in the tattooing area of the main group images, the main bit stream comprises coded data representative of the images of the main group and the second tattoo information value.

In this way, in the case of binary tattoo information, two bitstreams are sufficient to be able to construct all possible values of client identifiers.

The invention also relates to a computer program comprising instructions for implementing the steps of a processing method as described above, when this program is executed by a processor. The invention also relates to a computer program comprising instructions for implementing the steps of a tattooing method as described above, when this program is executed by a processor.

These programs can use any programming language. They can be downloaded from a communication network and / or recorded on a computer-readable medium.

The invention finally relates to recording media, readable by a processor, integrated or not integrated with the treatment device and the tattooing device according to the invention, possibly removable, respectively storing a computer program implementing a method. process and a computer program implementing a tattooing method, as described above.

6. List of figures

Other advantages and characteristics of the invention will emerge more clearly on reading the following description of a particular embodiment of the invention, given as a simple illustrative and nonlimiting example, and the appended drawings, among which: FIGS. 1A and 1B (already described) show schematically a method for transmitting a digital image sequence comprising tattooing information according to the prior art; Figure 2 schematically shows a method of processing a sequence of digital images according to a first embodiment of the invention; FIGS. 3A and 3B illustrate two examples of spatial zone partitioning of images of a time segment of a sequence of digital images implemented by the processing method according to the invention; FIG. 3C illustrates an example of a region encompassing a tattooing zone, implemented during the encoding of the main image group according to the invention;

Figure 4 schematically shows the steps of a method of tattooing a sequence of digital images according to the first embodiment of the invention; Figure 5A schematically illustrates an example of processing a digital image sequence by a server equipment according to the first embodiment of the invention; Figure 5B schematically illustrates an exemplary implementation of the tattooing method according to the first embodiment of the invention; Figure 6A schematically illustrates an example of segmentation of bitstreams from the processing method according to the invention by an intermediate equipment; Figure 6B schematically illustrates an example of combined implementation of the tattooing method according to the first embodiment of the invention and a segmentation of bitstreams by an intermediate equipment; Figure 7 schematically shows a method of processing a sequence of digital images according to a second embodiment of the invention; Figures 8A and 8B illustrate two examples of tattoo area choice in a current segment according to the invention; Figure 9 schematically shows the steps of a method of tattooing a sequence of digital images according to the second embodiment of the invention; Figure 10A schematically illustrates an exemplary implementation of the method of processing a sequence of digital images by a server equipment according to the second embodiment of the invention; ; Figure 10B schematically illustrates an exemplary implementation of the method of tattooing a sequence of digital images by an intermediate or client equipment according to the second embodiment of the invention; and FIGS. 11A and 11B schematically show examples of a hardware structure of a processing device and a tattooing device of a digital sequence according to the invention.

DESCRIPTION OF A PARTICULAR EMBODIMENT OF THE INVENTION The general principle of the invention rests first on the partitioning in spatial zones of the images of a current group of images of a sequence of digital images comprising at least one tattoo area. It also includes the insertion of tattoo information into the tattoo area and the independent encoding of one or more tattooed versions of that tattoo area, so that its coded data can be easily inserted into a train main binary of the current group, before its delivery to a client and without transcoding operation.

In the remainder of the description, a sequence of images divided into consecutive groups of images, for example of duration of 2 seconds, comprising 50 images, is considered. A group of images may or may not correspond to a GoP (for "Group of Pictures") in the terminology of video compression standards such as HEVC for "High Efficiency Video Coding" or AVC (for "Advanced Video Coding") by example.

It should be noted that the invention applies to any type of image sequence and in particular to a sequence of images obtained from an immersive video, that is to say from a video recording of a video. real-world scene where images are captured in multiple directions at the same time, around a central point, corresponding to the user's position. During the viewing, the acquired images are projected for example on a cube from the center of which the user can control the angle of view and the speed of movement. In this case, an image (for "frame", in English) of the sequence within the meaning of the invention comprises the six unfolded faces of the cube.

In relation to FIG. 2, the steps of the method of processing a sequence of images according to a first embodiment of the invention are described.

In particular, a current image group GC of the image sequence is considered. During a step E0, each of its images is partitioned into at least two spatial zones, according to a predetermined partitioning. At least one of these areas constitutes a tattoo area ZT.

A priori, any type of spatial partitioning can be considered. However, in practice, it must be authorized by the coding scheme of the image sequence.

In connection with FIG. 3A, there is shown an example of partitioning in two slices SU, SI2 (for "slices", in English), as specified in the AVC standard, by Iain E. Richardson, in section 5.6 of the 'The H.264 Advanced Video Compression Standard', 2nd Edition, ISBN: 978-0-470-51692-8), published in April 2010 by Wiley. These two slices can be encoded independently of one another according to a particular mode of the AVC standard.

In this example, the tattooing zone ZT1 corresponds to the slot SU, for which it is possible to generate a bit stream specific to this zone, comprising encoded data independent of those of the current group GC.

In connection with Figure 3B, there is shown a second example of partitioning images of the current group of images, in tiles (for "tiles" in English). This partitioning is described in the HEVC specification by Sze, Vivienne, Budagavi, Madhukar, Sullivan, Gary J. (Eds.), Titled "High Efficiency Video Coding (HEVC) Algorithms and Architectures," ISBN 978-3-3199. -06895-4, DATE, as well as an independent encoding of each tile.

In this example, the tattoo area ZT is the TI4 tile. This tile can be the subject of an independent encoding and the construction of a specific bit stream. During a step El, a main group GP is formed from the partitioned current group. This main group has the same temporal and spatial dimensions as the current group. The information, in particular the intensity, carried by the elements of these images, pixels or voxels, is unchanged with respect to the current group in the spatial zones other than the tattooing area ZT.

Regarding the ZT tattoo area, several options are envisaged:

either the same intensity information is preserved as in the current group;

or the original values of this intensity information are replaced by determined values, for example invariant on all the images of the main group. According to the first embodiment of the invention illustrated in FIG. 2, the same information is preserved in the tattooing zone of the main group as in the current group. At this point, the main group is identical to the current group.

During a step E2, tattooing area IT2 is inserted into the tattooing area ZT of the main group SP. This tattoo information can be binary. or n-aire. In Figure 2, this step has been shown schematically by a dotted box, to indicate that it is not essential to the implementation of the invention. An alternative, that no tattoo information is inserted into the main bit stream will be presented in connection with Figure 7.

The insertion of the tattoo information is done according to a method known to those skilled in the art, for example that described in the article by Cox et al, entitled "Secure Spread Spectrum Watermarking Multimedia", published in IEEE Trans. on Image Processing, 6, 12, pp 1673-1687, in 1997. This method relies on the use of a spread spectrum function to transform a binary symbol into a sequence to be added to the elements of the image sequence. in the space or frequency domain (these elements can be pixels, or coefficients of a frequency transform DCT type for Discrete Cosine Transform, or DWT for Discrete Wavelets Transform (Discrete Cosine transform) Wavelet Transform ", in English.).

Let I be the vector representing the set of m elements that we wish to tattoo, coming from the zone ZT. In this embodiment, it is the set of coefficients resulting from the frequency transform of the images of a group of images.

A sequence denoted G is generated from a pseudo-random generator of length m. The elements of this sequence G must follow a Normal distribution centered in 0. The tattoo of the bit b in Ii is then given by the formula (1): I [j] + a. G [j] if b = 1, (1)

I [j] - a. Gi [j] if b = 0, for all j between 1 and m.

The factor a> 0 is a weighting that can be used to adjust the tradeoff between the strength of the brand and its visibility.

The reading of the tattoo symbol from the image J is given by the formula (2): b = 0 siΣf _{= 1} JD] - G [j] <0, (2)

bi = 1 otherwise.

For example, consider a group of images of dimensions 1080p, which corresponds to 1920 x 1080 pixels, which is divided into 9 identical spatial areas. If the central area is chosen solely as a tattoo area, the tattoo information will be spread over the 640 x 360 pixels of the tattoo area of the images of the group of images considered.

During a step E3, the main group of images is encoded according to a zone encoding technique, known per se. This encoding by spatial area can be advantageously achieved for example by implementing a so-called tile encoding technique, described in the specifications of the HEVC standard by Sze, Vivienne, Budagavi, Madhukar, Sullivan, Gary J. (Eds.) , titled High Efficiency Video Coding (HEVC) Algorithms and Architectures, ISBN 978-3-319-06895-4, DATE.

Slice-type spatial zone encoding is also described in the AVC standard, by Iain E. Richardson, in "The H.264 Advanced Video Compression Standard," 2nd Edition, ISBN: 978-0-470. 51692-8, DATA. A property of a slice / tile is to be decodable independently of other tiles in the current image, because the encoding of a tile does not introduce dependency with pixels of other tiles of the current image.

Also known is a technique of imposing constraints on a tile to make an independently decodable video stream and recomposable with other tiles to form a new video stream. This technique is described by Christian Feldmann, Christopher Bu Ma, Bastian Cellarius, in the document titled "Efficient Stream-Reassembling for Video Conferencing Applications Using Tiles in HEVC", MMEDIA 2013, in the Proceedings of the conference "The Fifth International Conferences on Advances in Multimedia ", Pages 130 to 135, in April 2013. The constraints to be applied are on the one hand, to have a tile cutting structure that is the same on the sequence of images concerned, and secondly, to encode these tiles by making sure that blocks of pixels contained in a tile are predicted only by pixels contained in that tile or pixels belonging to a tile located at the same spatial coordinates in another image of that series.

According to the invention, it is imposed as a particular constraint the fact of not allowing any prediction of elements or blocks of elements contained in spatial zones of an image of the main image group other than the tattooing zone in the same area. image or in a previously processed image. In this way, the coded data contained in the tattooing area may be modified, for example replaced by others without impact on the coded data of the other spatial areas of the main image group. Advantageously, the prediction of elements or blocks of elements contained in distinct spatial zones of the tattooing zone is forbidden by pixels contained in a region more broadly encompassing the tattooing zone. Indeed, it is known in the HEVC standard that when an image is subdivided into tiles, a reduction filter of the discontinuities is applied along the boundaries of the blocks, and therefore in particular along the tile boundaries. Such filtering is described for example in the document by Norkin et al entitled HEVC Deblocking Filter, published in IEEE Transactions on Circuits and Systems for Video Technology, Vol. 22, no. 12, December 2012. When HEVC compliant filtering is applied, the four rows of pixels on either side of the tile boundary take on new values that depend on the value of the pixels located on the tile. other side of the border before filtering. In connection with Figure 3C, there is shown an example of RE region encompassing the tattoo area ZT. It includes the tattoo area and a predetermined width margin around this area. The prediction of pixels outside the ZT tattooing area is prohibited by pixels in the RE region which comprises the pixels of the ZT zone and the 4 rows of pixels immediately adjacent to ZT. Indeed, the pixels located in the region RE are likely to take a modified value when the content of the tattoo area ZT is modified to adapt to the tattoo information, which would introduce an error in the prediction. Prohibiting this prediction thus makes it possible to avoid propagating prediction errors that would be detrimental to the quality of the reconstructed video.

The intensity information of the tattoo area and the IT2 tattoo information inserted therein are therefore encoded in the same TBP bit stream as the other areas of the main image group, but independently.

For example, the coded data representative of the tattooing area in the consecutive images of the main image group can be placed after the coded data representative of the other spatial areas of the other images of the main image group, for example at the end of the bitstreams comprising the coded data of the main group. In particular, a specific signaling is implemented to allow identification of the coded data corresponding to this tattooing area, without requiring a decoding of the data. This signaling may take the form of a start code, that is to say a sequence of bits known a priori, which serves to mark the beginning of the data corresponding to a tile. Alternatively, it may also take the form of length information, including the number of bits to count from the beginning of the data of the segment to arrive at the beginning of the data associated with the tile.

An example of signaling is for example already specified in the extension of the ISO BMFF standard, already mentioned, to indicate the positioning of the coded data of the main bitstream to replace those of a variant. During a step E4, a group of secondary images GS is formed from the intensity information contained in the tattooing area ZT of the current group GC. This secondary group has the same temporal dimension as the current group and the same spatial dimensions as the tattoo zone ZT. Examples of secondary groups formed from the common group are shown in Figures 3A and 3B, already described. Advantageously, the intensity information of the elements of the tattoo zone is extracted.

ZT of each of the images of the current group and they are copied into those of the secondary group GS. In this way, when the coded representative data of the secondary group GS is inserted in place of that of the tattooing zone of the main group, it will be possible to recompose a complete bit stream of the current group, without loss of useful information. Of course, one can also choose predetermined intensity values, for example invariable from one image to another of the secondary group. These invariable intensities, which are inexpensive to encode, will contribute to producing a small bit stream and thus save on computing, storage and bandwidth resources.

In E5, tattoo information IT1 is inserted into the images of the secondary group thus formed, for example with the method previously mentioned for step E2. It is assumed that IT1 does not have the same value as IT2. In the case of tattoo information of binary type, if for example IT2 = 1, then IT1 = 0 and vice versa.

In the case of information of the n-ary type with n> 2, it is understood that it will be necessary to provide n-1 versions of the secondary group. In E6, the images of the secondary group GS are encoded, using the same encoding scheme as for the main group. By the same encoding scheme, we mean an encoding conforming to the specifications of the same standard, so that the same decoder can decode the main and secondary bitstreams and we also make sure to configure the encoder so as to obtain an encoding quality equivalent to that of the main group. A TBST1 binary train representative of the secondary group containing the IT1 tattooing information is obtained.

In E10, the bitstreams obtained are formatted for transmission via a telecommunications network and the formatted bitstreams are transmitted. This formatting or encapsulation consists in placing the bitstreams in one or more containers. Such containers include a header in which information about the description of the bitstreams transported.

For example, these bitstreams can be transported in MPEG-2 TS (for Transport Stream in English) format, specified in standard ISO / IEC 13818-1, or ITU-T Rec. H.222.0, or the ISOBMFF format already cited. The steps E1 to E7 of the method are then repeated for successive groups of temporal images of the image sequence. Tattoo information can be inserted in all successive image groups or only in some of them. For a next segment, it is possible to choose to insert the same tattoo information IT1, IT2 in the main image group and in the secondary group as in the previous image group. According to one variant, it is possible to change the inserted value from one current group to another, for example to form, using the tattoo information successively inserted into the time groups, the sequence corresponding to the tattoo identifier associated with a particular customer.

One can also choose to insert tattoo information on a number of groups of images higher than the number of information needed to form the tattoo identification sequence of a client. An advantage of repeating the tattoo information sending throughout the image sequence is to ensure that the tattoo can be made from an extract of the sequence, provided that it includes enough groups of tattoos. temporal images.

According to the first embodiment of the invention, an exemplary implementation of which is illustrated in FIG. 5A, an SV server forms and transmits, in the telecommunications network, to one or more clients, at least two bitstreams: A TBP master bitstream comprising coded data representative of groups of images of the sequence of images to be delivered to one or more clients. In a group of images, IT2 tattoo information has been inserted in the middle of the intensity information of at least one tattooing area of the images of the group. Zone coding has been applied to the temporal image group so that the coded data representative of the tattooing area of the images of the group and those representative of the remainder of the images are independent of one another; at least one secondary bit stream TBST1 comprising coded data representative of a secondary group comprising "thumbnails" of equal dimensions those of the tattoo area and, for each image, the intensity information of the tattoo area in the original group of images. In the "thumbnails" of this group has been added IT1 tattoo information distinct from IT2. The "thumbnails" of the secondary group were encoded, using a coding scheme compatible with that used for the main group.

If the tattoo information is n-ary with n> 2, then n-1 secondary bitstreams can be transmitted. As a variant, it is also possible to define several distinct tattooing zones in the images of a group or to transmit the n possible values on n successive segments.

Primary and secondary bit streams are encapsulated in one or more containers

CTR.

According to a first option, illustrated by Figure 5A, each bit stream is transported independently of the other or in its own container.

According to a second option, not shown, the bitstreams are multiplexed before encapsulating them in one and the same container and transmitting it on the communication network.

According to a third option, not shown, combinable with the first or the second, the bitstreams are segmented in the sense of an adaptive transmission standard, such as DASH, already cited for example, before their encapsulation in one or more containers. In this context, the same container can encapsulate segments corresponding to the same group of images, and encoded at different levels of quality.

According to a fourth option, illustrated by FIG. 5B and combinable with the first or the second option, the bitstreams are not segmented at the SV server which implements the processing method according to the invention. They are transmitted in unsegmented form to an intermediate equipment EQ placed at break of the data streams. This equipment is in charge of segmenting them for delivery to customers, for example in adaptive transmission mode. The interest is to realize a part of the transmission path in a non-specific transport mode, in a generic configuration and to specify the bitstreams as far downstream as possible. It will be understood that in this case, the client requests the segments from this intermediate equipment EQ, rather than from the server equipment SV.

In relation to FIG. 4, the steps of a method of tattooing a digital image sequence intended for at least one client, according to a first embodiment of the invention, are now described. This process can be implemented within different equipment on the path followed by the primary and secondary bitstreams to an end customer. For example, it can be implemented at the level of a client equipment, for example a tablet or a laptop or a set-top box, in front of the decoding of the sequence. 'images, or in an intermediate equipment, type server or router, which serves several customers.

A current image group GC of the digital image sequence to be tattooed is considered for delivery to a client. This client is identified by a tattoo identifier comprising a sequence of B tattoo information, with B non-zero integer.

During a step T1, the value of the tattooing information, for example a binary value, to be inserted into the current group is obtained for at least one client. For example, this ITCL information is equal to IT1. For example, the equipment that implements the tattooing process has previously stored in memory, on the one hand the tattoo information sequence that forms the customer's tattoo identifier and on the other hand the tattoo information already inserted in previous time segments. This is to determine the value of the next ITCL tattoo information to be sent to the client to form the sequence of the customer's tattoo ID.

For example, it is assumed that it is the i ^th bit of the tattoo identifier IDTCL of the client which comprises B, a non-zero integer, for example equal to 20, which corresponds to more than a million of possible identifiers.

In T2, at least the main bit stream TBP, corresponding to the current group GC, is received. If the TBP master bitstream has previously been multiplexed to one or more secondary bitstreams before being encapsulated in a transport container, all bitstreams are necessarily received in this step.

In T3, information about a tattoo information value inserted into the received TBP master bit stream is obtained. For example, if the tattoo information is binary, we get 0 if bit 0 was inserted in the current group, 1 if bit 1 was inserted in the current group and 2 if no bit was inserted into the current group. current group. For example, the equipment that implements the tattooing process has previously obtained the information that the main bit stream carries the value IT1 and the secondary bit stream carries the value IT2. As a variant, this information is indicated in the header of the container of the main bit stream TBP. Advantageously, a field of the transport container of the binary train or trains is inserted, a "flag" type information signaling that tattooing information has been inserted into the current time segment and complementary fields including the tattoo indications, such as for example, the value of the tattoo information inserted and the tattoo area where it was inserted.

For a secondary bit stream comprising the coded data of a spatial area of the images of a segment, the additional information further comprises dependency information with the main bit stream, so that the tattooing device knows how to recompose the train full binary from the main and the secondary.

A known file format or transport container, such as ISOBMFF, provides zones ("free boxes") for recording metadata of this type.

In the case of an MPEG-2 TS transport container, this dependency information will advantageously be inserted in a "NAL Unit" sub-container (NALU) intended to transport metadata or coding parameters. We distinguish the parameters of type:

SPS (for "Sequence Parameter Set", in English), which, according to the HEVC standard, are associated with a sequence of images,

PPS (for "Picture Parameter Set") which are associated with an image (for example, a parameter indicating whether the image is encoded inter or intra), and

SEI (for "Supplemental Enhancement Information"), which includes parameters that are not essential for decoding, but which may be useful (for example, a post-processing filter).

These NALUs are called "non VCL" (for "Video Coding Layer" in English) because they do not carry video data. For example, the zone encoding information is inserted into the SPS and PPS fields and information about a tattoo area, inserting a tattoo information value into that zone, and the dependency. from a secondary binary train to a tattooing area of the secondary train are recorded in the SEI field.

In T4, it is determined whether a tattooing area of the current group contains in the main bit stream the tattoo information value contained intended for the customer.

If this is the case, the TBP master bit stream can be transmitted to the client without modification. Otherwise, it implements, for the tattooing zone considered, a T5 receiving step TBST1 secondary bit stream containing the desired tattoo information.

In T6, a new bitstream is composed by replacing the coded data of the main bitstream corresponding to the tattoo zone ZT with those of the secondary bitstream TBST1. We thus obtaining for the current group a bit stream TBCL integrating the tattoo information value intended for the client CL.

This bit stream TBCL specific to the client CL is transmitted to the client in a transport container, for example in accordance with one of the MPEG2 TS or ISO BFF standards already mentioned. According to a first option, illustrated in FIG. 5B, there is shown an intermediate equipment EQ implementing the tattooing method according to the invention. This equipment may be intermediate, or the SV server or the end customer. This equipment implements the tattooing method according to the first embodiment of the invention.

It receives at least the TBP master bit stream and, depending on the ITCL tattoo information to be transmitted to the client CL, decides whether or not to receive (process) the secondary bit stream TBST1.

In this example, it is considered that the tattoo information contained in the group considered the main bit stream is not that for the client CL.

A composition operation is therefore implemented to replace the coded data of the tattoo zone ZT with that of the secondary bit stream TBTS1 and form a client-specific TBCL bit stream for the current group.

If the equipment EQ is an intermediate equipment or the server SV, the bit train TBCL thus formed is transmitted to the customer CL via the network R. If the equipment EQ is the final customer, it is transmitted to a decoder.

In the example shown, the intermediate equipment received the bitstreams in independent containers.

According to a second option, not shown, he received them multiplexed into a single container.

According to a third option, illustrated by FIG. 6A, the bitstreams are segmented by an intermediate equipment EQ 'which does not implement the tattooing method according to the invention. The equipment EQ 'receives the unsegmented bitstreams, extracts them from their container, segments them, encapsulates them again and transmits them in the network to one or more clients. They will then be tattooed by another equipment, intermediary or client. One advantage is that non-segmented bitstreams can be broadcast in multicast mode, for example to segmentation equipment.

According to a fourth option illustrated in FIG. 6B and combinable with one of the two preceding ones, it has received the unsegmented flows and implements temporal segmentation at its level. Typically, according to the DASH standard, the time segments used have a size of 1 second, which means that there will be approximately 2 segments per group of images, for a group of 50 images. In this case, it is understood that the end customer will request the segments directly from this intermediate equipment EQ ".

This last mode of transport, illustrated by FIGS. 6A and 6B, corresponds to the "mezzanine" mode specified by the MPEG-2 TS standard. According to this mode the initial bitstreams are prepared at the level of the initial encoding by the server equipment to allow a subsequent "aligned" segmentation for all the binary trains transported, regardless of the quality of the associated encoding. In other words, the segmentation performs a division at the boundaries between images of different types, for example Intra, Inter type P or Inter type B for example. This is particularly suitable for adaptive transmission, in which a client can request segments of different quality to adapt to variations in the transmission conditions in the telecommunication network.

Referring to Figure 7, the steps of the method of processing an image sequence according to a second embodiment of the invention are now described.

The steps E0 for partitioning, El for forming a main group, E2 for forming a secondary group are unchanged.

It will be noted, however, that during step E1, the option already mentioned with reference to FIG. 3 is advantageously chosen, which consists in assigning values of predetermined and invariable intensities in the tattoo zone ZT of the images of the main group.

Indeed, according to this second embodiment of the invention, ab initio tattooing information is not inserted in the main group. The tattooing zone (s) determined during partitioning of the current group are provided in the main group to subsequently receive the tattoo information value for one or more clients.

During a step E3, the main group is encode in a conventional manner, in order to obtain a binary bit TBP '. An advantage of filling the tattoo zone (s) with values of predetermined and invariable intensities on the group is to optimize the computation resources, since the coding is simplified, the storage resources, with a size of train smaller binary and transmission resources.

For a tattooing area ZT of the N images of the current group, E4 and E7 are formed at least two secondary groups SS1 and SS1 comprising N "thumbnails" of dimensions equal to that of the zone ZT, in a manner similar to that described in relation to 3. Advantageously, the "images" of SS1 and SS2 are assigned the intensity values of the elements of the tattooing area ZT in the current group. It is understood that at this stage, the secondary groups SS1 and SS2 are identical. During the steps E5 and E8, the subtypes IT1 and IT2 are respectively inserted in the secondary groups SS1 and SS2, in a manner similar to that described for the first embodiment of the invention in connection with FIG. 2.

It is assumed that IT1 and IT2 are the two possible values of tattoo information, 0 and 1 in binary. If this tattoo information is of n-ary type with n> 2, n secondary groups will be formed to insert each of the possible values of the tattoo information into a separate secondary group.

During steps E6 and E9, the secondary groups GS1 and GS2 are respectively encoded in a manner similar to that described for the first embodiment of the invention. First and second secondary bit streams TBST1 'and TBST2' are obtained.

Advantageously, the bitstreams obtained TBP ', TBST1' and TBST2 'are stored in a memory M. For example, it is a memory of a server equipment implementing the invention.

In E10, the bit trains obtained are encapsulated in a container, for example as specified in the TS or ISOBMFF standards already mentioned, and they are transmitted via a telecommunications network R.

Steps E0 to E10 are then repeated for subsequent groups of the image sequence.

With regard to the EO partitioning step, it is possible, for simplicity, to decide to apply the same partitioning and the same choice of positioning of the tattooing zone (s) to all the groups of the image sequence. According to a variant, illustrated by FIGS. 8A and 8B, the same partitioning of the images is reproduced on the current group SC, but the positioning of the tattooing zone ZT is changed. For example, one chooses to position the tattoo area in a spatial area including relevant semantic content. In Figure 8A corresponding to the current segment SG, the tattoo area ZT is positioned on a player. In Figure 8B corresponding to the next segment SG ₊ i, the tattoo area ZT has been moved to follow the player. It is understood that in this case, the method implements a preliminary step of analyzing the semantic content of the images of the current segment, for example tracking an object in the image sequence. For example, this analysis is based on a technique known to those skilled in the art and for example described in the document by Wren et al, entitled "Pfinder: real-time tracking of the human body", published in the journal IEEE Transactions on Pattern Analysis and Machine Intelligence, Volume: 19, Issue: 7, pp. 780 - 785 ISSN: 0162-8828, in July 1997. This technique consists in using a two-dimensional contour model and a color histogram model, associated with a MAP type indicator (for "Maximum A Posteriori"). , in English) to identify in particular the head, hands and feet of a subject. This variant is particularly advantageous in the second embodiment of the invention which has just been described, when it has been decided to replace the intensity values of the elements of the tattooing zone in the main group by predetermined values. . Indeed, if a user illegally captures the main bitstream, the decoded sequence he will obtain will not restore all the relevant content and will offer him a highly degraded experience.

In connection with Figure 10A, there is shown a server SV implementing the second embodiment of the invention. A current group GC of an image sequence Im is partitioned into spatial zones comprising at least one tattooing zone. A main group and a secondary group are formed. No tattoo information is inserted in the main group. A first tattoo information T1 = 1 is inserted into the first subgroup and a second tattooing information T2 = 0 is inserted into the second subgroup.

All three groups are encoded. The main group is zone-encoded so that data from areas other than the tattoo area do not depend on the tattoo area. A TBP main bit stream is obtained. Secondary groups are encoded conventionally. Secondary bit streams TBST1 'and TBST2' are obtained.

The TBP ', TBST1' and TBST2 'bitstreams are encapsulated in one, two or three containers which are transmitted to one or more clients via the transmission network R.

The operations are repeated for the next groups in the image sequence. According to the second embodiment of the invention, at least three bitstreams are thus transmitted in the telecommunications network, intended for one or more clients: a main bit stream TBP 'comprising coded data representative of groups of images of the sequence of images to be delivered to one or more clients. At least one tattooing zone has been determined in which the intensity values of the elements of the images of the current segment have advantageously been replaced by predetermined values that are more economical to code. Zone coding has been applied to the group so that the coded data representative of the tattooing area of the group images and those representative of the remainder of the images are independent of one another;

at least a first secondary bit stream TBST1 'comprising coded data representative of a secondary group comprising thumbnails of dimensions equal to those of the tattooing zone and, for each image, intensity information of the tattooing zone in the group of original images. In the "thumbnails" of this secondary group IT1 tattooing information has been inserted. The "thumbnails" of the secondary group were encoded, using an encoding scheme compatible with that used for the main group; and

at least one second secondary bit stream TBST2 'comprising coded data representative of a secondary group comprising thumbnails of dimensions equal to those of the tattooing zone and, for each image, information of intensity of the tattooing zone in the group of original images. In the thumbnails of this group has been added IT2 tattoo information distinct from IT1. The thumbnails of the second subgroup were encoded, using a coding scheme compatible with that used for the main group; If the tattoo information is n-ary with n> 2, then n secondary bit streams are transmitted.

According to one variant, several tattooing zones are defined in the images of a group or the n possible values are transmitted over n successive segments.

Referring to Figure 9, the steps of a method of tattooing a digital image sequence according to the second embodiment of the invention are now described.

It is assumed that the bit streams TBP ', TBST1' and TBST2 'are transmitted to a client equipment via a telecommunications network. The tattooing method which will now be described may be implemented by the client equipment or by a network equipment, for example a server or a router placed at a break in the path of the bit trains. A current image group GC of the digital image sequence to be tattooed is considered for delivery to a client. This client is identified by a tattoo identifier comprising a sequence of B tattoo information, with B non-zero integer.

The step T 1 'of obtaining the tattoo information value (s), for example a binary value, to be inserted in the current segment, for the customer, is identical to that already described in relation to FIG. 4. For example, this ITCL information is equal to IT1 for the tattoo area ZT.

For example, it is assumed that it is the i ^th bit of the IDTCL tattoo identifier of the client which comprises B, a non-zero integer number for example equal to 20 (which corresponds to more than one million possible identifiers). In T2 ', at least the main bit stream TBP' corresponding to the current group GC is received.

If the TBP master bitstream has previously been multiplexed to one or more secondary bitstreams before being encapsulated in a transport container, all bitstreams, primary and secondary, are necessarily received during this step. In Τ3 ', information is obtained relating to a tattoo information value inserted into the tattooing area ZT of the main group corresponding to the main bit stream TBP received. For example, if the watermarking information is binary, we get 0 if bit 0 was inserted in the current group, 1 if bit 1 was inserted in the current segment and 2 if no bit was inserted into the current segment. current group. For example, this information is reported in the container that encapsulates the TBP main bit stream.

In this second embodiment of the invention, the main bit stream TBP 'does not contain tattoo information. The information obtained is 2 in the binary case. It is therefore appropriate to receive at least one secondary binary train. At T4 ', information relating to the tattoo information values inserted in the secondary bit streams TBTS1' and TBTS2 'associated with the received TBP main bit stream is obtained. For example, the equipment that implements the tattooing process has previously obtained the information that the main bit stream carries the value IT1 and that the secondary bit stream carries the value IT2. As a variant, this information is indicated in the header of the container of the main bitstream TBP '.

If the tattoo information is binary, 0 is obtained if bit 0 has been inserted in the current segment, 1 if bit 1 has been inserted in the current segment and 2 if no bit has been inserted in the current group.

At T5 ', it is determined which secondary bit stream contains the tattoo information value to be inserted for the customer into the tattoo area ZT. In the remainder of the description, it is assumed that it is ITCL = IT1.

At T6 ', the secondary bit stream TBST1' containing the desired tattoo information is received.

If, on the contrary, it had been desired to insert the IT2 tattooing information, it would have implemented the step T7 'of receiving the second secondary bit stream TBST2'.

In T8 ', a new bit stream TBCL' is formed by replacing the coded data of the main bitstream TBP 'corresponding to the tattoo zone ZT with those of the secondary bitstream TBST1'. This produces for the current group a bit stream TBCL integrating the tattoo information value for the customer CL in the tattoo area ZT.

In connection with FIG. 20B, bit streams TBP ', TBST1' and TBST2 'are received by EQ equipment' which may be intermediate, or SV server or end customer. This equipment implements the tattooing method according to the second embodiment of the invention. It processes at least the TBP main bit stream it extracts from its CTR container and, depending on the ITCL tattoo information to be transmitted to the client CL, it decides the secondary bit stream TBST1 'or TBST2' to be processed.

In this example, it is considered that the ITCL tattoo information of the client is Tl. It is contained in the coded data of the first secondary bit stream TBSTl '. The intermediate equipment E 'obtained this information, for example by reading the header of the container of the TBP' main bitstream or of the secondary bitstream TBST1 ', for example a metadata field of the transport container.

A COMPO composition operation is therefore implemented to replace the coded data of the tattooing area ZT of the main bit stream with that of the secondary bit stream TBTS1 and to form a client-specific bit stream TBCL 'for the current segment SC.

If the equipment EQ is an intermediate equipment or the server SV, the binary train TBCL 'thus formed is encapsulated in a container and then transmitted to the customer CL via the network R. If the equipment EQ is the final customer, it is transmitted to a decoder. According to a variant, already described for the first embodiment of the invention, the intermediate equipment segments the bit stream TBCL 'formed for the customer before encapsulating it in the transport container.

It will be noted that the invention which has just been described can be implemented by means of software and / or hardware components. In this context, the terms "module" and "entity", used in this document, may correspond either to a software component, or to a hardware component, or to a set of hardware and / or software components, capable of implementing perform the function (s) described for the module or entity concerned.

In relation to FIG. 11A, an example of a simplified structure of a device 100 for processing a digital image sequence according to the invention is now presented. The device 100 implements the treatment method according to the invention which has just been described in relation with FIGS. 2 and 5.

For example, the device 100 comprises a processing unit 110, equipped with a processor μΐ, and driven by a computer program Pgl 120, stored in a memory 130 and implementing the method according to the invention. At initialization, the code instructions of the computer program Pgi 120 are for example loaded into a RAM before being executed by the processor of the processing unit 110. The processor of the processing unit 110 implements the steps of the method described above, according to the instructions of the computer program 120.

In this exemplary embodiment of the invention, the device 100 comprises at least the following units: partitioning part of the images of the current group GC into at least two areas co-located in the images of the group and comprising at least one tattooing area ZT ,

FORM GP forming a main group comprising the partitioned images of the current group,

- ENC TBP for obtaining a main bit train representative of a zone encoding of the main group formed, in which for an area other than said at least one tattooing zone, the pixels of this main zone are not predicted by reference to pixels of the tattoo area of an image of the group, and for a said tattoo area,

- FORM GS for forming a secondary group of the same temporal dimension as the main group and of spatial dimensions equal to those of the tattooing area; - INS IT1 for inserting a first IT1 tattoo information value into the secondary group formed,

- ENC TBST1 for obtaining a first representative sub-bit secondary train TBST1 of the encoded secondary group including the first tattoo information value and a transmission unit of the main bit stream and the at least one first secondary bit stream destined for at least one customer.

According to a first embodiment of the invention, the device 100 comprises an INS insertion unit T2 of a second tattoo information value IT2 in the tattooing area of the main group.

According to a second embodiment of the invention, the device 100 further comprises the following units:

FORM GS2 forming a second secondary group of the same temporal dimension as the main group and of spatial dimensions equal to those of the tattoo zone, INS IT2 inserting a second IT2 tattoo information value distinct from IT1 in the secondary group formed, a unit for obtaining a second representative secondary bit stream TBST2 of the encoded secondary group including the second value of tattoo information, and TX SEND of the main bitstream, the first secondary bitstream and the at least second secondary bitstream in the telecommunication network to at least one client. Advantageously, this transmission unit comprises a sub-unit for encapsulating the bit streams in one or more transport containers. The device 100 further comprises a storage unit Ml for storing the main and secondary bitstreams obtained.

These units are driven by the μΐ processor of the processing unit 110.

Advantageously, such a device 100 can be integrated with an SV server equipment. The device 100 is then arranged to cooperate at least with the following module of the server SV: a data transmission / reception module E / R, through which the bit streams are transmitted in a telecommunications network, for example a wired, wireless or radio network.

In relation to FIG. 11B, an example of a simplified structure of a tattooing device 200 of a digital image sequence according to the invention is now presented. The device 200 implements the tattooing method according to the invention which has just been described in relation with FIGS. 4 and 7.

For example, the device 200 comprises a processing unit 210, equipped with a processor μ2, and driven by a computer program Pg2 220, stored in a memory 230 and implementing the method according to the invention. At initialization, the code Pg ₂₂₂₀ computer program instructions are loaded for example in a RAM memory before being executed by the processor of the processing unit 210. The processor of the processing unit 210 implements the steps of the method described above, according to the instructions of the computer program 220.

In this embodiment of the invention, the device 200 comprises at least the following units:

- GET IDCL preliminary obtaining a representative value of at least one tattoo information, said customer tattoo information, to be inserted into the current group of images intended for auditing at least one client;

REC TBP receiving a main bit stream comprising coded data representative of a main group, formed from the original images of the current group partitioned into at least two predetermined spatial areas. Spatial areas are collocated in the group's images and include at least one so-called tattoo area. The coded data is obtained by means of a spatial zone encoding of the main group, wherein the prediction of the pixels of an area of an image of the segment other than the said at least one tattooing area is not made by reference to the pixels at least one tattooing area of said image or another image of the group;

- GET ITBP for obtaining information relating to a tattoo information value inserted into the current group of the received primary bitstream;

for a tattooing area, the device comprises the following units that can be implemented when the value obtained does not equal the tattooing information of the client:

■ REC TBSTi receiving at least a first secondary bit stream comprising coded data representative of a subgroup, wherein a tattoo information value equal to the tattoo information of the client has been previously inserted, said group being of the same temporal dimension as the current group and of spatial dimensions equal to those of the tattooing area;

■ COMP TBP + TBTSi composition of a bit stream for auditing at least one client, by replacing the coded data associated with said at least one tattooing area in the main group, by coded data of the secondary bitstream.

The device 200 further comprises a unit M2 for storing the compound bitstream.

These units are driven by the processor μ2 of the processing unit 210.

Advantageously, such a device 200 may be integrated with an EQ equipment located at a cutoff of the path followed by the bitstreams to the client. This is for example the SV server, an intermediate equipment type router or server or a client terminal. The device 200 is then arranged to cooperate at least with the following module of the equipment EQ: a data transmission / reception module E / R, through which the bitstreams are received from a telecommunications network, for example a wired wireless network or radio, by the equipment EQ.

It goes without saying that the embodiments which have been described above have been given for purely indicative and non-limiting purposes, and that many modifications can easily be made by those skilled in the art without departing from the scope. of the invention.

Claims

A method of processing a sequence of digital images for transmission to at least one client via a telecommunications network, said sequence being divided into a plurality of groups of images, said method being characterized in that, the images of a group being partitioned in spatial zones, it comprises the following steps, implemented for a group of images, said current group:

a) forming (E1) a main group comprising the original images of the current group, said images being partitioned into at least two predetermined spatial areas, located at the same spatial coordinates, or collocated, in the images of the current group and comprising at least one tattooing zone;

b) obtaining (E3) a main bitstream representative of a zone encoding of the images of the main group formed, in which for an area other than said at least one tattooing zone, the pixels of this zone are not predicted by reference to pixels in the tattoo area of an image of the group;

- c) for a said tattoo area:

o formation (E4) of a secondary group of images of the same temporal dimension as the main group and of spatial dimensions equal to those of the tattooing area;

o inserting (E5) a first tattoo information value into the formed secondary group;

obtaining (E6) a first secondary bit stream representative of the images of the encoded secondary group including the first tattoo information value; d) transmitting (E10) the main bitstream, and the at least one first secondary bitstream in the telecommunication network to at least one client.

A method of processing a sequence of digital images for transmission to at least one customer via a telecommunications network according to claim 1, characterized in that it comprises an insertion step (E2) of a second Tattoo information, distinct from the first, in the tattoo area of the main group formed.

A method of processing a sequence of digital images for transmission to at least one customer via a telecommunications network according to claim 1, characterized in that it further comprises the following steps:

for a tattoo area: o formation (E7) of a second group of secondary images of the same temporal dimension as the main group and of spatial dimensions equal to those of the tattooing area;

o insertion (E8) in the second secondary group formed by at least a second tattoo information value;

obtaining (E9) at least one second secondary bit stream comprising coded data representative of the secondary group including the second value of tattooing information;

o transmission (E10) of the at least one second secondary bitstream to at least one client.

A method of processing a digital image sequence according to claim 3, characterized in that the step of forming the main group comprises replacing the original intensities of the at least one tattooing area with intensity values predetermined.

A method of processing a digital image sequence according to claim 4, characterized in that the predetermined values are invariable values.

A method of processing a digital image sequence according to one of the preceding claims, characterized in that the step of forming a secondary group for a tattooing area comprises extracting the intensity values of the pixels of the tattoo area in the original images of the current group.

A method of processing a digital image sequence according to one of the preceding claims, characterized in that the method comprises a step of choosing said at least one tattooing zone among the partitioned zones.

A method of processing a sequence of digital images according to one of the preceding claims, characterized in that it further comprises a step of determining an enlarged tattoo area in the main group images, including the area of tattoo and a border of predetermined width around said zone, the zone encoding comprises a step of applying a deblocking filter of size less than or equal to the predetermined width at the borders of the zones of the images of the main group and for a an area of an image other than said at least one tattooing area, the prediction of the pixels of the area does not refer to the pixels of said at least one enlarged tattooing area of another image of the group.

Method for processing a digital image sequence according to one of the preceding claims, characterized in that the partitioning implemented in the training step of the main group comprises at least first and second tattooing areas and the step of inserting at least one first tattooing information into the secondary group includes inserting a first tattooing information into the first area and a third tattoo information in the second zone.

A device (100) for processing a sequence of digital images for transmission to at least one client via a telecommunications network, said sequence being divided into a plurality of groups of images, said device being characterized by that, the images of a group being partitioned into spatial zones, it comprises the following units, which can be implemented for a group of images, called the current group:

- a) formation (FORM GP) of a main group comprising the original images of the current group partitioned in at least two predetermined spatial areas, located at the same spatial coordinates, or collocated, in the images of the current group and comprising at least less a so-called tattoo area;

b) obtaining (ENC TBP) a main bit train representative of a zone encoding of the images of the main group formed, in which for an area other than said at least one tattooing zone, the pixels of this zone are not predicted by reference to pixels in the tattoo area of an image of the group;

- c) for a said tattoo area:

o formation (FORM GS1 / GS2) of at least one secondary group of images of the same temporal dimension as the main group and of spatial dimensions equal to those of the tattooing area;

o insertion (INS IT1 / IT2) of a first tattoo information value in the formed secondary group;

obtaining (ENC TBST1 / TBST2) a first secondary bitstream representative of the images of the encoded secondary group including the first tattoo information value;

d) transmitting (SEND) the main bitstream, and the at least one first secondary bitstream in the telecommunication network to at least one client.

11. Server equipment (SV, 10) capable of transmitting one or more bitstreams comprising coded data representative of a video sequence to at least one client equipment (20), characterized in that it comprises a processing device according to the claim 10.

12. Method of tattooing a sequence of digital images transmitted in a telecommunication network to at least one client, said sequence being divided into groups image, characterized in that said method comprises the following steps, implemented for one group, said current group:

- Obtaining (Tl, Tl ') prior to a representative value of at least one tattoo information, said customer tattoo information, to be inserted into the current group for auditing at least one customer;

receiving (T2, T2 ') a main bitstream comprising coded data representative of a main group, formed from the original images of the current group partitioned into at least two predetermined spatial areas, located at the same spatial coordinates, or collocated, in the images of the group, and comprising at least one so-called tattooing zone, the coded data having been obtained using a coding by spatial zone of the main group, according to which the prediction of the pixels of a zone an image of the group other than said at least one tattooing area is not made by reference to the pixels of said at least one tattooing area of said image or another image of the group;

obtaining (T3, T3 ') information relating to a tattoo information value inserted in the current group of the received primary bitstream;

o for a said tattoo area:

Receiving (T5, Τ6 ', Τ7') at least a first secondary bit stream comprising coded data representative of a secondary image group, wherein a tattoo information value equal to the tattoo information the client has previously been inserted, said secondary group being of the same temporal dimension as the current group and of spatial dimensions equal to those of the tattooing zone;

■ composition (T6, T8 ') of a bit stream intended for the said at least one client, by replacing the coded data associated with the said at least one tattooing area in the main group with the coded data of the secondary bitstream.

Device (200) for tattooing a sequence of digital images transmitted in a telecommunication network to at least one client, said sequence being divided into groups of images, characterized in that said device comprises the following units, Suitable for being implemented for a group, said group:

- Getting (GET ITCL) prior to a representative value of at least one tattoo information, said customer tattoo information, to be inserted into the current group for auditing at least one customer; reception (REC TBP) of a main bit stream comprising coded data representative of a main group, formed from the original group images partitioned in at least two predetermined spatial areas, located at the same spatial coordinates, or collocated , in the images of the group, and comprising at least one so-called tattooing area, the coded data having been obtained using a coding by spatial zone of the main group, according to which the prediction of the pixels of a zone of an image of the group other than said at least one tattooing area is not made by reference to the pixels of said at least one tattooing area of said image or another image of the group;

obtaining (GET ITBP) information relating to a tattoo information value inserted into the current group of the received primary bitstream;

o for a said tattoo area:

Receiving (REC TBSTi) at least one first secondary bit stream comprising encoded data representative of a subgroup of images, wherein a tattoo information value equal to the tattoo information of the client has previously been inserted, said secondary group being of the same temporal dimension as the current group and of spatial dimensions equal to those of the tattooing zone;

• composition (COMP) of a binary train intended for auditing at least one client, by replacing the coded data associated with said at least one tattooing area in the main group, with the coded data of the secondary bitstream. 14. Communication equipment (20, EQ, EQ ', EQ') adapted to receive one or more bitstreams comprising coded data representative of a sequence of images from a server equipment and to transmit them to one or several receiving client equipment, characterized in that it comprises a tattooing device according to claim 13.

15. Customer equipment (20) capable of receiving one or more bitstreams comprising encoded data representative of a sequence of images from a server equipment, comprising a decoder adapted to decode the received bit streams, characterized in that it further comprises a tattooing device according to claim 13.

16. Signal carrying encoded data representative of a sequence of digital images for transmission to at least one customer via a telecommunications network, said sequence being divided into groups of images, characterized in that, for said group, said current group, said coded data comprises: a main bit stream (TBP, TBP ') comprises coded data representative of a main group formed by partitioning the original images of the current group in at least two predetermined spatial zones, located at the same spatial coordinates, or collocated, in the images of the main group, and comprising at least one so-called tattooing zone, said zones having been obtained by zone encoding images of the main group, wherein for an area other than said at least one tattooing area, the pixels of the area are not predicted by reference to pixels in the tattooing area of an image of the main group;

for said at least one tattoo area:

at least one first secondary bit stream (TBST1, TBST2) comprising coded data representative of images of a secondary group, of the same temporal dimension as the main group and of spatial dimensions equal to those of the tattooing zone, in which a first representative value of a tattoo information has been inserted;

said bitstreams being intended to be received by communication equipment capable of determining at least one tattoo information value to be associated with at least one client, and, when the customer's tattoo information value is equal to the first tattooing information, to redial, from the received bitstreams, a bit stream intended for said at least one client, by replacing the coded data of the main bitstream associated with said at least one tattooing area in the main group, by the data encoded bits of the secondary bitstream.

Signal according to claim 16, characterized in that, for said at least one tattooing area, a second tattoo information value (IT2) having been inserted into the tattooing area of the main group, the main bit stream (ΤΒΡ ' ) includes coded data representative of the main group and the second tattoo information value.

Computer program (Pgl) comprising instructions for implementing the processing method according to one of claims 1 to 9, when executed by a processor.

A computer program (Pg2) comprising instructions for carrying out the tattooing method according to claim 12 when executed by a processor.