Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
  • H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
  • H04N19/102—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the element, parameter or selection affected or controlled by the adaptive coding
  • H04N19/119—Adaptive subdivision aspects, e.g. subdivision of a picture into rectangular or non-rectangular coding blocks
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
  • H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
  • H04N19/134—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the element, parameter or criterion affecting or controlling the adaptive coding
  • H04N19/136—Incoming video signal characteristics or properties
  • H04N19/137—Motion inside a coding unit, e.g. average field, frame or block difference
  • H04N19/139—Analysis of motion vectors, e.g. their magnitude, direction, variance or reliability
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
  • H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
  • H04N19/134—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the element, parameter or criterion affecting or controlling the adaptive coding
  • H04N19/146—Data rate or code amount at the encoder output
  • H04N19/147—Data rate or code amount at the encoder output according to rate distortion criteria
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
  • H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
  • H04N19/169—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the adaptive coding
  • H04N19/17—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the adaptive coding the unit being an image region, e.g. an object
  • H04N19/176—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the adaptive coding the unit being an image region, e.g. an object the region being a block, e.g. a macroblock
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
  • H04N19/70—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals characterised by syntax aspects related to video coding, e.g. related to compression standards

Definitions

• the field of the invention is that of signal compression, in particular a digital image or a sequence of digital images, divided into blocks of pixels.
• the encoding / decoding of digital images applies in particular to images from at least one video sequence comprising:
• the present invention applies similarly to the coding / decoding of 2D or 3D type images.
• the invention may especially, but not exclusively, apply to video coding implemented in current AVC and HEVC video encoders and their extensions (MVC, 3D-AVC, MV-HEVC, 3D-HEVC, etc.), and to corresponding decoding.
• the invention can also be applied to audio coding, for example implemented in current audio encoders (EVS, OPUS, MPEG-H, etc.) and their extensions and the corresponding decoding.
• EVS audio encoders
• OPUS OPUS
• MPEG-H MPEG-H
• decoding for example implemented in current audio encoders (EVS, OPUS, MPEG-H, etc.) and their extensions and the corresponding decoding.
• a current block to be coded which constitutes an initial coding unit, is generally divided into a variable number of sub-blocks according to a predetermined cutting mode.
• Standard encoders offer regular partitioning, based on square or rectangular blocks of fixed size. Partitioning is always done from the initial, unpartitioned coding unit, and the final partitioning is calculated and reported from this neutral base.
• block partitioning of size 16x16, 8x8 or 4x4 authorized by the standard.
• FIG. 1b an exemplary partitioning enabled by the HEVC standard is illustrated.
• Patent application published under the number WO2011 / 127966 discloses a method of coding a 3D digital image, by planes, according to which the partitioning implemented for the coding of a plane of this image, for example the texture plane is inherited when coding the associated depth plane. This results in a substantial saving in terms of signage.
• the invention improves the situation.
• the invention particularly aims to overcome these disadvantages of the prior art.
• an object of the invention is to propose a solution that makes it possible to more efficiently predict and code complex image structures.
• Another objective of the invention is to propose a solution that is more efficient in compression.
• a coding method of a digital image said image (Im) being divided into a plurality of blocks of pixels processed in a sequence defined, characterized in that said method comprises the following steps, implemented for a current block (b): a) Obtaining a motion vector, called base motion vector of the current block with respect to a previously decoded reference image ;
• the invention is based on a completely new and inventive approach to image coding, which consists in applying to the current block the partitioning of the zone of the same size of the reference image pointed by the vector base movement obtained. for the current block.
• the invention takes advantage of the similarities of texture that exist between the current block of the current image and the area pointed in the image of the image. reference, to optimize the partitioning of the current block.
• the initial partitioning structure of the current block does not need to be transmitted to the decoder as signaling information in the data stream, since it can be obtained from the reference image. previously treated.
• partitioning structure is irregular: unlike standard encoders that apply a regular partitioning, for example of "quadtree" type, the partitioning proposed by the invention is not regular and, although complex, it remains simple to report because it is partly inherited from the reference image.
• the invention therefore makes it possible to better adapt the partitioning of a block to the content to be coded, while optimizing the coding cost.
• the invention thus proposes a new coding mode of a current block, which can advantageously be put into competition with other known coding modes of currently standardized coding schemes, such as, for example, the Intra, Inter or Merge modes. of the HEVC standard.
• the partitioning obtained from the reference image constitutes an initial partitioning of the current block, which the invention proposes to modify to adapt more finely to the specific texture of the current block.
• This modification can consist of a merge of neighboring partitions or a partition of a partition.
• this modification is validated by comparison with the initial partitioning. Once validated, the modification is signaled in the bit stream for example by difference with the initial partitioning. Reporting partitioning changes allows for low coding overhead.
• the step of obtaining the base motion vector comprises a motion estimation of the current block relative to the previously decoded reference image according to an error minimization criterion.
• the invention implements a particular motion estimation of the current block with respect to a reference image. It provides the basic motion vector used to obtain the initial partitioning of the current block from the reference image. It favors an error minimization criterion, rather than a coding cost criterion of the block, so as to guarantee that the content of the area pointed by the estimated basic motion vector is as similar as possible to that of the current block. .
• the modification comprises a merger of a sub-block of the coded current partitioning with at least one neighboring sub-block already coded.
• a modification proposed by the invention is to merge two or more neighboring sub-blocks of the current block to encode them as a single partition.
• the modification of the partitioning is indicated in the bit stream. Because of the legacy of initial partitioning, signaling is not a significant additional cost, especially since a basic motion vector can be saved as a result of this merger.
• the invention makes it possible to make a compromise between the additional cost related to the modification of the partitioning, and the reduction of the cost associated with the signaling of the motion vector
• the modification of the current partitioning further comprises a division of at least one sub-block into at least two sub-blocks.
• the step of cutting said at least one sub-block into at least two sub-blocks comprises the implementation of steps a) and b) of obtaining a basic motion vector and applying partitioning of the area pointed by the base motion vector for the at least one current sub-block.
• the principle of defining an initial partitioning of the current block from that of the block pointed by the motion vector estimated in the reference image is here applied recursively for the cut sub-blocks.
• Such a coding device of a digital image is particular in that it is able to implement the following units, implemented for a current block:
• said coding comprising a modification of the partitioning of the current block into sub-blocks according to predetermined rules, an encoding of the modified partitioning sub-blocks including the coding of the partitioning modification signaling information and a modified partitioning validation by applying a rate-distortion criterion to the coded sub-blocks of the modified partitioning.
• the invention also relates to a method for decoding a digital image from a bit stream comprising coded data representative of said image, said image being divided into a plurality of blocks processed in a defined order, said method comprising the following steps, implemented for a block, called current block: a ') Obtaining a basic motion vector between the current block and a previously decoded reference image, said motion vector pointing to an area of the image of reference, of the same size as that of the current block; b ') Obtaining a sub-block partitioning of the area pointed in the reference image by the base motion vector and application of the partitioning obtained to the current block; c ') Course of the sub-blocks of the current block according to a predetermined order of travel and decoding of the coded data read in the bitstream for the sub-blocks traveled, said decoding comprising a modification of the initial partitioning, obtained for the current block according to coded data representative of a signaling of the partitioning modification and the decoding of the modified partitioning
• the decoder method reproduces the principle of application to the current partitioning block of a zone of the same size pointed by the motion vector of the current block in a reference image proposed by the invention.
• this coding mode of the invention for the current block is reported in the bit stream, which further comprises a representative field of the base motion vector to use.
• This basic movement vector may have been estimated specifically to code the current block according to the invention and in this case, the field in question codes its components.
• it corresponds to an estimated motion vector for a neighboring block and the field comprises an index representative of the neighboring block.
• the initial partitioning is advantageously modified according to the signaling data read in the bit stream.
• the step of modifying the initial partitioning replaces the at least two neighboring sub-blocks of the initial partitioning with a sub-block in the modified partitioning and the step decoding includes decoding the sub-block.
• the signaling of this merge in the bit stream allows the decoder to update the initial partitioning.
• the step of modifying the partitioning applies the signaling division to the current sub-block and the decoding step decodes the sub-blocks obtained in a predetermined order of travel.
• the signaling of the division into the bitstream allows the decoder to update the initial partitioning.
• the signalised cutting is a regular cutting, for example of the "quadtree" type.
• the signaling data indicates to the decoder that the coding mode chosen for the current sub-block is the coding mode according to the invention, that is to say by applying the partitioning of a zone of the reference image pointed to by a basic motion vector.
• the decoder then again implements steps a '), b') and c ') for the current sub-block, which leads to an irregular division of this sub-block.
• the decoding method that has just been described is advantageously implemented by a device for decoding a digital image according to such a device. decoding a digital image from a bit stream comprising encoded data representative of said image, said image being divided into a plurality of processed blocks in a defined order, is particular in that it comprises the following units, capable to be implemented for a block, called current block:
• the invention relates to a signal carrying a bit stream comprising coded data representative of a digital image, said digital image being divided into blocks of processed pixels in a defined order.
• the signal according to the invention is particular in that, for a current block, said coded data comprise a field representative of a basic motion vector of the current block with respect to a reference image, a field representative of a coding mode. by applying the partitioning of the zone of the same size as the current block, pointed by the base motion vector in the reference image, said initial partitioning, and coded data representative of a signaling of the modification of the initial partitioning.
• the invention relates to a user terminal.
• a user terminal is particular in that it comprises a device for encoding a digital image and a device for decoding a digital image according to the invention.
• the invention also relates to a computer program comprising instructions for implementing the steps of a method of encoding a digital image 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 method of decoding a digital image 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 encoding device of a digital image and the decoding device of a digital image according to the invention, possibly removable, respectively memorizing a computer program implementing an encoding method and a computer program implementing a decoding method, as described above.
• FIGS. 1a and 1b, already described, illustrate examples of block partitioning respectively authorized and prohibited by the AVC standard
• FIGS. 2a and 2b already described, illustrate examples of block partitioning respectively authorized and prohibited by the HEVC standard
• FIGS. 3a, 3b, 3c and 3d already described, respectively illustrate an example of a block texture having a homogeneous zone and details zones and steps for partitioning the block according to the HEVC standard
• FIG. 4 schematically shows the steps of a coding method of a digital image according to the prior art
• FIG. 1a and 1b, already described illustrate examples of block partitioning respectively authorized and prohibited by the AVC standard
• FIGS. 2a and 2b already described, illustrate examples of block partitioning respectively authorized and prohibited by the HEVC standard
• FIGS. 3a, 3b, 3c and 3d already described, respectively illustrate an example of a block texture having a homogeneous zone and details zones and steps for partitioning the block according to the HEVC standard
• FIG. 4 schematically shows the steps
• FIG. 5 schematically shows the steps of a method of encoding a digital image according to a first embodiment of the invention
• FIG. 6 schematically shows the steps of a method of decoding a digital image according to a second embodiment of the invention
• FIG. 7 details a first example of modification of the partitioning of the current block by cutting a sub-block of the partitioning of the current block
• FIG. 8 details a second example of coding of a current block implementing a modification of the partitioning of the block by cutting a sub-block of the partitioning of the current block
• FIG. 9 details a third exemplary coding of a current block implementing a modification of the block partitioning by merging a sub-block with a neighboring sub-block of the partitioning
• FIGS. 11a to 11c show an example of coding of a current block according to one embodiment of the invention, when several successive operations of melting and partitioning partitioning are implemented;
• Figure 12 schematically shows the steps of a method of decoding a digital image from encoded data according to an embodiment of the invention;
• Figure 13 schematically shows an example of a hardware structure of a coding device according to one embodiment of the invention;
• FIG. 14 schematically shows an example of a hardware structure of a decoding device according to one embodiment of the invention.
• the images are encoded by an encoder, the encoded data is inserted a bit stream TB transmitted to a decoder via a communication network, or a compressed file FC, intended to be stored on a hard disk for example.
• the decoder extracts the coded data, then received and decoded by a decoder in a predefined order known from the encoder and the decoder, for example in the temporal order II, then 12, and then IM, this order being able to differ according to the mode of the decoder. production.
• the current decoded picture ID will be noted. Note that, in a video encoder, the ID image is (re) constructed in the encoder so that it can be used to predict the other pixels of the video.
• each CU will undergo an encoding or decoding operation consisting of a sequence of operations, including non-exhaustively a prediction, a residue calculation, a transformation, a quantization and an entropy coding. This sequence of operations is presented in relation with Figure 4.
• the first block CTU to be processed is selected as current block b. For example, this is the first block (in lexicographic order). This block has NxN pixels.
• a prediction Pr of the original block b is determined.
• the prediction information related to P is encoded in the bit stream TB or compressed file FC.
• K possible prediction modes ml, ml, ..., mK with K nonzero integer.
• the prediction mode chosen for the current block b is the mk mode.
• Some prediction modes are associated with an Intra prediction, others with an INTER prediction, others with a MERGE prediction.
• the residue R is transformed into a transformed residue block, called RT, by a DCT transform or wavelet transform, both known to those skilled in the art and in particular implemented in the JPEG standards for the DCT and JPEG2000 for the wavelet transform.
• the transformed residue RT is quantized by conventional quantization means, for example scalar or vector, into a quantized residue block RQ.
• This quantized block RQ contains NxN coefficients. As known in the state of the art, these coefficients are scanned in a predetermined order so as to constitute a one-dimensional vector RQ [i], where the index i varies from 0 to N 2 -1. The index i is called the frequency of the coefficient RQ [i].
• these coefficients are scanned in increasing frequency order, for example along a zigzag path, which is known from the JPEG fixed image coding standard.
• the amplitude information of the coefficients of the residual block RQ is encoded by entropy coding, for example according to a Huffman coding or arithmetic coding technique.
• amplitude is meant here the absolute value of the coefficient.
• one or more information relating to the amplitude is encoded.
• CA amplitudes are obtained.
• the signs of the coefficients are simply encoded by a bit 0 or 1.
• the previous steps E1 to E5 are repeated for the possible partitions I of the current block b.
• each of the sub-blocks CU of the current block b are treated as previously described, a type of prediction (Inter or Intra) being authorized by CU.
• a type of prediction Inter or Intra
• the sub-blocks of a sub-block CU are all subjected to the same type of prediction.
• the coded data for each of the I possible partitionings are put into competition according to a rate-distortion criterion and the partitioning which obtains the best result according to this criterion is finally retained.
• a current block b of type CU of a following image, for example Ii with i integer greater than or equal to 2.
• a prediction mode of the Inter type according to which a block of Prediction Pr is obtained by motion compensation with respect to a previously coded and then decoded IR reference image.
• the current block b will be encoded according to a particular INTER prediction mode, specific to the invention.
• this mode may be in competition with other INTER or INTRA prediction modes known to those skilled in the art and specified by a coding standard such as HEVC or a future standard.
• a base motion vector MVb is determined which points to an area of the reference image, of the size of the current block b, also called prediction block Pr.
• this zone does not necessarily correspond to a block previously coded in the reference image IR, but that it may be straddling several blocks of this image.
• the prediction block Pr can be seen as a composition of adjacent pieces of the blocks of the reference image which it covers.
• the initial motion estimation phase only takes into account the pixel-to-pixel distortion, and in no case the concepts of coding cost, as is customary, for example in a diagram. encoding type HEVC.
• the objective of this motion estimation is to find the best prediction zone in the pixel-to-pixel distortion direction, in order to apply the partitioning of this zone to the current block.
• the coding cost is taken into account later in the competition between the different prediction modes, in particular that of the invention and those specified by a standard of the HEVC type, for example.
• partitioning of the prediction block Pr in the IR image is obtained.
• the partitions of the blocks of the reference image IR have been stored for this purpose in a memory and the partitioning of the prediction block Pr is reconstructed from the partitioning information stored for the blocks of the IR image at least partially covered by the prediction block Pr.
• the partitioning l P thus obtained does not necessarily satisfy the partitioning rules generally imposed by the specifications of a standard such as HEVC. In particular, it is not necessarily regular.
• An example of irregular partitioning obtained by the invention is illustrated in Figure 10a.
• the IP partitioning obtained is then applied to the current block b.
• a step c) the sub-blocks resulting from the IP partitioning applied to the current block b are traversed in a predetermined order and processed as described above in relation to FIG. 4.
• a prediction Pr is obtained, a residue R is calculated from this prediction Pr, then the residue is transformed, quantized and finally encoded (RC).
• the initial motion vector MVb is transmitted in the bit stream.
• the partitioning applied to the current block does not have to be reported since it can be deduced from that of the prediction block of the reference image.
• the coded data obtained are put in competition with those resulting from a conventional coding scheme, for example according to the HEVC standard.
• a rate-distortion criterion is taken into account to compare the different coding modes.
• the coded data from the partitioning that won the competition is inserted into the TB bit stream or into an FC file.
• step c) of coding of the sub-blocks of the current block b according to the IP partitioning according to a second embodiment of the invention is now detailed.
• the sub-blocks SB of the current block b are traversed in cl, according to a predetermined order of travel.
• the sub-block is subjected in C3 to a modification of partitioning.
• This modification can be either a subdivision of the sub-block into sub-blocks of smaller sizes or a merger of the sub-block with a neighboring sub-block already processed.
• the new sub-block (s) obtained is then coded in c4.
• the modifications of the initial partitioning IPi applied to the current block b must be indicated in the bit stream TB since they can not be deduced from those of the prediction block of the reference image. .
• they are indicated by difference compared to the initial partitioning. It is understood that a possible signaling could be to indicate first the type of modification applied, division or merger, then the differences with the initial partitioning.
• c5 the coded data obtained in the first and second cases are put into competition and evaluated according to a distortion flow criterion. Partitioning is retained which achieves the best performance according to this criterion.
• the division of the current sub-block SB made into c'31 implements the principle of the invention, that is to say that it implements steps a), b) of the coding method according to the invention.
• a) an estimation of movement is carried out with respect to the reference image IR, a base motion vector MVb 'is obtained, in b) the partitioning of the prediction block pointed by the motion vector MVb' is obtained then applied to the SB current sub-block.
• signaling the division of a sub-block are possible: given a predetermined order of travel of the sub-blocks of the partitioning, one can cite as an example: signal for each sub-block of a partition a 0 or a 1 to indicate whether the current sub-block is cut for example in a "quadtree" mode and for each sub-block obtained, if it is redécoupé;
• the sub-block is redrawn, indicate the way in which the new partitioning is obtained, in accordance with the chosen cutting method. For example, if partitioning is split using a quadtree method as is the case under HEVC, the associated signaling follows the HEVC recommendation and in particular section 7.3.8.4 titled "Coding quadtree syntax".
• the sub-blocks of the current block are coded according to a predetermined order of travel.
• Step c32 merges the sub-block SB with a neighbor already coded SBV according to the order of travel.
• Figure 10b shows the enlarged sub-block SBf obtained.
• This enlarged sub-block SBf is coded in c42.
• the prediction of the merged sub-block SBf can be implemented according to a prediction mode of the Inter, Merge or Intra type, as previously described.
• a motion vector MVf is assigned to the enlarged sub-block, either by implementing a new motion estimation step that provides a new motion vector that will have to be transmitted to the decoder, or by reusing a motion vectors of one of the two merged sub-blocks.
• the reused movement vector can be signaled with an index in the bit stream.
• Twist of course or report only the number of the current sub-block, followed by the distance (in the order of travel) to the neighboring sub-block with which it merges (eg 0 for the first neighbor according to the order of travel).
• the RD cost of the fusion is calculated in c52.
• this calculation takes into account the cost of coding the residue of the enlarged sub-block, the cost of encoding its movement vector MVf and the cost of signaling the merger of the two neighboring sub-blocks.
• the calculated overall cost is compared in c52 to the sum of the costs of the two sub-blocks SB and SBV encoded separately and a decision to adopt the merger is taken in c62, if this overall cost is less than the sum of the coding costs of the separate sub-blocks. Otherwise, the merger is not retained.
• the encoder can test the merge of the current sub-block with another already coded neighbor sub-block.
• the bit stream TB produced by the coding method according to the invention is therefore particular in that it comprises, for the coding of a current block, relative signaling information:
• the encoding mode according to the invention namely the fact of applying the partitioning of the prediction block to the current block;
• a binary string may indicate that there has been a change in initial partitioning (1), or not (0).
• a binary sequence can indicate whether it is a division (0) or a merger (1).
• a binary sequence then describes the division and the merger.
• the division is indicated by a binary sequence in agreement with the selected cutting method. For example, if the partition is cut using a "quadtree" method like HEVC, the associated "quadtree” signaling follows the HEVC recommendation and in particular section 7.3.8.4 "Coding quadtree syntax".
• a merge is signaled by a binary sequence that describes whether the current block merges (1) or not (0) with its neighbor, according to a predefined order.
• the set of these binary sequences can be encoded using a Huffman type entropy coder, or arithmetic type with use of specific contexts in order to reduce the associated signaling cost;
• FIGS. 11a-11c an exemplary embodiment of the invention is presented according to which the initial partitioning of a current block b, is modified several times, some sub-blocks being merged, others being divided.
• FIG. 11a illustrates the fact that the partitioning corresponding to the prediction block is not necessarily regular, because it corresponds to pieces of partitioning of several blocks of the reference image.
• Figures 11b, 11c and 11d illustrate successive fusions.
• Figure 11c illustrates an example of sub-block splitting. Note that in this example, the number of motion vectors to be transmitted is 21 for a total number of 28 according to the HEVC standard. Of course, if too many mergers are implemented, the result is an increased signaling cost. It is therefore the coder who knows the coding cost of the modifications made to the initial partitioning and achieves the best compromise distortion rate.
• the bit stream TB produced by the coding method according to the invention is transmitted to a decoder.
• This decoder implements a decoding method according to the invention which will now be described in relation with FIG. 12.
• the decoder reads and analyzes in a known manner the coded DC data received in the bit stream.
• the coded data relating to a current block of a digital image Im are considered.
• the decoder retrieves at Tl signaling information relating to the partitioning mode MPA implemented to encode the current block b '. he this is for example a conventional partitioning, type "Quadtree" or the partitioning mode according to the invention.
• the decoder obtains in T2 the basic motion vector MVb 'to be used to determine the prediction block Pr' of the current block in the image reference IR '. According to the embodiment implemented, it can obtain either signaling information that indicates that the motion vector MVb 'is derived from that of a neighboring block already encoded or data representative of the motion vector itself. Once the motion vector MVb 'has been obtained, the decoder implements a step
• T3 obtaining an initial IPi partitioning of the current block.
• This partitioning is that of the prediction block Pr ', that is to say of the zone Zb' pointed by the motion vector MVb 'in the IR reference image already decoded.
• the decoder thus calculates the coordinates of this zone in the reference image and searches in memory for the partitioning of the different blocks of the reference image which contribute to this zone.
• this partitioning to the current block. This is his initial partitioning. It then begins in T5 to browse the sub-blocks defined by this initial partitioning according to a predetermined order of travel that it shares with the encoder. For example, this order of course is determined beforehand. For a current sub-block SB ', it extracts from the bit stream any signaling information relating to a modification of the initial partitioning of the block at this sub-block SB'. If it does not extract any information, the sub-block has not been modified. In this case, it decodes it from the coded data received in the bit stream. Alternatively, it extracts at T5 signaling information relating to a modification of the partitioning at the current sub-block.
• this information first comprises information representative of a type of modification applied to the initial partitioning, cutting or merging, followed by information representative of a difference between the modified partitioning and the initial partitioning.
• it is a division of the current sub-block.
• this division can be based on a classical partitioning of the "Quadtree" type or on the partitioning mode according to the invention.
• the decoder extracts from the bit stream the signaling information relating to this partitioning and the prediction mode used for each of the sub-blocks obtained. It classically decodes the sub-blocks obtained.
• the decoder repeats the steps already described, extraction of the bit stream signaling information relating to the motion vector (reused or encoded) and obtaining the motion vector, for obtaining the partitioning of the prediction sub-block of the reference image, for applying this partitioning to the current sub-block, and then for decoding the sub-blocks of the sub-block current recut.
• the modification made to the initial partitioning is a merger of the current sub-block with a neighboring sub-block already decoded.
• the decoder extracts from the bit stream signaling information for identifying the neighboring sub-block and updates the partitioning of the block b 'by replacing the merged sub-blocks with the enlarged sub-block. Note that there may be more than two neighboring merged sub-blocks in a single enlarged sub-block. It then reads in the bit stream the prediction mode implemented for the enlarged sub-block. In the case of an Inter prediction mode, it obtains the basic motion vector to be applied to the enlarged sub-block to compensate it in motion relative to the reference image.
• the decoding method reconstructs the quantized residue RQ' of the block b 'at T6 and dequantizes it. This last operation is carried out by means adapted to the quantization used during the coding, for example a scalar or vector dequantization ...) - Then it applies an inverse transformation of the dequantized current block and reconstructs the decoded block b 'by adding the residual to the prediction Pr 'of the current block b'.
• the reconstructed block b ' is integrated into the image being decoded.
• the terms "module” and "unit”, used in this document can correspond either to a software component, or to a hardware component, or to a set of hardware and / or software components, able to implement perform the function (s) described for the module or unit concerned.
• FIG. 13 an example of a simplified structure of a device 100 for encoding a digital image according to the invention is now presented.
• the device 100 implements the coding method according to the invention which has just been described in relation to FIGS. 4 to 9.
• the device 100 comprises a processing unit 110, equipped with a processor ⁇ ⁇ , and driven by a computer program Pg l 120, stored in a memory 130 and implementing the coding method according to the invention.
• the code instructions of the computer program Pgi 120 are for example loaded into a RAM memory before being executed by the processor of the processing unit 110.
• the processor of the processing unit 110 sets implement the steps of the method described above, according to the instructions of the computer program 120.
• the device 100 comprises at least one GET MVb unit for obtaining a basic motion vector for the current block with respect to a reference image, a GET PART unit for obtaining a partitioning of the PU prediction block pointed by the estimated base motion vector, a MAP PART unit for applying the partitioning obtained to the current block and a coding unit COD subblocks of the current block defined by the partitioning applied.
• the device 100 furthermore comprises an IP MOD unit for modifying the partitioning obtained for the block (b ') and a MOD validation unit VALID for the modification.
• Such a device 100 can be integrated with a user terminal TU.
• the device 100 is then arranged to cooperate with at least one data transmission / reception module E / R of the user terminal, via which the bit stream TB or the compressed file FC is transmitted in a telecommunications network. for example a wired network or a wireless network.
• FIG. 13 an example of a simplified structure of a device 200 for decoding a digital image according to the invention is now presented.
• the device 200 implements the decoding method according to the invention which has just been described in relation to FIG. 11.
• the device 200 comprises a processing unit 210, equipped with a processor ⁇ 2, and driven by a computer program Pg2 220, stored in a memory 230 and implementing the decoding method according to the invention.
• the code instructions of the computer program Pg2 220 are for example loaded into a RAM before being executed by the processor of the processing unit 210.
• the processor of the processing unit 210 sets implement the steps of the method described above, according to the instructions of the computer program 220.
• the device 200 comprises at least one GET unit MVb 'for obtaining a base motion vector MVb' between the current block and a previously decoded reference image, a GET PART unit d. obtaining a partitioning of the area pointed in the reference image (b '), a MAP PART unit applying the partitioning obtained to the current block (b) and a unit DEC of traversing the sub-blocks of the current block (b) according to a predetermined order of travel and decoding of the coded data read in the bitstream for the traversed sub-blocks.
• the device 200 further comprises an IP MOD unit for modifying the partitioning obtained for the block (b ') from coded data read in the bitstream TB.
• Such a device 200 can be integrated with a user terminal TU '.
• the device 200 is then arranged to cooperate at least with the following module of the terminal TU:
• a data transmission / reception module E / R through which the bit stream TB or the compressed file FC is received from a telecommunications network;
• An image rendering device DISP for example a terminal screen, through which the decoded digital image or the sequence of decoded images is returned to a user.
• a user terminal TU, TU ' can integrate both a coding device and a decoding device according to the invention.

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• 2014
  • 2014-12-22 FR FR1463137A patent/FR3030976B1/fr not_active Expired - Fee Related
• 2015
  • 2015-12-14 EP EP15823644.8A patent/EP3238449A1/de not_active Withdrawn
  • 2015-12-14 WO PCT/FR2015/053471 patent/WO2016102804A1/fr active Application Filing
  • 2015-12-14 US US15/538,970 patent/US20170353722A1/en not_active Abandoned

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