JP5937926B2 - Image encoding device, image decoding device, image encoding program, and image decoding program - Google Patents

Description

  The present invention relates to an image encoding device, an image decoding device, an image encoding program, and an image decoding program that perform inter-screen prediction of images.

  MPEG (Moving Picture Experts Group) -2, H.M. In a compression encoding method such as H.264 / AVC (Advanced Video Coding) or HEVC (High Efficiency Video Coding) under standardization, each frame of a video signal is divided into rectangular areas called blocks.

  In these compression coding systems, transform coding is used in which an image signal is converted into a frequency domain signal in units of blocks. The converted signal in the frequency domain is replaced with a representative value by quantization, and the degree of compression of video information is controlled by the degree of replacement of the representative value.

  Quantization is realized by dividing the input signal by a certain numerical value. The numerical value to be divided is controlled by the quantization parameter (Qp). The quantization parameter is changed and controlled in units of blocks, thereby determining the overall compression rate and image quality.

  MPEG-2 and H.264 In the H.264 / AVC standard, processing is performed in units of 16 × 16 pixel size blocks called macroblocks, and the quantization parameter can be converted for each macroblock.

  On the other hand, in the HEVC standard, a variable size block called a CU (Coding Unit) is introduced, and frequency conversion and quantization are performed in units of small TUs (Transformation Units) obtained by hierarchically dividing the CU. The quantization parameter in the HEVC standard is currently being studied with a mechanism for controlling in units of CUs.

  Since the value of the quantization parameter that changes in units of macroblocks or CUs is necessary information on the decoding side, it is encoded and transmitted to the decoding side. If the quantization parameter of each macroblock or each CU is encoded as it is, the amount of information becomes enormous. Therefore, a difference (delta Qp) from the coded macroblock or CU quantization parameter is calculated, and this difference value is calculated. Encoded.

  As a reference destination of difference calculation under consideration in the HEVC standard, there is a method of using a head block of a reference destination using a motion vector for a frame that is inter-screen encoded in addition to a neighboring CU in the same frame. (Non-Patent Document 1)

H.Aoki, K. Chono and Y. Senda, "CE4 Subtest 2: QP prediction based on intra / inter prediction (test 2.4.b)", JCT-VC document JCTVC-F103, Joint Collaborative Team on Video Coding (JCT- VC) of ITU-T SG16 WP3 and ISO / IEC JTC1 / SC29 / WG11 6th meeting, Torino, Italy, July 2011

  In the prior art, when using the reference frame of the motion vector of the processing target block, the position of the quantization parameter of the reference frame is fixed to the first block of the reference frame as the quantization parameter of the entire frame. The difference value of the quantization parameter from the upper left block is used.

  However, even if the quantization parameter between blocks at a predetermined fixed position is used, it is expected that there is motion between the frames. In the prior art, since this motion is not used for calculating the quantization parameter difference value of the entire frame, the two blocks to be used are not necessarily similar. Therefore, in the prior art, it cannot be said that the accuracy of the predicted value of the quantization parameter is high.

  Therefore, the present invention has been made in view of the above problems, and an object of the present invention is to provide an image encoding device, an image decoding device, and a program that can improve the accuracy of a prediction value of a quantization parameter.

  An image encoding apparatus according to an aspect of the present invention is an image encoding apparatus that performs frequency conversion for each block into which an image is divided and performs quantization using a quantization parameter, and performs processing in which inter-screen prediction is performed Considering the motion of the encoded block, the encoded block in the image including the target block and the similar block similar to the encoded block in the reference image referred to by the motion vector of the processing target block are considered. A value obtained by adding a difference value between the quantization parameter of the encoded block selected by the selection unit and the similar block to the quantization parameter of the selection unit selected by the selection unit and the block referred to by the motion vector of the processing target block Is a prediction unit that sets the prediction value of the quantization parameter of the processing target block.

  The selection unit may sequentially search for the encoded block, and when the motion vector of the encoded block refers to a block in the reference image, the block may be the similar block.

  The selection unit may use the similar block as an upper left block of the reference image, and select an encoded block at a position referred to by a backward vector of the motion vector from the upper left block.

  The selection unit may select an encoded block having the same motion vector as that of the processing target block and a similar block in the reference image referred to by the motion vector of the encoded block.

  An image decoding apparatus according to another aspect of the present invention is an image decoding apparatus that decodes a stream encoded by the image encoding apparatus, a decoding unit that performs entropy decoding on the stream, and a decoded quantization An inverse quantization unit that performs an inverse quantization process using the difference value of the parameter and the predicted value of the generated quantization parameter.

  In addition, the image coding program according to another aspect of the present invention performs inter-screen prediction on a computer in order to perform frequency conversion for each block into which an image is divided and perform quantization using a quantization parameter. Considering the motion of the coded block, the coded block in the image including the processing target block and the similar block similar to the coded block in the reference image referred to by the motion vector of the processing target block are considered. A value obtained by adding the difference value of the quantization parameter of the selected encoded block and the similar block to the quantization parameter of the block referred to by the motion vector of the processing target block; And a prediction step for setting a prediction value of the quantization parameter of the processing target block.

  Further, an image decoding program according to another aspect of the present invention includes a decoding step for entropy decoding the stream and a decoded quantization parameter for decoding a stream encoded by the image encoding device. And an inverse quantization step for performing an inverse quantization process using the generated difference value and the predicted value of the generated quantization parameter.

  According to the present invention, it is possible to improve the accuracy of the predicted value of the quantization parameter.

1 is a block diagram illustrating an example of a schematic configuration of an image encoding device according to Embodiment 1. FIG. FIG. 2 is a block diagram illustrating an example of a schematic configuration of a quantization unit and an entropy encoding unit according to the first embodiment. FIG. 3 is a block diagram illustrating an example of a schematic configuration of a quantization parameter prediction unit according to the first embodiment. The figure which shows the block selection example (the 1). The figure which shows the block selection example (the 2). The figure which shows the block selection example (the 3). 9 is a flowchart illustrating an example of a quantization parameter predicted value calculation process according to the first embodiment. FIG. 6 is a block diagram illustrating an example of a schematic configuration of an image decoding device according to a second embodiment. FIG. 9 is a block diagram illustrating an example of a schematic configuration of an image processing apparatus according to a third embodiment.

  Hereinafter, embodiments will be described in detail with reference to the accompanying drawings.

[Example 1]
<Configuration>
FIG. 1 is a block diagram illustrating an example of a schematic configuration of an image encoding device 10 according to the first embodiment. In the example illustrated in FIG. 1, the image encoding device 10 includes a preprocessing unit 100, a prediction error signal generation unit 101, an orthogonal transformation unit 102, a quantization unit 103, an entropy encoding unit 104, an inverse quantization unit 105, and an inverse orthogonal. A conversion unit 106, a decoded image generation unit 107, a deblocking filter unit 108, a loop filter unit 109, a decoded image storage unit 110, an intra prediction unit 111, an inter prediction unit 112, a motion vector calculation unit 113, and a prediction image selection unit 115 Have. An outline of each part will be described below.

  The preprocessing unit 100 rearranges the pictures in accordance with the picture type, and sequentially outputs the picture type and the frame image for each frame. The preprocessing unit 100 also performs block division for encoding and the like.

  The prediction error signal generation unit 101 acquires block data obtained by dividing an encoding target image of input moving image data into blocks (CU) such as 32 × 32, 16 × 16, and 8 × 8 pixels.

  The prediction error signal generation unit 101 generates a prediction error signal based on the block data and the block data of the prediction image output from the prediction image selection unit 115. The prediction error signal generation unit 101 outputs the generated prediction error signal to the orthogonal transformation unit 102.

  The orthogonal transform unit 102 performs orthogonal transform processing on the input prediction error signal in a transform unit (TU). The orthogonal transform unit 102 outputs a signal separated into horizontal and vertical frequency components by the orthogonal transform process to the quantization unit 103.

  The quantization unit 103 quantizes the output signal from the orthogonal transform unit 102. The quantization unit 103 reduces the code amount of the output signal by quantization, and outputs this output signal to the entropy encoding unit 104 and the inverse quantization unit 105.

  Further, the quantization unit 103 generates a predicted value of the quantization parameter using the quantization parameter in the decoded image. The process for generating the predicted value of the quantization parameter will be described later. The quantization unit 103 outputs the quantization parameter used for quantization to the entropy encoding unit 104.

  The entropy coding unit 104 entropy codes and outputs the output signal from the quantization unit 103, the motion vector information output from the motion vector calculation unit 113, the filter coefficient from the loop filter unit 109, and the like.

  The entropy encoding unit 104 encodes the quantization parameter. At this time, the entropy encoding unit 104 encodes the quantization parameter using the block in the reference image stored in the decoded image storage unit 110. The quantization parameter encoding process will be described later. Entropy coding is a method of assigning variable-length codes according to the appearance frequency of symbols.

  The inverse quantization unit 105 dequantizes the output signal from the quantization unit 103 and then outputs the output signal to the inverse orthogonal transform unit 106. The inverse orthogonal transform unit 106 performs an inverse orthogonal transform process on the output signal from the inverse quantization unit 105 and then outputs the output signal to the decoded image generation unit 107. By performing decoding processing by the inverse quantization unit 105 and the inverse orthogonal transform unit 106, a signal having the same level as the prediction error signal before encoding is obtained.

  The decoded image generation unit 107 adds the block data of the image subjected to motion compensation by the inter prediction unit 112 and the prediction error signal decoded by the inverse quantization unit 105 and the inverse orthogonal transform unit 106. The decoded image generation unit 107 outputs the decoded image block data generated by the addition to the deblocking filter unit 108.

  The deblocking filter unit 108 applies a filter for reducing block distortion to the decoded image output from the decoded image generation unit 107 and outputs the filtered image to the loop filter unit 109.

  The loop filter unit 109 is, for example, an ALF (Adaptive Loop Filter), and performs a filtering process using a decoded image subjected to the deblocking filtering process and an input image. For example, a Wiener filter is used for the filter processing, but other filters may be used.

  In addition, the loop filter unit 109 divides the input image into groups for each predetermined size, and generates an appropriate filter coefficient for each group. The loop filter unit 109 divides the decoded image subjected to the deblocking filter processing into groups for each predetermined size, and performs filter processing for each group using the generated filter coefficients. The loop filter unit 109 outputs the filter processing result to the decoded image storage unit 110 and accumulates it as a reference image. The predetermined size is, for example, an orthogonal transformation size.

  The decoded image storage unit 110 stores the input block data of the decoded image as new reference image data, and outputs the data to the intra prediction unit 111, the inter prediction unit 112, and the motion vector calculation unit 113.

  The intra prediction unit 111 generates block data of the predicted image from the already-encoded reference pixels for the processing target block of the encoding target image.

  The inter prediction unit 112 performs motion compensation on the reference image data acquired from the decoded image storage unit 110 with the motion vector provided from the motion vector calculation unit 113. Thereby, block data as a motion-compensated reference image is generated.

  The motion vector calculation unit 113 obtains a motion vector using the block data in the encoding target image and the reference image acquired from the decoded image storage unit 110. The motion vector is a value indicating a spatial deviation in units of blocks obtained using a block matching technique for searching for a position most similar to the processing target block from the reference image in units of blocks.

  The motion vector calculation unit 113 outputs the obtained motion vector to the inter prediction unit 112, and outputs motion vector information including information indicating the motion vector and the reference image to the entropy coding unit 104.

  The block data output from the intra prediction unit 111 and the inter prediction unit 112 are input to the predicted image selection unit 115.

  The predicted image selection unit 115 selects one of the block data acquired from the intra prediction unit 111 and the inter prediction unit 112 as a predicted image. The selected prediction image is output to the prediction error signal generation unit 101.

  The above-described configuration of the image encoding device 10 is merely an example, and the configuration may be changed depending on the mounting method. For example, a plurality of units may be configured together.

<Prediction of quantization parameter>
Next, the prediction of the quantization parameter in the first embodiment will be described. In the first embodiment, a prediction value of a quantization parameter is generated in consideration of a variation of a quantization parameter between a reference image of a motion vector of a processing target block and the processing target image.

"Constitution"
FIG. 2 is a block diagram illustrating an example of a schematic configuration of the quantization unit 103 and the entropy encoding unit 104 according to the first embodiment. Note that the entropy encoding unit 104 describes a configuration related to a quantization parameter, and does not describe other general configurations.

  In the example illustrated in FIG. 2, the quantization unit 103 includes a quantization control unit 201, a quantization parameter determination unit 203, and a quantization processing unit 205, and the entropy encoding unit 104 includes a quantization parameter prediction unit 207 and A parameter encoding unit 209 is included.

  The quantization control unit 201 sets quantization control information for the coefficient signal acquired from the orthogonal transform unit 102, for example, in coding units. The quantization control information is also called a quantization step. For example, the quantization control unit 201 sets the quantization control information of the encoding unit according to the bit rate and the desired image quality based on the coefficient signal of the conversion unit.

  The quantization control unit 201 sets, for example, quantization control information according to coefficient signal characteristics and the like after converting a preset information amount into an allocation amount to one CU. The setting of the quantization control information is not limited to this method.

  The quantization parameter determination unit 203 determines a quantization parameter for performing quantization control based on the quantization control information set by the quantization control unit 201. For example, the quantization parameter and the logarithm of the quantization step are in a proportional relationship.

  The quantization parameter determination unit 203 determines a quantization parameter from the quantization control information using this proportional relationship. The quantization parameter determination unit 203 outputs the determined quantization parameter to the quantization processing unit 205 and the quantization parameter prediction unit 207.

  The quantization processing unit 205 quantizes the coefficient signal using the quantization parameter acquired from the quantization parameter determination unit 203. For example, quantization is described in H.264. A known technique such as H.264 or HEVC may be used. The quantization processing unit 205 outputs the quantized coefficient signal to the entropy encoding unit 104 and the inverse quantization unit 105.

  When the quantization parameter prediction unit 207 acquires the quantization parameter from the quantization parameter determination unit 203, the quantization parameter prediction unit 207 specifies a processing target block of the acquired quantization parameter. The quantization parameter prediction unit 207 generates a prediction value of the quantization parameter for the processing target block using the quantization parameter of the encoded block. The generation of the predicted value will be described later with reference to FIG. The quantization parameter prediction unit 207 outputs the predicted prediction value to the parameter encoding unit 209.

  The parameter encoding unit 209 calculates a difference between the prediction value of the quantization parameter acquired from the quantization parameter prediction unit 207 and the quantization parameter of the processing target block, and encodes the difference value. The encoded difference value is included in the stream.

  FIG. 3 is a block diagram illustrating an example of a schematic configuration of the quantization parameter prediction unit 207 according to the first embodiment. The quantization parameter prediction unit 207 illustrated in FIG. 3 includes a block selection unit 301 and a prediction unit 303.

  The block selection unit 301 acquires the motion vector of the processing target block from the motion vector calculation unit 113, and specifies the block to which the motion vector refers. “A block referred to by a motion vector (also referred to as a reference block)” refers to a block in a reference image indicated by the motion vector.

  Further, the block selection unit 301 selects an encoded block in an image including a processing target block for which inter-screen prediction has been performed, and sets the encoded block in a reference image referred to by the motion vector of the processing target block. A similar block (also referred to as a similar block) is selected in consideration of the motion of the encoded block.

  Thereby, the influence by the difference of the quantization parameter between whole images can be made small by using the quantization parameter between similar blocks.

  The block selection unit 301 acquires block data in the reference image from the decoded image storage unit 110. The block selection unit 301 outputs, to the prediction unit 303, information indicating the block referred to by the motion vector of the processing target block, and the selected encoded block and a similar block in the reference image.

  The prediction unit 303 acquires block information from the block selection unit 301. The prediction unit 303 processes a value obtained by adding the difference value between the quantization parameter of the coded block and the similar block selected by the block selection unit 301 to the quantization parameter of the block referred to by the motion vector of the processing target block. The prediction value of the quantization parameter of the target block is set.

That is, the prediction unit 303 generates a prediction value of the quantization parameter using the following equation (1).
Predicted value = Qp_r + Qp_cf−Qp_rf Equation (1)
Qp_r: quantization parameter of the block referenced by the motion vector of the block to be processed Qp_cf: quantization parameter of the selected encoded block Qp_rf: quantization parameter of the selected similar block The prediction unit 303 quantizes each block The parameter is acquired from a buffer or the like that stores the quantization parameter of the block at which position of which image. The prediction unit 303 outputs the prediction value of the quantization parameter for the processing target block to the parameter encoding unit 209.

<Specific example>
Next, the block selected by the block selection unit 301 will be described using a specific example.

  FIG. 4 is a diagram illustrating a block selection example (part 1). In the example illustrated in FIG. 4, the block bk111 referred to by the motion vector of the processing target block bk101 in the processing target image fr101 is selected from the reference image fr110.

  The block selection unit 301 searches the encoded block in order from the upper left, and when the motion vector of the encoded block refers to a block in the reference image, this block is set as a similar block.

  In the example illustrated in FIG. 4, the block bk102 of the image fr101 represents a block that is first found among the encoded blocks that refer to the image fr110 when searching in a predetermined order. A block bk110 of the image fr110 represents a block at the same position as the block bk101, and a block bk111 refers to a motion vector of the block bk101 and represents a reference block of the block bk101.

  The block bk112 represents a block located at the same position as the block bk102, and the block bk113 represents a reference block of the block bk102 with reference to the motion vector of the block bk102.

  Thereby, it is possible to calculate the variation of the quantization parameter between the entire images between the similar blocks (block bk102, block bk113), and reflect this variation in the predicted value of the quantization parameter. In addition, the block selection unit 301 searches for encoded blocks in a predetermined order, and decodes information indicating which block is used by ending the search process when a block that references the reference image fr110 is found. There is no need to send to the side.

  FIG. 5 is a diagram showing a block selection example (No. 2). In the example illustrated in FIG. 5, the block selection unit 301 selects the upper left block bk210 of the image fr110 and the block bk202 moved by the motion vector mv201 from the upper left block bk201 of the image fr101. The motion vector mv201 is a reverse direction vector of the motion vector mv210 of the block bk101.

  The block selection unit 301 sets the similar block as the upper left block bk210 of the reference image, and selects the encoded block bk202 at the position indicated by the backward vector mv201 of the motion vector from the upper left block bk201 of the processing target image.

  As a result, it is possible to calculate the variation of the quantization parameter between the entire images between the blocks estimated to be similar (block bk202, block bk210), and to reflect this variation in the predicted value of the quantization parameter. . In addition, the block selection unit 301 does not need to perform a search process, so the processing load can be reduced.

  FIG. 6 is a diagram showing a block selection example (No. 3). In the example illustrated in FIG. 6, the block selection unit 301 searches for an encoded block having the same motion vector as the motion vector of the processing target block bk101. In the example illustrated in FIG. 6, the block bk301 represents an encoded block having the same motion vector as the block bk101.

  A block bk310 illustrated in FIG. 6 represents a block located at the same position as the block bk301. A block bk311 is referred to by a motion vector of the block bk301 and represents a reference block of the block bk301.

  The block selection unit 301 selects an encoded block bk301 having the same motion vector as the processing target block bk101 and a similar block bk311 in the reference image referred to by the motion vector of the encoded block bk301.

  As a result, the variation of the quantization parameter between the entire images can be calculated between similar blocks (block bk301, block bk311), and this variation can be reflected in the predicted value of the quantization parameter.

  Note that the encoded block, the similar block in the reference image, and the like are more preferably blocks having the same size as the processing target block.

  The block selection unit 301 basically performs the selection shown in FIG. 4, and when there is no block that references the same image as the reference image of the processing target block among the encoded blocks, the selection shown in FIG. 5 is performed. You may make it perform.

  Further, when the selection shown in FIG. 5 is performed, the backward vector does not necessarily fit within the screen. At this time, the block selection unit 301 may use the block bk201.

<Operation>
Next, the operation of the image encoding device 10 in the first embodiment will be described. FIG. 7 is a flowchart illustrating an example of a quantization parameter predicted value calculation process according to the first embodiment. The process shown in FIG. 7 is a predicted value calculation process in one process target block (for example, CU).

  In step S101, the quantization parameter prediction unit 207 determines whether the processing target block has been inter predicted. If the processing target block is inter prediction (step S101-YES), the process proceeds to step S102, and if the processing target block is not inter prediction (step S101-NO), the prediction value calculation process is terminated.

  In step S102, the quantization parameter prediction unit 207 obtains the Qp value (Qp_r) of the reference block that is the reference destination of the motion vector of the processing target block.

  In step S103, the quantization parameter prediction unit 207 determines whether there is a block that refers to a block in the reference image that is referred to by the motion vector of the processing target block among the encoded blocks of the processing target image. If there is a block that refers to a block in the reference image (step S103—YES), the process proceeds to step S104. If there is no block that refers to a block in the reference image (step S103—NO), the process proceeds to step S107.

  In step S104, the quantization parameter prediction unit 207 obtains the Qp value (Qp_cf) of the encoded block that refers to the reference image.

  In step S105, the quantization parameter prediction unit 207 obtains the Qp value (Qp_rf) of the similar block in the reference image referred to by the encoded block.

  In step S106, the quantization parameter prediction unit 207 calculates a prediction value of the quantization parameter using Expression (1).

  In step S107, the quantization parameter prediction unit 207 obtains the Qp value (Qp_rf) of the upper left block of the reference image.

  In step S108, the quantization parameter prediction unit 207 determines whether the end point of the backward vector of the motion vector of the processing target image is within the image from the upper left block of the processing target image. If the end point is in the image (step S108—YES), the process proceeds to step S109, and if the end point is not in the image (step S108—NO), the process proceeds to step S110.

  In step S109, the quantization parameter prediction unit 207 obtains the Qp value (Qp_cf) of the encoded block referenced by the backward vector.

  In step S110, the quantization parameter prediction unit 207 obtains the Qp value (Qp_cf) of the upper left encoded block in the processing target image.

  After steps S109 and S110, a predicted value of the quantization parameter of the processing target block is generated in step S106.

  As described above, according to the first embodiment, the variation of the quantization parameter between the entire images can be calculated between similar blocks, and by reflecting this variation on the predicted value of the quantization parameter, The accuracy of the predicted value can be improved.

[Example 2]
Next, the image decoding apparatus 40 in Example 2 is demonstrated. The image decoding device 40 according to the second embodiment is a device that decodes the bitstream encoded by the image encoding device 10 according to the first embodiment.

<Configuration>
FIG. 8 is a block diagram illustrating an example of a schematic configuration of the image decoding device 40 according to the second embodiment. As illustrated in FIG. 8, the image decoding device 40 includes an entropy decoding unit 401, an inverse quantization unit 402, an inverse orthogonal transform unit 403, an intra prediction unit 404, a decoded information storage unit 405, an inter prediction unit 406, and a predicted image selection unit. 407, a decoded image generation unit 408, a deblocking filter unit 409, a loop filter unit 410, and a frame memory 411. An outline of each part will be described below.

  When a bit stream is input, the entropy decoding unit 401 performs entropy decoding corresponding to the entropy encoding of the image encoding device 10. The prediction error signal decoded by the entropy decoding unit 401 is output to the inverse quantization unit 402. Also, the decoded filter coefficient, the decoded motion vector in the case of inter prediction, and the like are output to the decoded information storage unit 405.

  In the case of intra prediction, the entropy decoding unit 401 notifies the intra prediction unit 404 to that effect. In addition, the entropy decoding unit 401 notifies the prediction image selection unit 407 whether the decoding target image is inter predicted or intra predicted.

  The inverse quantization unit 402 performs an inverse quantization process on the output signal from the entropy decoding unit 401. The inverse quantization unit 402 generates a prediction value of the quantization parameter in the same manner as in the first embodiment, and obtains the quantization parameter. The inverse quantization unit 402 acquires the motion vector of the processing target block and the decoded block in the processing target image from the decoding information storage unit 405 in order to generate a prediction value of the quantization parameter.

  The inverse quantization unit 402 has a buffer that stores data used for generating a predicted value. This buffer stores a quantization parameter of the reference image. The inverse quantization unit 402 performs inverse quantization using the obtained quantization parameter. The inversely quantized output signal is output to the inverse orthogonal transform unit 403.

  The inverse orthogonal transform unit 403 performs an inverse orthogonal transform process on the decoded block of the output signal from the inverse quantization unit 402 to generate a residual signal. The residual signal is output to the decoded image generation unit 408.

  The intra prediction unit 404 generates a predicted image using a plurality of prediction directions from the peripheral pixels already decoded of the decoding target image acquired from the frame memory 411. Information about the prediction direction and the prediction block used to generate the prediction image is output to the inverse orthogonal transform unit 403 as prediction information.

  The decoding information storage unit 405 stores decoding information such as filter coefficients, motion vectors, and division modes of the decoded loop filter. The motion vector used for generating the predicted value of the quantization parameter is acquired by the inverse quantization unit 402.

  The inter prediction unit 406 performs motion compensation on the reference image data acquired from the frame memory 411 using the motion vector and the division mode acquired from the decoding information storage unit 405. Thereby, block data as a motion-compensated reference image is generated.

  The predicted image selection unit 407 selects either one of the intra predicted image and the inter predicted image. The selected block data is output to the decoded image generation unit 408.

  The decoded image generation unit 408 adds the predicted image output from the predicted image selection unit 407 and the residual signal output from the inverse orthogonal transform unit 403 to generate a decoded image. The generated decoded image is output to the deblocking filter unit 409.

  The deblocking filter unit 409 applies a filter for reducing block distortion to the decoded image output from the decoded image generation unit 408 and outputs the result to the loop filter unit 410.

  The loop filter unit 410 performs filter processing for each predetermined size of the decoded image using the filter coefficient acquired from the decoded information storage unit 405. The predetermined size is, for example, an inverse orthogonal transform size. The decoded image after the loop filter processing is output to the frame memory 411. Note that the decoded image after the loop filter may be output to a display device or the like.

  The frame memory 411 stores a decoded image that becomes a reference image. The decoded information storage unit 405 and the frame memory 411 are configured separately, but they may be the same storage unit.

  The above-described configuration of the image decoding device 40 is merely an example, and the configuration may be changed depending on the mounting method. For example, a plurality of units may be configured together.

  Accordingly, in the second embodiment, the bitstream encoded by the image encoding device 10 according to the first embodiment can be appropriately decoded.

[Example 3]
Next, an image processing apparatus according to the third embodiment will be described. The image processing apparatus collectively refers to the image encoding apparatus and the image decoding apparatus as an image processing apparatus. In the third embodiment, a case where each process of the above-described embodiment is implemented by software will be described.

<Configuration>
FIG. 9 is a block diagram illustrating an example of a schematic configuration of the image processing apparatus 50 according to the third embodiment. The image processing apparatus 50 illustrated in FIG. 9 includes at least a control unit 501, a main storage unit 502, an auxiliary storage unit 503, a communication unit 504, and a recording medium I / F unit 505. Each unit is connected via a bus so that data can be transmitted / received to / from each other.

  The control unit 501 is a CPU (Central Processing Unit) that controls each device, calculates data, and processes in a computer. The control unit 501 is an arithmetic device that executes programs stored in the main storage unit 502 and the auxiliary storage unit 503. The control unit 501 receives data from the communication unit 504 and each storage unit, calculates, processes, and outputs the data. And output to each storage unit.

  In addition, the control unit 501 can execute the above-described processing by executing a program for performing any one of the above-described embodiments stored in the auxiliary storage unit 503, for example.

  The main storage unit 502 is a ROM (Read Only Memory), a RAM (Random Access Memory), or the like, and a storage device that stores or temporarily stores programs and data such as an OS and application software that are basic software executed by the control unit 501. It is.

  The auxiliary storage unit 503 is an HDD (Hard Disk Drive) or the like, and is a storage device that stores data related to application software or the like. The auxiliary storage unit 503 may store a program acquired from the recording medium 506 or the like.

  The communication unit 504 performs wired or wireless communication. The communication unit 504 may store a program transmitted from a server or the like in the auxiliary storage unit 503, for example.

  A recording medium I / F (interface) unit 505 is an interface between the image processing apparatus 50 and a recording medium 506 (for example, a flash memory) connected via a data transmission path such as a USB (Universal Serial Bus).

  A predetermined program is stored in the recording medium 506, and the program stored in the recording medium 506 is installed in the image processing apparatus 50 via the recording medium I / F unit 505. The installed predetermined program can be executed by the image processing apparatus 50.

  For example, the decoded image storage unit 110 illustrated in FIG. 1, the decoded information storage unit 405, and the frame memory 411 illustrated in FIG. 8 can be realized by the main storage unit 502 or the auxiliary storage unit 503, for example. Each unit other than the storage units shown in FIGS. 1 and 8 can be realized by, for example, the control unit 501 and the main storage unit 502 as a working memory.

  It is also possible to record the program on the recording medium 506 and cause the computer or portable terminal to read the recording medium 506 on which the program is recorded to realize the above-described processing.

  The recording medium 506 is a recording medium that records information optically, electrically, or magnetically, such as a CD-ROM, flexible disk, magneto-optical disk, etc., and information is electrically stored, such as a ROM or flash memory. Various types of recording media such as a semiconductor memory for recording can be used. Further, the processes described in the above embodiments may be implemented in one or a plurality of integrated circuits.

  Each embodiment has been described in detail above. However, the present invention is not limited to the specific embodiment, and various modifications and changes other than the above-described modification are possible within the scope described in the claims. .

DESCRIPTION OF SYMBOLS 10 Image encoding apparatus 40 Image decoding apparatus 50 Image processing apparatus 103 Quantization part 104 Entropy encoding part 201 Quantization control part 203 Quantization parameter determination part 204 Quantization processing part 207 Quantization parameter prediction part 209 Parameter encoding part 301 Block selection unit 303 Prediction unit 402 Inverse quantization unit 501 Control unit 502 Main storage unit

Claims (7)

An image encoding device that performs frequency conversion for each block into which an image is divided and performs quantization using a quantization parameter,
An encoded block in an image including a processing target block for which inter-screen prediction has been performed, and a similar block similar to the encoded block in a reference image referred to by a motion vector of the processing target block are encoded A selection unit for selecting in consideration of the movement of the converted block;
A value obtained by adding the difference value of the quantization parameter of the encoded block selected by the selection unit and the similar block to the quantization parameter of the block referred to by the motion vector of the processing target block is the value of the processing target block. A predictor for predicting the quantization parameter;
An image encoding device comprising: The selection unit includes:
The image encoding device according to claim 1, wherein the encoded block is searched in order, and when the motion vector of the encoded block refers to a block in the reference image, the block is set as the similar block. The selection unit includes:
The image coding apparatus according to claim 1, wherein the similar block is an upper left block of the reference image, and an encoded block at a position referred to by a backward vector of the motion vector is selected from the upper left block. The selection unit includes:
The image encoding device according to claim 1, wherein an encoded block having the same motion vector as that of the processing target block and a similar block in the reference image to which a motion vector of the encoded block refers are selected. An image decoding device for decoding a stream encoded by the image encoding device according to any one of claims 1 to 4,
A decoding unit for entropy decoding the stream;
An inverse quantization unit that performs an inverse quantization process using the difference value of the decoded quantization parameter and the predicted value of the generated quantization parameter;
An image decoding apparatus comprising: In order to perform frequency conversion for each block into which an image is divided and perform quantization using quantization parameters,
An encoded block in an image including a processing target block for which inter-screen prediction has been performed, and a similar block similar to the encoded block in a reference image referred to by a motion vector of the processing target block are encoded A selection step for selecting in consideration of the movement of the converted block;
A value obtained by adding the difference value of the quantization parameter of the selected coded block and the similar block to the quantization parameter of the block referred to by the motion vector of the processing target block is the quantization parameter of the processing target block. An image encoding program for executing a prediction step to obtain a prediction value. In order to decode the stream encoded by the image encoding device according to any one of claims 1 to 4,
A decoding step for entropy decoding the stream;
An inverse quantization step for performing an inverse quantization process using a difference value of the decoded quantization parameter and a predicted value of the generated quantization parameter;
An image decoding program for executing

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