JP2010193401A - Image encoding method and apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To facilitate efficient encoding of pixels which are not displayed on a display. <P>SOLUTION: An image encoding method includes: an area detection step of detecting whether a pixel block for encoding is constituted by a first area which is displayed on an image display and a second area which is not displayed on the image display; and a motion vector detection step of detecting a motion vector only about the first area, when the pixel block for encoding is a pixel block including both the first and second areas as a result of a detection in the area detection step, wherein in an encoding step the pixel block including both the first and second areas is encoded by using the motion vector detected in the motion vector detection step. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an image encoding method and an image encoding apparatus, and more particularly to a technique suitable for use in improving the encoding efficiency of image data.

  In recent years, the digitalization of information related to multimedia has been rapidly progressing, and the demand for higher image quality of video information has increased accordingly. As a specific example, in the broadcast media, there is a transition from the conventional SD of 720 × 480 pixels to HD of 1920 × 1080 pixels. However, since this demand for higher image quality causes an increase in digital data at the same time, there is a need for compression encoding technology and decoding technology that exceed conventional performance.

  In response to these demands, standardization of an encoding / compression method using inter-frame prediction using correlation between images is underway by activities of ITU-T SG16 and ISO / IEC JTC1 / SC29 / WG11. Among these, H. is an encoding method that is said to realize the most efficient encoding at present. H.264 / MPEG-4 PART10 (AVC, hereinafter referred to as H.264). H. H.264 encoding / decoding specifications are disclosed in, for example, Patent Document 1.

  This H. As one of the technologies newly introduced in H.264, a plurality of types of macroblock partitions (hereinafter referred to as macroblock partitions) serving as encoding units are prepared, the amount of motion is detected in finer pixel units, There is a technology to further reduce the amount.

Here, the macroblock partition will be described in detail with reference to FIG.
As shown in (1) to (4) of FIG. 2 (a), H.264 divides a macro block of 16 × 16 pixels, which is an encoding processing unit having the size used in MPEG2, and minimizes the minimum. It is possible to select from four types of macroblock types that are 8 × 8 pixels.

  Further, the 8 × 8 pixel macroblock type shown in (4) of FIG. 2A is divided into smaller sub-macroblock types as shown in (5) to (8) of FIG. 2B. be able to. It is possible to divide into four types of sub-macroblock types up to a minimum of 4 × 4 pixels.

  That is, the macroblock partition is selected from 19 types. That is, 3 (number of macroblock partitions not subject to sub-macroblock partition) +4 (number of macroblocks subject to sub-macroblock partition) × 4 (number of sub-macroblock partitions) = 19 types are selected. . As a result, it becomes possible to search for motion information in finer image units, and the accuracy of motion information is improved.

JP 2005-167720 A

  In H.264, the size of a macroblock serving as a coding unit is 16 × 16 pixels. Therefore, when encoding a 1920 × 1080 pixel HD image, the vertical 1080 pixels are not divisible by 16, so when encoding sequentially from the top of the screen, an extra 8 pixels that are not displayed on the display at the bottom of the screen are encoded. (See FIG. 3).

Conventionally, since 8 pixels that are not displayed on the display are encoded in the same manner as the pixels that are displayed on the display, it has been an obstacle to improving the encoding efficiency.
An object of the present invention is to make it possible to easily and efficiently perform encoding of pixels that are not displayed on a display in view of the above-described problems.

An image encoding method of the present invention is an image encoding method including an encoding step of performing motion compensation encoding by detecting a motion vector for each of a plurality of pixel blocks constituting an encoding target picture. A region detecting step for detecting whether or not each pixel block is composed of a first region displayed on the image display device and a second region not displayed on the image display device, and detection in the region detecting step As a result, when the pixel block to be encoded is a pixel block including both the first region and the second region, a motion vector detection step for detecting a motion vector only for the first region In the encoding step, the first region and the second region are detected using the motion vector detected in the motion vector detection step. Characterized by coding a pixel block containing both pass.
Another feature of the image coding method according to the present invention is that a macroblock constituting a picture to be coded is divided into smaller blocks, and a motion vector is detected for each of the macroblock and the block. In the image encoding method including an encoding step of performing motion compensation encoding, a first area in which a macroblock to be encoded is displayed on the image display device, and a second area that is not displayed on the image display device A region detecting step for detecting whether or not the region is composed of the first region, and in the region detecting step, the macroblock to be encoded is composed of the first region and the second region. In the encoding step, the motion vector and the macroblock division method are determined in accordance with the pixels in the first area. And, wherein applying a dividing method determined uniquely with respect to the second area in accordance with the first dividing method determined in the region, the macroblock of the encoding target, characterized in that encoding.
Another feature of the image coding method of the present invention is that motion compensation coding is performed by detecting a motion vector for each of a plurality of 16 × 16 pixel macroblocks constituting a picture to be coded. In the image encoding method including the encoding step, when the encoding target macroblock is a macroblock located at the lower end of the screen in the encoding target picture, the upper 16 × 8 of the encoding target macroblock A motion vector detecting step of detecting a motion vector by searching with a pixel, and the encoding step encodes the encoding target macroblock using the motion vector detected in the motion vector detecting step; It is characterized by doing.

An image encoding apparatus according to the present invention is an image encoding apparatus having encoding means for performing motion compensation encoding by detecting a motion vector for each of a plurality of pixel blocks constituting an encoding target picture. Detection means for detecting whether or not each pixel block is composed of a first area displayed on the image display device and a second area not displayed on the image display device, and detection by the area detection means As a result, when the pixel block to be encoded is a pixel block including both the first region and the second region, a motion vector detection unit that detects a motion vector only for the first region. And the encoding means uses both the first area and the second area using the motion vector detected by the motion vector detecting means. Characterized by coding a pixel block including.
Another feature of the image coding apparatus according to the present invention is that a macroblock constituting a picture to be coded is divided into smaller blocks, and a motion vector is detected for each of the macroblock and the block. In the image coding apparatus having coding means for performing motion compensation coding, a first area in which a macroblock to be coded is displayed on the image display apparatus and a second area that is not displayed on the image display apparatus Region detecting means for detecting whether or not the region is composed of the first region and the second region, wherein the encoding target macroblock is composed of the first region and the second region. The encoding means determines a motion vector and a macroblock division method according to the pixels of the first region, and By applying the dividing method is uniquely determined according to the division method determined in the first region to the second region, the macroblock of the encoding target, characterized in that encoding.
Another feature of the image coding apparatus according to the present invention is that motion compensation coding is performed by detecting a motion vector for each of a plurality of 16 × 16 pixel macroblocks constituting a picture to be coded. In the image encoding device having encoding means, when the encoding target macroblock is a macroblock located at the lower end of the screen in the encoding target picture, the upper 16 × 8 of the encoding target macroblock Motion vector detecting means for detecting a motion vector by searching with pixels, and the encoding means encodes the encoding target macroblock using the motion vector detected by the motion vector detecting means. It is characterized by that.
Features.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to improve the encoding efficiency of the image data of the part which is not displayed on a display, and can provide the image encoding apparatus which has high encoding efficiency.

1 is a block diagram illustrating a schematic configuration of an image encoding device according to a first embodiment of the present invention. It is a figure for demonstrating the macroblock partition and submacroblock partition in embodiment of this invention. It is a figure for demonstrating the subject of this invention and demonstrating the macroblock of the protrusion part of a screen. It is a flowchart which shows embodiment of this invention and demonstrates the operation | movement of the inter coding prediction system of an image coding apparatus.

(First embodiment)
Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In the present embodiment, as shown in FIG. 3, since 1920 × 1080 pixels are encoded, it is necessary to encode 8 pixels that are not displayed on the display 31 at the lower end of the screen of the image display device. In addition, it is assumed that the image encoding device according to the present embodiment starts encoding from the upper left of the screen and sequentially encodes toward the lower right of the screen.

FIG. 1 is a block diagram illustrating a configuration example of an image encoding device 100 according to the present embodiment.
In FIG. 1, 1 is an image input unit for inputting current video data, and 2 is a current frame storage unit for temporarily storing current video data.

  Reference numeral 3 denotes a reference frame candidate storage unit that holds the restored image data on which block boundary correction processing, which will be described later, has been performed, as a reference image of the predicted image information. 4 is an intra prediction encoding unit that divides image data currently stored in the frame storage unit 2 into a plurality of pixel blocks, predicts image data of each pixel block from pixels around the block, and generates predicted image information. .

  5 divides the current image data input from the intra prediction encoding unit 4 into a plurality of pixel blocks. Then, in each pixel block, a motion search process for detecting a position having a high correlation with the reference frame candidate stored in the reference frame candidate storage unit 3 is performed, and the difference data at the position is detected as motion information between frames. It is a detection unit.

  Reference numeral 6 denotes an inter prediction encoding unit that performs motion compensation for generating predicted image information of the current image data from the reference frame and the motion information output from the motion detection unit 5. Reference numeral 7 denotes a subtracter for subtracting predicted image information to be described later. A switch unit 8 selects prediction information.

  A DCT unit 9 performs integer orthogonal transformation on the difference data of the image. Reference numeral 10 denotes a quantization unit that performs quantization at a predetermined quantization scale on the transform coefficient subjected to integer orthogonal transform. Reference numeral 11 denotes an entropy coding unit that compresses data by performing entropy coding processing on the transform coefficient quantized by the quantization unit 10.

  Reference numeral 12 denotes an inverse quantization unit that performs a predetermined inverse quantization process on the transform coefficient quantized by the quantization unit 10. Reference numeral 13 denotes an IDCT unit that performs inverse integer orthogonal transform for returning the transform coefficient inversely quantized by the inverse quantization unit 12 to the original image data space. Reference numeral 14 denotes an adder for adding predicted image information described later to the image difference information returned to the image data space.

  Reference numeral 15 denotes a decoded image storage unit that stores image data restored by predicted image information described later. Reference numeral 16 denotes a deblocking filter that corrects discontinuity in boundary data in units of predetermined pixel blocks with respect to image data restored by predicted image information described later. Reference numeral 17 denotes a screen lower end detection unit. The screen lower end detection unit 17 functions as an area detection unit, and counts the number of pixel blocks input from the current frame storage unit 2. Then, the screen lower end detection unit 17 determines whether or not the pixel block composed of the first region displayed on the image display device and the second region not displayed on the image display device has been reached, that is, the screen lower end. It is detected whether or not the pixel block located at is being encoded.

Next, an outline of the flow of the encoding process in the present embodiment will be described with reference to the block diagram of FIG.
Image data of video information input from the image input unit 1 is temporarily stored in the current frame storage unit 2. Next, the intra prediction encoding unit 4 divides the block into 16 × 16 pixel blocks (macroblocks) serving as encoding units. Next, the prediction image information and difference data, which are sequentially transmitted from the intra prediction encoding unit 4 to the subtractor 7, subtract the prediction image information in the subtractor 7, and are difference information between the encoding target picture and the reference picture pixel. Is generated. A method for generating predicted image information will be described later. Further, a flag indicating that the macro block is transmitted to the subtracter 7 is transmitted from the current frame storage unit 2 to the screen lower end detection unit 17.

  The difference data output from the subtracter 7 is subjected to integer orthogonal transformation in the DCT unit 9 and is orthogonally transformed from a general image space to a space of a transformation coefficient with increased energy concentration. The transform coefficient of the difference data transformed by the DCT unit 9 is quantized by the quantization unit 10 according to the orthogonal transform component with a predetermined step width.

  The transform coefficient data quantized by the quantization unit 10 is compression-encoded by the entropy encoding unit 11. Further, the entropy encoding unit 11 also multiplexes and compresses the identifier of the frame number referred to in inter-encoding described later.

Next, prediction image information generation processing will be described.
Predictive image information includes an intra prediction encoding method that is generated from data in the current image at the time of input, and an inter encoding method that is generated from frame image data other than the current image at the time of input.
First, an intra-coded prediction method in which processing is closed in the current input image will be described.
With respect to the transform coefficient quantized by the quantization unit 10, the inverse quantization unit 12 restores the transform coefficient. Then, the restored transform coefficient is returned to the original image data space by the IDCT unit 13 and restored as difference data from the predicted image information.

  By adding predicted image information, which will be described later, to the restored difference data restored in the IDCT unit 13 by the adder 14, restored image data of the input image is obtained. However, the restored image data at this time is an image that is slightly degraded from the input image data due to an error in prediction information described later or a quantization error in the quantization process performed in the quantization unit 10. .

  The restored image data is once taken into the decoded image storage unit 15. Then, the intra-prediction encoding unit 4 divides the restored image data captured by the decoded image storage unit 15 into predetermined block units, and the restored image data in each block is determined from the peripheral pixel values of the block. Predict. The intra prediction encoding unit 4 calculates the prediction value as prediction image information and sends it to the switch 8.

  In the switch 8, the switch is switched to the terminal 8a or 8b by a controller (not shown) according to the prediction method of the prediction image information. In the case of the intra prediction encoding method described above, the switch is connected to the terminal 8a, and the data obtained by the calculation method based on the intra prediction method is transmitted as the prediction image information. The intra prediction image information is sent to the subtractor 7 and the adder 14 and is used to generate restored image data and predicted image difference data.

  Next, an inter-coded prediction method for generating predicted image information using a reference frame image different from the current input image will be described with reference to the flowchart of FIG. In this embodiment, for simplicity of explanation, the macro block partition is not divided into sub macro block types, and the 8 × 8 macro block type is set as the minimum macro block partition. In addition, since it is the same as an intra prediction encoding system and the adder 14, description is abbreviate | omitted.

  The restored image data obtained by the adder 14 is temporarily stored in the decoded image storage unit 15 and then sent to the deblocking filter 16 in order to eliminate the discontinuity of data at the block unit boundary described later.

  The deblocking filter 16 performs a predetermined filter process on pixel data adjacent to the block boundary, and suppresses discontinuity of the data on the block boundary. As described above, the restored image data is a deteriorated image than the input image. In particular, the image data processed in a predetermined block unit in each processing is data discontinuity at the block boundary. Is likely to occur and the image is recognized as block distortion.

  Therefore, in order to reduce the block distortion, in this embodiment, the deblocking filter 16 is used to reduce the block distortion at the block boundary. The restored image data subjected to boundary processing by the deblocking filter 16 is stored in the reference frame candidate storage unit 3 and used for motion vector detection performed by the motion detection unit 5.

  The motion detection unit 5 searches for a motion vector indicating a position having a strong correlation between the encoding target macroblock input from the current frame storage unit 2 and the reference frame transmitted from the reference frame candidate storage unit 3. At this time, the motion vector search method is switched according to whether the screen is at the lower end. In the present embodiment, each element in the image is processed as one element of 16 × 16 pixels, and by detecting vector data indicating in which direction and how much the image moves relative to the image of the preceding and following frames, Motion compensation coding is enabled.

First, as shown in step S401 of FIG. 4, it is detected whether or not the macroblock of the encoding target picture is the lower end of the screen. If it is not the lower end of the screen, the process proceeds to step S402. .
In the vector search when the screen is not at the lower end performed in step S402, the motion vector search is first performed with a 16 × 16 macroblock type to search for a position having a strong correlation between the encoding target image and the reference frame. As a method for determining a position having a strong correlation with the reference frame, a method of taking a difference between each pixel of the macroblock and the reference frame and setting a position having the smallest absolute value sum of the differences as a position having a strong correlation is cited. However, the method is not limited. When the search with the 16 × 16 macroblock type is completed, the search with the smaller macroblock types such as 16 × 8, 8 × 16, and 8 × 8 is sequentially performed.

  Next, proceeding to step S403, the position determined to have the strongest correlation for each macroblock type is determined as a motion vector. Then, among the macroblock types, the macroblock type having the strongest correlation with the reference frame is set as the macroblock type of the macroblock to be encoded, and the vector partition of the upper macroblock is determined.

  Then, it progresses to step S404 and sends information about the motion vector determined in step S403 to the inter prediction encoding unit 6 and the entropy encoding unit 11. At the same time, the reference frame identification information used for generating the motion information is also sent to the inter prediction encoding unit 6 and the entropy encoding unit 11.

  The inter prediction encoding unit 6 calls the restored image data of the reference frame corresponding to the reference frame identification information described above from the reference frame candidate storage unit 3, and generates predicted image information of the current image from the restored image data and the motion vector. To do. As described above, inter prediction encoding is different from intra prediction encoding in that prediction image information is generated by referring to a frame different from the current image.

  The inter prediction image information generated by the inter prediction encoding unit 6 is sent to the subtractor 7 and the adder 14 via the terminal 8b of the switch 8, and is used to generate restored image data and predicted image difference data. . Thereafter, the process proceeds to step S405, and the entropy encoding unit 11 performs compression encoding.

  On the other hand, as a result of the detection in step S401, when the encoding target picture reaches the lower end of the screen and is a macroblock including both the first area and the second area, the process proceeds to step S406. In step S406, first, a motion vector search is performed only on the upper 16 × 8 pixels where the encoding target image exists, and a position having a strong correlation between the encoding target image and the reference frame is searched. When the search for the upper 16 × 8 pixels of the encoding target macroblock is completed, the search for two 8 × 8 pixels obtained by dividing the upper 16 × 8 is sequentially performed. When the motion vector search is completed, the process proceeds to step S407.

  In step S407, the position determined to have the strongest correlation for each macroblock type is determined as a motion vector. Next, the pixel size used in the search with the pixel having the stronger correlation with the reference frame is determined as the upper macroblock type between the search with 16 × 8 pixels and the search with 8 × 8 pixels.

  Subsequently, in step S408, it is determined whether or not the upper macroblock type of the encoding target macroblock determined in step S407 is 8 × 8. As a result of this determination, if the upper macroblock type of the encoding target macroblock determined in step S407 is 16 × 8, the process proceeds to step S409, and the macroblock type of the encoding target macroblock is determined to be 16 × 16. To do.

  On the other hand, as a result of the determination in step S408, if the upper macroblock type of the determined encoding target macroblock is 8 × 8, the process proceeds to step S410, and the macroblock type of the encoding target macroblock is set to 8 × 16. decide.

  In this way, the motion vector and macroblock division method at the lower end of the screen can be simply searched for only the upper 16 × 8 pixels. Specifically, a macroblock type uniquely determined according to the macroblock type determined by the upper 16 × 8 pixels can be applied to the lower 16 × 8 pixel region. Therefore, the number of searches can be reduced as compared with the case where the search is performed with normal 16 × 16 pixels. In addition, since the macroblock type can be limited to two of 16 × 16 or 8 × 16, it is possible to suppress the generation of vector code amount due to useless partitioning.

  Next, it progresses to step S411 and the following processes are performed. That is, the motion vector determined in step S409 or step S410 is sent to the inter prediction encoding unit 6 and the entropy encoding unit 11. At the same time, the reference frame identification information used for generating the motion information is also sent to the inter prediction encoding unit 6 and the entropy encoding unit 11.

  The inter prediction encoding unit 6 calls the restored image data of the reference frame corresponding to the reference frame identification information from the reference frame candidate storage unit 3, and predicts the predicted image information of the current image from the restored image data and the motion information. Also, the first area is encoded according to the macroblock division method determined according to the pixels of the first area. Further, the second region is encoded by applying a division method uniquely determined according to the macroblock division method of the first region to the second region.

  As described above, inter prediction encoding is different from intra prediction encoding in that prediction image information is generated by referring to a frame different from the current image. The generated inter-system prediction image information is connected to the terminal 8b by the switch 8 and is sent to the subtractor 7 and the adder 14, and is used to generate restored image data and predicted image difference data.

  As described above, since the user's eyes are not touched, generation of useless code amount can be suppressed by setting the difference to 0 for the lower 16 × 8 pixels that do not need to worry about image quality. In this embodiment, the case where the lower 16 × 8 pixels are not touched by the user has been described as an example. However, the present invention is applied regardless of the number of pixels not touched by the user and the positions of the upper and lower portions. Can do.

  In this embodiment, the case where four types of 16 × 16, 16 × 8, 8 × 16, and 8 × 8 are used as macroblock partitions has been described as an example. However, the present embodiment relates to the number of macroblock partitions and the number of types. The present invention can be applied.

(Other embodiments according to the present invention)
Each means constituting the image coding apparatus according to the above-described embodiment of the present invention can be realized by operating a program stored in a RAM or ROM of a computer. This program and a computer-readable recording medium recording the program are included in the present invention.

  In addition, the present invention can be implemented as, for example, a system, apparatus, method, program, storage medium, or the like. Specifically, the present invention may be applied to a system including a plurality of devices. The present invention may be applied to an apparatus composed of a single device.

  In the present invention, a software program (in the embodiment, a program corresponding to the flowchart shown in FIG. 4) for executing each step in the above-described image encoding method is directly or remotely supplied to a system or apparatus. In addition, this includes a case where the system or the computer of the apparatus is also achieved by reading and executing the supplied program code.

  Accordingly, since the functions of the present invention are implemented by computer, the program code installed in the computer also implements the present invention. In other words, the present invention includes a computer program itself for realizing the functional processing of the present invention.

  In that case, as long as it has the function of a program, it may be in the form of object code, a program executed by an interpreter, script data supplied to the OS, and the like.

  Various recording media can be used as a recording medium for supplying the program. For example, floppy (registered trademark) disk, hard disk, optical disk, magneto-optical disk, MO, CD-ROM, CD-R, CD-RW, magnetic tape, nonvolatile memory card, ROM, DVD (DVD-ROM, DVD- R).

  As another program supply method, a browser on a client computer is used to connect to an Internet home page. The computer program itself of the present invention or a compressed file including an automatic installation function can be downloaded from the homepage by downloading it to a recording medium such as a hard disk.

  It can also be realized by dividing the program code constituting the program of the present invention into a plurality of files and downloading each file from a different homepage. That is, the present invention includes a WWW server that allows a plurality of users to download a program file for realizing the functional processing of the present invention on a computer.

  In addition, the program of the present invention is encrypted, stored in a storage medium such as a CD-ROM, distributed to users, and key information for decryption is downloaded from a homepage via the Internet to users who have cleared predetermined conditions. Let It is also possible to execute the encrypted program by using the key information and install the program on a computer.

  In addition to the functions of the above-described embodiments being realized by the computer executing the read program, the OS running on the computer may perform part or all of the actual processing. The functions of the above-described embodiments can be realized.

  Further, the program read from the recording medium is written in a memory provided in a function expansion board inserted into the computer or a function expansion unit connected to the computer. Thereafter, the CPU of the function expansion board or function expansion unit performs part or all of the actual processing based on the instructions of the program, and the functions of the above-described embodiments are realized by the processing.

DESCRIPTION OF SYMBOLS 1 Image input part 2 Current frame preservation | save part 3 Reference frame candidate preservation | save part 4 Intra prediction encoding part 5 Motion detection part 6 Inter prediction encoding part 7 Subtractor 8 Switch part 9 DCT part 10 Quantization part 11 Entropy encoding part 12 Inverse quantization unit 13 IDCT unit 14 Adder 15 Decoded image storage unit 16 Deblocking filter 17 Screen lower end detection unit 100 Image encoding device

Claims (10)

In an image encoding method having an encoding step of performing motion compensation encoding by detecting a motion vector for each of a plurality of pixel blocks constituting an encoding target picture,
A region detecting step for detecting whether or not the pixel block to be encoded is composed of a first region displayed on the image display device and a second region not displayed on the image display device;
As a result of the detection in the region detection step, when the pixel block to be encoded is a pixel block including both the first region and the second region, a motion vector is calculated only for the first region. A motion vector detecting step for detecting,
In the encoding step, a pixel block including both the first region and the second region is encoded using the motion vector detected in the motion vector detection step. Method.   In the encoding step, for pixel blocks including both the first area and the second area, difference information between a pixel in the second area and a reference picture pixel referred to in the motion compensation encoding The image encoding method according to claim 1, wherein encoding is performed with 0 set to 0. An image encoding method including an encoding step of performing motion compensation encoding by dividing a macroblock constituting an encoding target picture into smaller blocks and detecting a motion vector for each of the macroblock and the block. In
An area detection step of detecting whether or not the macroblock to be encoded is composed of a first area displayed on the image display device and a second area not displayed on the image display device;
In the region detection step, when it is detected that the macroblock to be encoded is composed of the first region and the second region, in the encoding step, the first region A motion vector and a macroblock division method are determined in accordance with the pixels of the first pixel, and a division method uniquely determined according to the division method determined in the first region is applied to the second region, An image encoding method, wherein a macroblock is encoded.   In the encoding step, a difference between a pixel in the second area and a pixel in a reference picture referred to in the motion compensation encoding for a macroblock composed of the first area and the second area 4. The image encoding method according to claim 3, wherein the information is encoded with 0. In an image encoding method having an encoding step of performing motion compensation encoding by detecting a motion vector for each of a plurality of 16 × 16 pixel macroblocks constituting an encoding target picture,
When the encoding target macroblock is a macroblock located at the bottom of the screen of the encoding target picture, the motion for detecting the motion vector by searching in the upper 16 × 8 pixels of the encoding target macroblock A vector detection step,
In the encoding step, the macroblock to be encoded is encoded using the motion vector detected in the motion vector detection step. In an image coding apparatus having coding means for performing motion compensation coding by detecting a motion vector for each of a plurality of pixel blocks constituting a picture to be coded,
Area detecting means for detecting whether or not the pixel block to be encoded is composed of a first area displayed on the image display device and a second area not displayed on the image display device;
As a result of detection by the region detection means, when the pixel block to be encoded is a pixel block including both the first region and the second region, a motion vector is calculated only for the first region. Motion vector detecting means for detecting,
The encoding means encodes a pixel block including both the first area and the second area using a motion vector detected by the motion vector detection means. .   For the pixel block including both the first area and the second area, the encoding means calculates difference information between a pixel in the second area and a reference picture pixel referred to in the motion compensation encoding. The image encoding apparatus according to claim 6, wherein the encoding is performed with 0. Image coding apparatus having coding means for performing motion compensation coding by dividing a macroblock constituting a picture to be coded into smaller blocks and detecting a motion vector for each of the macroblock and the block In
An area detecting means for detecting whether or not the macroblock to be encoded is composed of a first area displayed on the image display device and a second area not displayed on the image display device;
When the area detecting means detects that the macro block to be encoded is composed of the first area and the second area, the encoding means According to pixels, a motion vector and a macroblock division method are determined, and a division method uniquely determined according to the division method determined in the first region is applied to the second region, so that the macro to be encoded An image encoding apparatus that encodes a block.   The encoding means includes difference information between a pixel of the second region and a pixel of a reference picture referred to in the motion compensation encoding for a macroblock composed of the first region and the second region. The image encoding apparatus according to claim 8, wherein encoding is performed with 0 being set to 0. In an image encoding device having encoding means for performing motion compensation encoding by detecting a motion vector for each of a plurality of 16 × 16 pixel macroblocks constituting an encoding target picture,
When the encoding target macroblock is a macroblock located at the bottom of the screen of the encoding target picture, the motion for detecting the motion vector by searching in the upper 16 × 8 pixels of the encoding target macroblock Having vector detection means,
The image encoding device, wherein the encoding unit encodes the encoding target macroblock using a motion vector detected by the motion vector detection unit.

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