Motion vector estimation apparatus and motion vector estimation method

A motion vector estimation apparatus that can reduce an amount of calculation for video coding processing and thus achieve a higher bit rate and lower consumption power, while contributing to improvement in image quality and coding efficiency include: a reduced picture generation unit which generates a reduced current picture to be coded and a reduced reference picture; a region partition unit which partitions a reduced current picture to be coded into regions and generates reduced region images; a region motion vector estimation unit which estimates a region motion vector of a reduced region image; a confidence level calculation unit which calculates a confidence level of a region motion vector; and a block size narrowing-down unit which narrows down candidate block sizes so as to determine a block size to be used for coding a current block to be coded, based on a region motion vector and a confidence level of the region motion vector.

BACKGROUND OF THE INVENTION

(1) Field of the Invention

The present invention relates to a motion vector estimation apparatus for estimating a motion vector of a current block to be coded in a current picture to be coded.

(2) Description of the Related Art

With the advances in semiconductor technology and the like, various coding schemes for video compression have been introduced to home video recorders. In particular, coding schemes such as MPEG-2, MPEG-4 and the like which exploit motion vectors between a number of pictures constituting a video sequence have been widely used.

A motion vector estimation apparatus using such a coding scheme estimates a motion vector between pictures on a block-by-block basis. Particularly, H.264/MPEG-4 AVC gives the encoder the ability to choose which block size, from among a number of block sizes, will be used for the most efficient coding (see, for example, Yoichi Yagasaki, et al., “Jisedai Dogazo Fugoka Hoshiki MPEG4 AVC/H.264 (MPEG-4 AVC/H.264: Next Generation Video Coding Standard)” Mar. 12, 2004). Therefore, differently from the conventional coding scheme using a fixed block size of 16×16 pixels, H.264/MPEG-4 AVC gives flexibility in coding images depending on the properties of the images, and thus better compression ratios can be gained.

As shown inFIG. 1AtoFIG. 1D, in H.264/MPEG-4 AVC, each macroblock of 16×16 pixels can be divided into macroblocks of 16×8, 8×16 or 8×8, each of which can have its own motion vector and reference picture. As shown inFIG. 1EtoFIG. 1H, each macroblock of 8×8 pixels can further be divided into sub-macroblocks of 8×4, 4×8 or 4×4 pixels.

As mentioned above, when a current picture to be coded is inputted, the conventional motion vector estimation apparatus estimates motion vectors for four types of macroblocks, calculates the prediction errors of predicted images (sum of absolute differences between the original images and the predicted images) predicted based on the reference images and the estimated motion vectors, and selects, as a block size to be used for coding, one of the four types of macroblocks which has the smallest error. Furthermore, if the block size of 8×8 pixels is selected, motion vectors are further estimated for four types of sub-macroblocks, and prediction errors are calculated for these sub-macroblocks. Then, one of the four types of sub-macroblocks which has the smallest error is selected as a block size to be used for coding.

In addition, a motion compensation block size determination method has been proposed in which a block size for motion compensation can be varied depending on edge information included in the image (see, for example, Japanese Laid-Open Patent Application No. 01-69181 Publication). In this motion compensation block size determination method, a picture is divided into small blocks and the number of edges in each small block is obtained. If the number of edges is smaller than a threshold value, these small blocks are combined into larger blocks until the number of edges in each larger block becomes greater than the threshold value, so that that block size is determined to be used for motion compensation.

However, in H.264/MPEG-4 AVC, as described above, since motion vectors are estimated for blocks of different sizes (four candidates as macroblock sizes and four candidates as sub-macroblock sizes) and the optimal block size is selected from among them in order to choose the best prediction method for efficient video coding, there is a problem that a large amount of calculation is required for coding, and thus such coding has a heavy processing load for the calculation and requires a large amount of power.

By the way, image degradation such as a block noise in a scene where there is a large amount of motion between pictures is less noticeable to human eyes than that in a static scene. Therefore, it may be possible to select larger blocks in the scene where image degradation is less noticeable and thus to reduce the amount of coding. However, since the above-mentioned motion compensation block size determination method combines small blocks into larger blocks according to the number of edges in each block, regardless of motion between pictures, smaller blocks are likely to be selected even in the scene where there is a large amount of motion between pictures. Therefore, there is a problem that selection of smaller blocks causes increase in coding amount.

SUMMARY OF THE INVENTION

So the present invention has been conceived in view of the above problems, and has an object to provide a motion vector estimation apparatus and a motion vector estimation method for reducing an amount of calculation for video coding processing and thus achieving a higher bit rate and lower consumption power, while contributing to improving image quality and coding efficiency.

In order to achieve the above object, the motion vector estimation apparatus according to the present invention is a motion vector estimation apparatus which selects, from among candidate block sizes, a block size to be used for coding a current block to be coded in a current picture to be coded, and estimates a motion vector of the current block using the selected block size, and this apparatus includes: a region partition unit which partitions the current picture into at least one region, and generates a region image; a region motion vector estimation unit which estimates a motion vector of the region image generated by the region partition unit, as a region motion vector, using a reference picture used for estimating a motion vector of the current block and the region image; a confidence level calculation unit which calculates a confidence level of the region motion vector, based on a predicted region image and the region image generated by the region partition unit, the predicted region image being generated from the region motion vector estimated by the region motion vector estimation unit and the reference picture; a block size narrowing-down unit which narrows down the candidate block sizes to a candidate block size, in the case where the following conditions are satisfied: the region motion vector estimated by the region motion vector estimation unit is greater than a first threshold value; and the confidence level of the region motion vector calculated by the confidence level calculation unit is higher than a second threshold value; and a motion vector estimation unit which estimates a motion vector of the current block using the candidate block size to which the candidate block sizes have been narrowed down by the block size narrowing-down unit.

Accordingly, processing for determining the optimal block size can be simplified. Therefore, it is possible to reduce an amount of calculation and power required for estimating motion vectors.

Here, the above-mentioned motion vector estimation apparatus may further include a reduced picture generation unit which generates a reduced current picture to be coded by reducing the number of pixels that constitute the current picture, and generates a reduced reference picture by reducing the number of pixels that constitute the reference picture. In this apparatus, the region partition unit may partition, into at least one region, the reduced current picture generated by the reduced picture generation unit, and generate a region image, and the region motion vector estimation unit may estimate a motion vector of the region image, as the region motion vector, based on the reduced reference picture generated by the reduced picture generation unit and the region image generated by the region partition unit. Accordingly, it is possible to reduce an amount of calculation required for estimating region motion vectors.

The above-mentioned reduced picture generation unit may change a reduction ratio of the current picture and the reference picture according to the number of pixels that constitute the current picture. Accordingly, for example, by raising the reduction ratio as the number of pixels constituting a current picture to be coded increases, and by lowering the reduction ratio as the number of pixels decreases, the amount of calculation for estimating motion vectors can be controlled. In addition, by controlling the reduction ratio, it is also possible to realize, for an input video sequence having plural picture sizes and plural frame rate, the best estimation processing for the calculation capability of the motion vector estimation apparatus.

The above-mentioned motion vector estimation apparatus may further include a block size determination unit which estimates motion vectors of the current block in the region image using the candidate block sizes in descending order of size, in the case where at least one of the following conditions is satisfied: the region motion vector estimated by the region motion vector estimation unit is equal to or less than the first threshold value; and the confidence level of the region motion vector calculated by the confidence level calculation unit is equal to or less than the second threshold value, and when a motion vector estimated using one of the candidate block sizes becomes greater than a predetermined threshold value, determines the candidate block size as the block size to be used for coding the current block.

Furthermore, the motion vector estimation apparatus may further include a block size determination unit which estimates motion vectors of the current block using, in descending order of size, the candidate block sizes to which the candidate block sizes have been narrowed down, and when a motion vector estimated using one of the candidate block sizes becomes greater than a predetermined threshold value, determines the candidate block size as the block size to be used for coding the current block.

Accordingly, since the block size to be used for coding is determined when the conditions are satisfied, processing for determining the optimal block size can be simplified. Therefore, it is possible to reduce an amount of calculation and power required for estimating motion vectors.

Note that it is possible to embody the present invention not only as such a motion vector estimation apparatus, but also as a motion vector estimation method including, as steps, the characteristic units of the motion vector estimation apparatus, as well as a program for causing a computer to execute these steps. Furthermore, such a program can be distributed through a recording medium such as a CD-ROM and over a transmission medium such as the Internet.

As further information about technical background to this application, the disclosure of Japanese Patent Application No. 2005-241700 filed on Aug. 23, 2005 including specification, drawings and claims is incorporated herein by reference in its entirety.

DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

FIG. 2is a block diagram showing a structure of a video coding apparatus including a motion vector estimation apparatus according to the first embodiment of the present invention.

A video coding apparatus100is an apparatus for coding an input video sequence on a block-by-block basis, and includes, as shown inFIG. 2, a reduced picture generation unit1, a picture memory2, a region partition unit3, a region motion vector estimation unit4, a confidence level calculation unit5, a block size narrowing-down unit6and a coding unit7.

The reduced picture generation unit1receives a current picture to be coded including a current block to be coded, as well as a reference picture which is referred to for estimation of a motion vector used for coding the current block, performs calculation for reducing the number of pixels of the current picture to generate a reduced current picture to be coded, and performs calculation for reducing the number of pixels of the reference picture to generate a reduced reference picture. Here, a reduced picture is a picture which is reduced in size while maintaining the properties of the images included in the picture.

The reduced reference pictures generated by the reduced picture generation unit1are stored into the picture memory2.

The region partition unit3partitions the reduced current picture generated by the reduced picture generation unit1into a number of regions, and generates reduced region images.

The region motion vector estimation unit4estimates a region motion vector of each reduced region image generated by the region partition unit3, based on the pixel data which is present in a search region in the reduced reference picture generated by the reduced picture generation unit1.

A predicted reduced region image is generated from the reduced reference picture generated by the reduced picture generation unit1and the region motion vector estimated by the region motion vector estimation unit4. Then, the confidence level calculation unit5calculates the confidence level of each region motion vector, based on the predicted reduced region image and the reduced region image generated by the region partition unit3.

The block size narrowing-down unit6narrows down the candidate block sizes based on each region motion vector estimated by the region motion vector estimation unit4and the confidence level of each region motion vector calculated by the confidence level calculation unit5.

FIG. 3is a block diagram showing the structure of the coding unit7of the video coding apparatus100.

The coding unit7includes an intra-picture prediction unit701, a motion vector estimation unit702, a motion compensation unit703, a difference calculation unit704, an orthogonal transform unit705, a quantization unit706, an inverse quantization unit707, an inverse orthogonal transform unit708, an addition unit709, a picture memory710, a switch711and a variable length coding unit712.

The input picture is inputted to the intra-picture prediction unit701, the motion vector estimation unit702and the difference calculation unit704. The motion vector estimation unit702searches a decoded picture stored in the picture memory710, per region of each candidate block size to which the candidate block sizes have been narrowed down by the block size narrowing-down unit6, finds an image region which is most similar to the input picture from among the regions so as to determine the motion vector indicating the location of the most similar image region, and determines the block size having the smallest difference as a block size to be used for coding, as well as the motion vector of the block of that size. The motion compensation unit703extracts the optimal image region for prediction, as a predicted picture, from the decoded pictures stored in the picture memory710, using the motion vectors estimated by the motion vector estimation unit702so as to generate a predicted picture. The intra-picture prediction unit701performs intra-picture prediction using the coded pixels within the same picture so as to generate a predicted picture. The switch711switches between intra-picture prediction and inter-picture prediction.

On the other hand, when receiving the input picture, the difference calculation unit704calculates the difference value between the input picture and the predicted picture, and outputs this difference value to the orthogonal transform unit705. The orthogonal transform unit705transforms the difference value into frequency coefficients and outputs the resulting coefficients to the quantization unit706. The quantization unit706quantizes the inputted frequency coefficients and outputs the resulting quantized values to the variable length coding unit712.

The inverse quantization unit707inversely quantizes the inputted quantized values so as to reconstruct them to frequency coefficients, and outputs the resulting coefficients to the inverse orthogonal transform unit708. The inverse orthogonal transform unit708inversely frequency transforms the frequency coefficients into differential pixel values, and outputs the resulting values to the addition unit709. The addition unit709adds the differential pixel values to the pixel values of the predicted picture outputted from the intra-picture prediction unit701or the motion compensation unit703so as to obtain a decoded picture. The variable length coding unit111performs variable length coding of the quantized values, the motion vectors and the like, and outputs a stream.

Next, the operations of the video coding apparatus100including the motion vector estimation apparatus structured as mentioned above will be described.

FIG. 4is a flowchart showing the operation sequence when a motion vector is estimated.

First, the reduced picture generation unit1receives a current picture to be coded. The current picture to be coded consists of, for example, 1920×1080 pixels. The current picture includes a current block to be coded. The current block to be coded consists of, for example, 16×16 pixels.

The reduced picture generation unit1receives a reference picture which has been locally decoded by the coding unit7. The locally-decoded reference picture consists of, for example, 1920×1080 pixels. The reduced picture generation unit1is equipped with a filter which attenuates vertical or horizontal high frequency components of the current picture to be coded and the locally-decoded reference picture. The reduced picture generation unit1reduces the number of pixels that constitute the current picture and the reference picture which have been attenuated in their high frequency components by the filter, and generates a reduced current picture to be coded and a reduced reference picture (Step S101). Then, the reduced reference picture generated by the reduced picture generation unit1is stored into the picture memory2.

Next, the region partition unit3partitions the reduced current picture generated by the reduced picture generation unit1into a number of (four in the case ofFIG. 5B) regions of a predetermined size as shown inFIG. 5B, and generates reduced region images (Step S102). Note that a reduced current picture may be partitioned into regions of a fixed size, or may be partitioned into regions of various sizes determined based on the information such as the motion vectors of its reference picture or immediately preceding picture.FIG. 6AandFIG. 6Bare schematic diagrams showing the examples of how to partition a reduced current picture into regions based on the motion vectors of its reference picture or immediately preceding picture. Here, FIG.6A(a) and FIG.6B(c) each show motion vectors of respective macroblocks in a reference picture or an immediately preceding picture, while FIG.6A(b) and FIG.6B(d) each show determined region partition in a reduced current picture to be coded. For example, the region partition of the reduced current picture is determined so that each region corresponds to a group of combined adjacent macroblocks having motion vectors which point in the similar directions within a predetermined range. To be more specific, in the case where respective macroblocks in the reference picture or the immediately preceding picture have the motion vectors as shown in FIG.6A(a), the region partition of the reduced current picture is determined, as shown in FIG.6A(b), so as to have three regions51,52and53. In the case where respective macroblocks in the reference picture or the immediately preceding picture have the motion vectors as shown in FIG.6B(c), the region partition of the reduced current picture is determined, as shown in FIG.6B(d), so as to have only one region54. Note that as shown inFIG. 6B, a reduced current picture may be partitioned into one region.

Next, the region motion vector estimation unit4searches each region of the reduced reference picture, as shown in, for example,FIG. 5A, generated by the reduced picture generation unit1, finds the image region (for example, a image region42as shown inFIG. 5B) which is most similar to the reduced region image (for example, a reduced region image41as shown inFIG. 5B) from among the search regions, and determines the motion vector (for example, a motion vector43as shown inFIG. 5B) indicating the location of that image region so as to determine the region motion vector (Step S103). Here, the image region which is most similar to the reduced region image is, for example, an image region having the smallest sum of absolute differences (SAD), from among the SADs between pixel values of respective image regions in the search regions included in a reduced reference picture and pixel values of the reduced region image.

Next, the confidence level calculation unit5calculates the confidence level between each reduced region image included in the reduced reference picture detected by the region motion vector estimation unit4and the image region which is most similar to the reduced region image, and determines this level to be the confidence level of each region motion vector (Step S103). Note that this confidence level may be calculated based on the sum of absolute differences, or the variance or covariance.

Next, the block size narrowing-down unit6judges whether or not each region motion vector estimated by the region motion vector estimation unit4is greater than a predetermined threshold value and each confidence level of the region motion vector calculated by the confidence level calculation unit5is higher than a predetermined threshold value (Step S104). As a result, when the region motion vector is greater than the predetermined threshold value and the confidence level of the region motion vector is higher than the predetermined value (Yes in Step S104), the block size narrowing-down unit6narrows down the candidate block sizes to the largest size (Step S105). On the contrary, when the region motion vector is not greater than the predetermined threshold value or the confidence level of the region motion vector is not higher than the predetermined value (No in Step S104), the block size narrowing-down unit6does not narrow down the candidate block sizes for coding. As for candidate block sizes for coding, all the sizes defined in H.264/MPEG-4 AVC can be the candidates. Or, candidate block sizes may be changed depending on the number of pixels constituting a current picture to be coded. For example, if an input picture consists of 1920×1080 pixels as shown inFIG. 7A, blocks of 16×16, 16×8 and 8×16 can be the candidates. And if an input picture consists of 320×240 pixels as shown inFIG. 7B, blocks of 8×8, 8×4 and 4×8 pixels can be the candidates.

Next, the motion vector estimation unit702of the coding unit7estimates a motion vector, per block of the largest size to which the candidate block sizes have been narrowed down by the block size narrowing-down unit6, included in a current block to be coded within the region of the current picture corresponding to the reduced region image (Step S106). Note that in the present embodiment, the block size narrowing-down unit6narrows down the candidate block sizes to the largest size, but the present invention is not limited to this narrowing-down. For example, the block size narrowing-down unit6may narrow down the candidate block sizes to the largest and second largest sizes. In this case, the motion vector estimation unit702can estimate a motion vector, for each of the blocks of all the narrowed-down sizes, included in a current block to be coded within the region of the current picture corresponding to the reduced region image, and selects the most efficient block size from among them so as to estimate the motion vector of the block of that size.

After that, the coding unit7performs a series of processes such as motion compensation, orthogonal transform, quantization, variable length coding and the like, using the estimated motion vectors.

As described above, in the present embodiment, candidate block sizes are narrowed down for coding based on the region motion vectors estimated by the region motion vector estimation unit4and the confidence levels of the region motion vectors calculated by the confidence level calculation unit5. And, since the narrowing-down of block sizes eventually leads to determination of a block size to be used for coding, processing for determining the optimal block size can be omitted. Therefore, it is possible to reduce an amount of calculation and power required for estimating motion vectors.

By choosing which block size will be used for the most efficient coding, from among a number of block sizes, it is possible to reduce image degradation such as mosquito noise. However, since the use of smaller blocks increases information such as motion vectors, the number of bits for coding also increases. According to the motion vector estimation apparatus of the present embodiment, since the largest block size is selected from among candidate block sizes by exploiting the property that image degradation such as a block noise in a scene where there is a large amount of motion between pictures is less noticeable to human eyes than that in a static scene, it is possible to reduce the number of bits required for coding while minimizing visual image degradation.

Since the filter equipped in the reduced picture generation unit1attenuates the vertical or horizontal high frequency components of a current picture to be coded and a reference picture, it is possible not only to reduce the effect of noise when motion vectors are estimated but also to reduce the effect of aliasing when the number of pixels decreases by picture reduction. Therefore, the accuracy of motion vector estimation can be enhanced.

Note that the reduced picture generation unit1may change the reduction ratio of a current picture to be coded and a reference picture depending on the number of pixels constituting the current picture. For example, by raising the reduction ratio as the number of pixels constituting a current picture to be coded increases, and by lowering the reduction ratio as the number of pixels decreases, the amount of calculation for estimating motion vectors can be controlled. By controlling the reduction ratio, it is also possible to realize, for an input video sequence including plural pictures of different sizes or different frame rates, the best estimation processing for the calculation capability of the motion vector estimation apparatus.

In the first embodiment, the region motion vector estimation unit4estimates each region motion vector of a reduced region image using a reduced reference picture generated by the reduced picture generation unit1, but the present invention is not limited to such estimation. For example, the region motion vector may be the mean value of the motion vectors of the regions of the reference picture, each corresponding to each reduced region image.

The first embodiment shows an example where the region motion vector estimation unit4uses a reference picture which has been locally decoded by the coding unit7, but the present invention is not limited to such a case. For example, as shown inFIG. 8, the region motion vector estimation unit4may estimate region motion vectors based on a reduced reference picture obtained by reducing the size of an input picture.

As described above, the motion vector estimation apparatus of the present invention narrows down the candidate block sizes to be used for motion vector estimation based on the region motion vectors of regions in a picture and their confidence levels, and the processes for estimating motion vectors are reduced. Therefore, motion vector estimation can be speeded up.

FIG. 9is a block diagram showing a structure of a video coding apparatus including a motion vector estimation apparatus according to the second embodiment of the present invention. Note that the same reference numbers are assigned to the same constituent elements as those of the video coding apparatus100in the first embodiment as described with reference toFIG. 2. Therefore, a detailed description of these constituent elements is not repeated here.

A video coding apparatus300includes a block size determination unit301and a picture memory302as shown in FIG.9, in addition to the constituent elements of the video coding apparatus100.

In the case where as a result of the judgment of the block size narrowing-down unit6whether or not each region motion vector is greater than the predetermined threshold value and the confidence level of the region motion vector is higher than the predetermined threshold value, no region motion vector satisfy these conditions, the block size determination unit301estimates motion vectors using the candidate block sizes in descending order of size, and if a motion vector estimated in a block size is greater than a predetermined threshold value, the block size determination unit301determines this block size as a block size to be used for coding.

Next, the operations of the video coding apparatus300including the motion vector estimation apparatus structured as mentioned above will be described.

FIG. 10is a flowchart showing the operation sequence when a motion vector is estimated. Note that since the operation sequence from generation of a reduced current picture to be coded and a reduced reference picture (Step S101) up to narrowing-down of candidate block sizes by the block size narrowing-down unit6(Step S105) is same as that of the above first embodiment, a description thereof is not repeated here.

When the region motion vector is not greater than the predetermined threshold value or the confidence level of the region motion vector is not higher than the predetermined value (No in Step S104) as a result of the judgment by the block size narrowing-down unit6(Step S104), the block size determination unit301estimates a motion vector of the block of the largest size among the candidate block sizes (Step S201). Then, the block size determination unit301judges whether or not the estimated motion vector is greater than a predetermined threshold value and the confidence level of the motion vector is higher than a predetermined threshold value (Step S202). As a result, when the motion vector is greater than the predetermined threshold value and the confidence level of the motion vector is higher than the predetermined value (Yes in Step S202), the block size determination unit301determines the largest size among the candidate block sizes, as a block size to be used for coding (Step S203).

On the other hand, when the motion vector is not greater than the predetermined threshold value or the confidence level of the motion vector is not higher than the predetermined value (No in Step S202), the block size determination unit301estimates a motion vector of the block of the second largest size among the candidate block sizes (Step S204). Then, the block size determination unit301judges whether or not the estimated motion vector is greater than a predetermined threshold value and the confidence level of the motion vector is higher than a predetermined threshold value (Step S205). As a result, when the motion vector is greater than the predetermined threshold value and the confidence level of the motion vector is higher than the predetermined value (Yes in Step S205), the block size determination unit301determines the block size of the highest confidence level, among the largest and second largest block sizes, as a block size to be used for coding (Step S206). When the motion vector is not greater than the predetermined threshold value or the confidence level of the motion vector is not higher than the predetermined value (No in Step S205), the block size determination unit301estimates a motion vector of the block of the third largest size among the candidate block sizes, and in this way, the block size determination unit301estimates motion vectors in sequence.

Next, the motion vector estimation unit702of the coding unit7estimates motion vectors using the block size to which the candidate block sizes have been narrowed down by the block size narrowing-down unit6, namely the largest block size, or the block size determined by the block size determination unit301(Step S207). Note that when the region motion vector is not greater than the predetermined threshold value or the confidence level of the region motion vector is not higher than the predetermined value (No in Step S104) as a result of the judgment by the block size narrowing-down unit6(Step S104), the motion vector estimation unit702does not need to estimate a motion vector again because the block size determination unit301has estimated the motion vector.

After that, the coding unit7performs a series of processes such as motion compensation, orthogonal transform, quantization, variable length coding and the like, using the estimated motion vectors.

As described above, in the present embodiment, the block size determination unit301estimates in sequence motion vectors using candidate block sizes for coding in descending order of size, and determines the block size when the motion vector satisfies the above conditions. Therefore, processing for determining the optimal block size can be simplified. Therefore, it is possible to reduce an amount of calculation and power required for estimating motion vectors.

Note that in the case where two or more estimated motion vectors of blocks of same size and different shapes are greater than the predetermined threshold value, the block size of, for example, the highest confidence level among the confidence levels used for obtaining the motion vectors, is determined to be the block size to be used for coding a current block.

It is also possible for the block size determination unit301to perform the above-mentioned processing on a reduced number of candidate block sizes to which the candidate block sizes have been narrowed down by the block size narrowing-down unit6so as to determine a block size to be used for coding.

Each of the above embodiments can be applied to either luma components or chroma components of pixel data of a current picture to be coded.

Each functional block in the block diagrams shown inFIG. 2,FIG. 8andFIG. 9is realized as an LSI which is typically an integrated circuit. This LSI can be integrated into one chip, or also can be integrated into plural chips. For example, functional blocks other than a memory may be integrated into one chip. The name used here is LSI, but it may also be called IC, system LSI, super LSI, or ultra LSI depending on the degree of integration.

Moreover, ways to achieve integration are not limited to the LSI, and a special circuit or a general purpose processor and so forth can also achieve the integration. Field Programmable Gate Array (FPGA) that can be programmed after manufacturing LSI or a reconfigurable processor that allows reconfiguration of the connection or setup of circuit cells inside the LSI can be used for the same purpose.

In the future, with advancement in semiconductor technology or another technology derived therefrom, a brand-new integration technology may replace LSI. The integration can be carried out by that technology. Application of biotechnology is one such possibility.

Only a unit for storing data out of the functional blocks may be structured as a separate unit, not integrated into one chip.

INDUSTRIAL APPLICABILITY

Since the above-described motion vector estimation apparatus according to the present invention allows video coding in H.264 format with less calculation processing load, it can be applied not only to a personal computer, an HDD recorder and a DVD recorder but also to a video camera, a camera cellular phone and so forth. The present invention can also be applied to a coding apparatus equipped with this motion vector estimation apparatus.