Abstract: A method of simplifying the arithmetic operation in a global motion compensation process approximates the motion vector field of the whole image without using many parameters. Motion vectors in the global motion compensation are found by the interpolation and/or extrapolation of the motion vectors of a plurality of representative points 602, 603 and 604 having particular features in the spatial distance thereof. Since the shift operation can be substituted for the division for synthesizing a predicted image of global motion compensation, the processing using a computer or a dedicated hardware is simplified.

Abstract: An image decoder includes a memory which stores a reference image which is a previously decoded image, and a synthesizer which receives motion vector information and rounding method information specifying a rounding method used in synthesizing a prediction image, and synthesizes a prediction image by performing motion compensation using the motion vector information and the reference image. The synthesizer performs either a positive rounding method or a negative rounding method for interpolating intensity values of pixels in performing the motion compensation according to the rounding method information, but enables performance of both the positive rounding method and the negative rounding method for interpolating intensity values of pixels in performing the motion compensation. The rounding method information specifies either the positive rounding method or the negative rounding method.

Abstract: A recording medium has recorded thereon information related to coded data of an image sequence, which is a set of coded frame information of a plurality of frames of an image sequence. The coded frame information includes information related to a difference image between an image of a current frame and a prediction image of the current frame, the prediction image being synthesized by performing motion compensation, information related to motion vectors estimated in performing the motion compensation, and rounding method information specifying a rounding method used in performing the motion compensation. The rounding method specified by the rounding method information is used for pixel value interpolation in performing the motion compensation, and specifies one of a positive rounding method and a negative rounding method.

Abstract: An image coding method includes the steps of synthesizing a prediction image by performing motion compensation, and multiplexing information related to a difference image between an input image and the prediction image, and information related to motion vectors estimated in performing the motion compensation. The motion compensation is sometimes performed using a positive rounding method, and is sometimes performed using a negative rounding method. Information related to a rounding method used in performing the motion compensation is multiplexed with the information related to the difference image and the information related to the motion vectors.

Abstract: A computer-readable medium having stored thereon an image decoding program which, when executed by a computer, performs the steps of extracting motion vector information and quantized DCT coefficients from input information to be decoded, synthesizing a prediction image by performing motion compensation using the motion vector information and a reference image which is a previously decoded image, synthesizing a decoded image by adding the prediction image to an error image obtained by applying dequantization and inverse DCT conversion to the quantized DCT coefficients. The motion compensation is performable using a positive rounding method and a negative rounding method for interpolating intensity values of pixels in performing the motion compensation.

Abstract: A computer-readable medium having stored thereon an image decoding program which, when executed by a computer, performs the steps of storing a reference image which is a previously decoded image, receiving information including motion vector information and rounding method information specifying a rounding method used in synthesizing a prediction image, and synthesizing a prediction image by performing motion compensation using the motion vector information and the reference image. The step of synthesizing a prediction image includes the step of performing either a positive rounding method or a negative rounding method for interpolating intensity values of pixels in performing the motion compensation according to the rounding method information, but enables performance of both the positive rounding method and the negative rounding method for interpolating intensity values of pixels in performing the motion compensation.

Abstract: A method and apparatus for coding an image includes calculation of motion vectors of vertices of a patch in an image being encoded and transmitting information of horizontal and vertical components of the motion vectors of the vertices and information specifying that values of the horizontal and vertical components of a motion vector for each pixel in the patch are integral multiples of 1/d of a distance between adjacent pixels, where d is an integer not less than 2.

Abstract: A method of decoding images includes the steps of extracting motion vector information and quantized DCT coefficients from input information to be decoded, synthesizing a prediction image by performing motion compensation using the motion vector information and a reference image which is a previously decoded image, and synthesizing a decoded image by adding the prediction image to an error image obtained by applying dequantization and inverse DCT conversion to the quantized DCT coefficients. The motion compensation is performable using a positive rounding method and a negative rounding method for interpolating intensity values of pixels in performing the motion compensation.

Abstract: An image decoder includes a demultiplexer which extracts motion vector information and quantized DCT coefficients from input information to be decoded, a dequantizer which dequantizes the quantized DCT coefficients to obtain DCT coefficients, an inverse DCT converter which performs inverse DCT conversion on the DCT coefficients to obtain an error image, a prediction image synthesizer which synthesizes a prediction image by performing motion compensation using the motion vector information and a reference image which is a previously decoded image, and an adder which adds the prediction image to the error image to obtain a decoded image. The motion compensation is performable using a positive rounding method and a negative rounding method for interpolating intensity values of pixels in performing the motion compensation.

Abstract: An image decoding method includes the steps of storing a reference image which is an image previously decoded based on a first prediction image synthesized by performing motion compensation, receiving motion vector information, and synthesizing a second prediction image by performing motion compensation using the motion vector information and the reference image. A rounding method used for pixel value interpolation in performing the motion compensation for synthesizing the second prediction image is different from a rounding method used for pixel value interpolation in performing the motion compensation for synthesizing the first prediction image. The rounding method used in synthesizing the first prediction image may be one of a positive rounding method and a negative rounding method, and the rounding method used in synthesizing the second prediction image may be a different one of the positive rounding method and the negative rounding method.

Abstract: A method and apparatus for coding an image includes calculation of motion vectors of vertices of a patch in an image being encoded and transmitting information of horizontal and vertical components of the motion vectors of the vertices and information specifying that values of the horizontal and vertical components of a motion vector for each pixel in the patch are integral multiples of 1/d of a distance between adjacent pixels, where d is an integer not less than 2.

Abstract: A method of simplifying the arithmetic operation in a global motion compensation process approximates the motion vector field of the whole image without using many parameters. Motion vectors in the global motion compensation are found by the interpolation and/or extrapolation of the motion vectors of a plurality of representative points 602, 603 and 604 having particular features in the spatial distance thereof. Since the shift operation can be substituted for the division for synthesizing a predicted image of global motion compensation, the processing using a computer or a dedicated hardware is simplified.

Abstract: An image coding method includes the steps of storing a reference image which is a decoded image of an image previously coded based on a first prediction image synthesized by performing motion compensation, estimating motion vectors based on a comparison of an input image to be coded and the reference image, and synthesizing a second prediction image by performing motion compensation using the motion vectors and the reference image. A rounding method used for pixel value interpolation in performing the motion compensation for synthesizing the first prediction image is one of a positive rounding method and a negative rounding method, and a rounding method used for pixel value interpolation in performing the motion compensation for synthesizing the second prediction image is a different one of the positive rounding method and the negative rounding method.

Abstract: A method and apparatus for simplifying an operation for the processing of a warping prediction of dividing an image into patches and deforming each patch by affine transform or bilinear transform. Motion vectors of a plurality of representative points in which a spatial interval has a special feature are obtained from at least one patch formed with a plurality of grid points. Information of the motion vectors are used for synthesis of a predicted image. The division for synthesizing a predicted image in the case of warping prediction is replaced with a shift operation, thereby simplifying the processing by a computer or exclusive hardware.

Abstract: A method of simplifying the arithmetic operation in a global motion compensation process approximates the motion vector field of the whole image without using many parameters. Motion vectors in the global motion compensation are found by the interpolation and/or extrapolation of the motion vectors of a plurality of representative points 602, 603 and 604 having particular features in the spatial distance thereof. Since the shift operation can be substituted for the division for synthesizing a predicted image of global motion compensation, the processing using a computer or a dedicated hardware is simplified.

Abstract: A method and apparatus for coding an image includes calculation of motion vectors of vertices of a patch in an image being encoded and providing an output of horizontal and vertical components of the motion vectors of the vertices and information specifying that values of the horizontal and vertical components of a motion vector for each pixel in the patch are integral multiples of 1/d of a distance between adjacent pixels, where d is an integer not less than 2.

Abstract: A method and apparatus for simplifying an operation for the processing of a warping prediction of dividing an image into patches and deforming each patch by affine transform or bilinear transform. Motion vectors of a plurality of representative points in which a spatial interval has a special feature are obtained from at least one patch formed with a plurality of grid points. Information of the motion vectors are used for synthesis of a predicted image. The division for synthesizing a predicted image in the case of warping prediction is replaced with a shift operation, thereby simplifying the processing by a computer or exclusive hardware.

Abstract: A method of simplifying the arithmetic operation in a global motion compensation process approximates the motion vector field of the whole image without using many parameters. Motion vectors in the global motion compensation are found by the interpolation and/or extrapolation of the motion vectors of a plurality of representative points 602, 603 and 604 having particular features in the spatial distance thereof. Since the shift operation can be substituted for the division for synthesizing a predicted image of global motion compensation, the processing using a computer or a dedicated hardware is simplified.

Abstract: A method of simplifying the arithmetic operation in a global motion compensation process approximates the motion vector field of the whole image without using many parameters. Motion vectors in the global motion compensation are found by the interpolation and/or extrapolation of the motion vectors of a plurality of representative points 602, 603 and 604 having particular features in the spatial distance thereof. Since the shift operation can be substituted for the division for synthesizing a predicted image of global motion compensation, the processing using a computer or a dedicated hardware is simplified.

Abstract: A method and apparatus for coding an image includes calculation of motion vectors of vertices of a patch in an image being encoded and providing an output of horizontal and vertical components of the motion vectors of the vertices and information specifying that values of the horizontal and vertical components of a motion vector for each pixel in the patch are integral multiples of {fraction (1/d)} of a distance between adjacent pixels, where d is an integer not less than 2.