Hitachi, Ltd.

Renesas Technology Corp.

Yuichiro Nakaya

Junichi Kimura

Yoshinori Suzuki

Minoru Nagata

Masanori Maruyama

Yukio Fujii

Yoshito Nejime

A computer-readable medium having stored thereon an image decoding program which, when executed by a computer, implements operations including: extracting motion vector information, and rounding method information 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; wherein a rounding method used for pixel value interpolation in performing the motion compensation for synthesizing the prediction image is one of a positive rounding method and a negative rounding method which is different from a one of a positive rounding method and a negative rounding method used for pixel value interpolation in performing the motion compensation for synthesizing a last prediction image.

Recording medium having recorded thereon coded information using plus and/or minus rounding of images

Medium having image decoding program effecting: extracting motion vector information, quantized DCT coefficients, and rounding method information; dequantizing quantized DCT coefficients to DCT coefficients; performing inverse DCT conversion on the DCT coefficients to an error image; synthesizing a prediction image of a currently decoded image via motion compensation using motion vector information, rounding method information, and a previously-decoded reference image; and adding the prediction and error images to a decoded image; wherein motion compensation is performed with half-pixel accuracy and uses bilinear interpolation to calculate intensity values of chrominance or luminance where no pixels exist in the reference image, using a positive or negative rounding method; wherein interpolation is performed using a rounding method specified by one-bit rounding method information included in a header section of coded information of the current image; wherein the rounding method specifies one of two values specifying a positive or negative rounding method.

Medium having image decoding program effecting: extracting motion vector information, quantized DCT coefficients, and rounding method information from input information; dequantizing quantized DCT coefficients to DCT coefficients; performing inverse DCT conversion on the DCT coefficients to an error image; synthesizing a prediction image of a currently decoded image by performing motion compensation using motion vector information, rounding method information, and a previously decoded reference image; and adding the prediction and error images to obtain a decoded image; wherein motion compensation is performed with half-pixel accuracy using bilinear interpolation to calculate intensity values of chrominance or luminance at points where no pixels exist in the reference image, the interpolation being performable using a positive or negative rounding method, and using a rounding method specified by rounding method information included in coded information of the currently decoded image, in a header section of the coded information of the current image.

Medium having decoding program effecting: extracting motion vector information, quantized DCT coefficients, and rounding method information from input information to be decoded; dequantizing quantized DCT coefficients to obtain DCT coefficients; performing inverse DCT conversion on the DCT coefficients to obtain an error image; synthesizing a prediction image of a currently decoded image by performing motion compensation using motion vector information, rounding method information, and a previously decoded reference image; and adding the prediction image to the error image; wherein the motion compensation is performed with half-pixel accuracy and uses bilinear interpolation to calculate intensity values of chrominance or luminance at points where no pixels actually exist in the reference image, the bilinear interpolation being performable using a positive or negative rounding method; wherein bilinear interpolation is performed using a rounding method specified by rounding method information; and wherein the rounding method information is included, in the currently decoded image.

Medium with image decoding program effecting: extracting motion vector information, quantized DCT coefficients, and rounding method information from input information; dequantizing quantized DCT coefficients to obtain DCT coefficients; performing inverse DCT conversion on DCT coefficients to obtain an error image; synthesizing a prediction image of a currently decoded image by performing motion compensation using motion vector information, rounding method information, and previously decoded reference image; and adding prediction and error images to obtain a decoded image; performing motion compensation with half-pixel accuracy and uses bilinear interpolation to calculate intensity values of chrominance or luminance at points where no pixels exist in the reference image, the interpolation being performable using a positive or negative rounding method; wherein the interpolation uses a rounding method specified by rounding method information included in coded information of the currently decoded image; and wherein the rounding method information specifies one of a plurality of values.

Medium with image decoding program effecting: extracting motion vector information, quantized DCT coefficients, and rounding method information from input information; dequantizing quantized DCT coefficients to DCT coefficients; performing inverse DCT conversion to an error image; synthesizing a prediction image of a currently decoded image by performing motion compensation using motion vector information, rounding method information, and a previously decoded reference image; and adding prediction and error images to obtain a decoded image; wherein motion compensation is performed with half-pixel accuracy and uses bilinear interpolation to calculate intensity values of chrominance or luminance at points where no pixels exist in the reference image, the interpolation using a positive or negative rounding method, using rounding specified by rounding method information included in coded information of the currently decoded image; wherein the rounding method specifies one of two values specifying a positive or negative rounding method, via rounding method information of one bit.

Medium having image decoding program effecting: extracting motion vector information, quantized DCT coefficients, and rounding method information from input information; dequantizing quantized DCT coefficients to DCT coefficients; performing inverse DCT conversion on the DCT coefficients to an error image; synthesizing a prediction image of a currently decoded image by performing motion compensation using motion vector information, rounding method information, and a previously decoded reference image; and adding the prediction and error images to obtain a decoded image; wherein motion compensation is performed with half-pixel accuracy using bilinear interpolation to calculate intensity values of chrominance or luminance at points where no pixels exist in the reference image, the interpolation performable using a positive or negative rounding method, specified by rounding method information specifying one of plural values and included in coded information of the currently decoded image, in a header section of the coded information of the current image.

Growing community of inventors

Suginami-ku, Japan

Yuichiro Nakaya