Patent ID: 8457210
Filing Date: 2013-06-04
Classification: H04N

Abstract:
1. An image decoding apparatus comprising: an entropy decoder configured to restore a quantization discrete cosine transformation coefficient by performing entropy decoding of an image, which is encoded by dividing the image into rectangular areas, each comprising a predetermined number of pixels, and successively subjecting each of the rectangular areas of the image to two-dimensional discrete cosine transformation and quantization; an inverse quantization module configured to perform inverse quantization for a result of the decoding; an estimation module configured to perform linear estimation of a correction value of a discrete cosine transformation coefficient to be processed, for an inverse quantization result, based on discrete cosine transformation coefficient of a rectangular area including pixels to be processed and discrete cosine transformation coefficient of an area adjacent to the rectangular area including the pixels to be processed, when the discrete cosine transformation coefficient of the rectangular area including the pixels to be processed is zero, and to perform linear estimation of the correction value of the coefficient for the inverse quantization result, by adding a positive or negative sign of the coefficient before being corrected to a linear estimation result of an absolute value of the correction value of the coefficient, based on the discrete cosine transformation coefficient of the rectangular area including the pixels to be processed and discrete cosine transformation coefficient of the area adjacent to the rectangular area including the pixels to be processed, when the discrete cosine transformation coefficient of a rectangular area including the pixels to be processed is not zero; an estimation coefficient value limiting module configured to limit the correction value such that the correction value estimated by the estimation module falls within a predetermined range based on a quantization step; and an inverse discrete cosine transformation module configured to perform two-dimensional inverse discrete cosine transformation for a processing result obtained by the estimation coefficient value limiting module.