Abstract: Entropy encoding and entropy decoding of image data are respectively performed whereby context modeling is performed on a context unit of blocks of the image data based on a context model of a previously encoded or decoded block.

Abstract: Provided is a multilayer picture encoding/decoding apparatus and method for reducing a dynamic range of residual pictures occurring in enhancement layers. The multilayer picture encoding method includes performing format down-conversion on an input picture, and generating a lower layer bitstream by encoding the format down-converted input picture; performing format up-conversion by adaptively or selectively applying a 1-dimensional (1-D) prediction filter to a picture of the lower layer depending on whether a lower layer prediction flag is set or not; and calculating a residual picture between the input picture and the format up-converted picture, and generating an enhancement bitstream by encoding the calculated residual picture.

Abstract: Provided are an image encoding apparatus and an image decoding apparatus. The image encoding apparatus includes a compression unit compressing a reference image by reducing a resolution of the reference image in a resolution adjustment mode determined from among at least two resolution adjustment modes according to a distribution of values of pixels of the reference image, and providing the compressed reference image to a memory, a reconstruction unit reconstructing the reference image by increasing a resolution of the compressed reference image stored in the memory to an original resolution, a predictive encoding unit performing predictive encoding on a current image by using the reconstructed reference image, and a predictive decoding unit generating the reference image by performing decoding on the predictive encoded current image, and providing the generated reference image to the compression unit.

Abstract: An apparatus for encoding or decoding an image by storing and managing a reference frame used to encode or decode an encoding target image frame. To encode image frames classified into a plurality of layers, the apparatus may include a layer identification unit identifying a layer that includes a first encoding target frame, a frame storage unit storing at least one storage frame associated with the first encoding target frame, a reference frame selector selecting a reference frame from the at least one storage frame, based on the identified layer, and a frame encoder encoding the first encoding target frame by referring to the selected reference frame, wherein the frame storage unit stores the first encoding target frame as a storage frame associated with a second encoding target frame.

Abstract: Provided are an apparatus for encoding an image and an apparatus for decoding an image. The apparatus for encoding the image includes a grouping unit to group transform coefficients according to layers and generate groups, a pattern encoding unit to generate and encode the pattern information of each group by using the quantized transform coefficients existing in the groups of each layer in an order from an upper layer to a lower layer, and a level encoding unit to encode levels of the quantized transform coefficients corresponding to the pattern information of the groups of each layer and generate bitstreams along with the pattern information of the groups of each layer.

Abstract: Provided are an image encoding apparatus and an image decoding apparatus. The image encoding apparatus includes a compression unit compressing a reference image by reducing a resolution of the reference image in a resolution adjustment mode determined from among at least two resolution adjustment modes according to a distribution of values of pixels of the reference image, and providing the compressed reference image to a memory, a reconstruction unit reconstructing the reference image by increasing a resolution of the compressed reference image stored in the memory to an original resolution, a predictive encoding unit performing predictive encoding on a current image by using the reconstructed reference image, and a predictive decoding unit generating the reference image by performing decoding on the predictive encoded current image, and providing the generated reference image to the compression unit.

Abstract: A method, medium, and apparatus for encoding and/or decoding video by generating a scalable bitstream formed with a base layer bitstream and an enhancement layer bitstream in order to provide forward compatibility, the scalable bitstream comprising a base layer bitstream including a base quantized level and a base quantization parameter corresponding to a base bit-depth, and an enhancement layer bitstream including a residue between an extended quantized level and a compensated quantized level that is predicted from the base quantized level, and additional quantization information for refining the difference between an extended bit-depth and the base bit-depth, wherein a process for improving image quality is applied to at least one of the base layer and the enhancement layer.

Abstract: A method, medium, and apparatus for encoding and/or decoding video by generating a scalable bitstream compatible with at least two video formats generating an enhancement layer identifier, generating a base layer bitstream by encoding a chrominance component of a low-frequency band and a luminance component that are included in video, and generating an enhancement layer bitstream by encoding a chrominance component of the remaining frequency band other than the low-frequency band that is included in the video.