Abstract: An image encoding method and apparatus, and an image decoding method and apparatus respectively corresponding to the image encoding method and apparatus are provided. The image encoding method includes: if a current block is an initial block of a current slice, determining whether a virtual block in which pixel values are equal to a predetermined value is identical to the current block; and encoding the current block in a first mode based on the determining, wherein the first mode is a mode for encoding information representing that the current block is encoded in the first mode, instead of encoding pixel values of the current block, when the current block is identical to the virtual block.

Abstract: A method and apparatus for decoding hierarchical mode information including mode information indicating whether a current block is encoded in an encoding mode identical to an encoding mode of a plurality of consecutive previous blocks.

Abstract: Provided are methods and apparatuses for encoding data. One method of encoding data includes generating second data by altering locations of bits within first data to be encoded next based on values of bits within at least one piece of previously encoded data; and entropy-encoding the second data. Also provided are methods and apparatuses for decoding data.

Abstract: A method and apparatus are provided for encoding and decoding an image which entropy encode and decode a residual value of a current pixel in consideration of a context model determined with reference to at least one pixel value that is encoded and decoded before the current pixel and distribution of the residual values encoded and decoded according to the determined context model.

Abstract: Provided is a method and apparatus for compression encoding/decoding an image based on the repetition of an access unit and the repetition of a residual value.

Abstract: A method and apparatus for encoding/decoding an image, wherein the method includes selecting a predetermined binarization table from a plurality of binarization tables based on prediction values of a current pixel and binarizing or inversely binarizing residual values by using the selected binarization table.

Abstract: Provided are method and apparatus for encoding and decoding an image by using a bit plane-based image encoding method and a block-based image encoding method respectively on bit planes based on the n-m most significant bits of an input image including n-bit pixel values and an image based on the m least significant bits of the input image.

Abstract: Provided are an image processing method and image processing apparatus using least significant bits (LSBs). The image processing method includes generating first binary codes by converting pixel values of an input image into a binary code format; converting the first binary codes into gray codes and determining a predetermined number of sequential LSBs from among the gray codes; and generating second binary codes by converting the determined LSBs of the gray codes into the binary code format.

Abstract: Provided are entropy encoding and decoding methods. The entropy encoding method includes receiving residual coefficients obtained by frequency converting a residual image, determining a first bit string about residual coefficients having nonzero levels from among the received residual coefficients, determining at least one lower bit, including a least significant bit of the first bit string, from the first bit string, and determining a second bit string obtained by bit-shifting the first bit string to the right by the number of lower bits.

Abstract: Provided are methods and apparatuses for converting a lower bit-plane image, and methods and apparatuses for inverse-converting the lower bit-plane image, which increase the correlation of the lower bit-plane image. According to the method of converting a lower bit-plane image, pixels of the lower bit-plane image are sequentially added or subtracted so as to generate a converted lower bit-plane image. Accordingly, the lower bit-plane image has higher regularity, and thus the efficiency of image processing using the lower bit-plane image is improved.

Abstract: Provided are a method and apparatus for encoding and decoding an image. The method of encoding an image includes generating half-tone data by applying patterns specified by each color channel to input data, rearranging the generated half-tone data according to the characteristics of the applied patterns, and predicting the rearranged half-tone data and encoding the predicted half-tone data. Therefore, encoding and decoding can be performed more efficiently and a compression rate can be improved.

Abstract: A method to encode and decode a halftone image such that the halftone image is efficiently compressed and decoded by using pattern characteristics of the halftone image includes determining different template shapes according to characteristics of the halftone image, compressing the halftone image based on determined template shape information, compressing the template shape information, and generating the compressed halftone image and the compressed template shape information as a bitstream.