Abstract: A method and apparatus for coding an image capable of performing a prediction coding process by using a correlation degree between neighboring pixels of a current block and neighboring pixels of a reference block, and an image decoding method and apparatus. In the method, reference block candidates having neighboring pixels similar to the neighboring pixels of the current block are selected, matching errors between selected reference block candidates and the current block are calculated, and a reference block candidate having the least matching error is determined to be a predicted block of the current block.

Abstract: Provided are a bit rate control method and apparatus for intra-only coding, the method including calculating a similarity between at least one block group from among block groups including a plurality of macroblocks in a current frame to be encoded and at least one block group in a previous frame, which corresponds to the at least one block group in the current frame, determining a target bit amount of a current block group including a current macroblock using a video characteristic of the previous frame if the calculated similarity is greater than a threshold value, determining a target bit amount of the current macroblock based on the determined target bit amount of the current block group, and calculating a quantization parameter of the current macroblock based on the determined target bit amount of the current macroblock and the amount of bits generated for up to a previous macroblock.

Abstract: Provided are an image encoding method and apparatus and an image decoding method and apparatus that are capable of canceling a correlation remaining in a residual image by predicting the residual image by using residual pixel values of restored neighboring pixels of a current block and then encoding only the difference between the residual image and a predicted image of the residual image, where the residual image is obtained using an inter color compensation algorithm that predicts one of a plurality of color component images constituting an image by using one of the remnants of the color component images.

Abstract: A bitrate control method and apparatus for video sequence coding by using only intra pictures are provided. The rate control method includes: separating a video sequence formed only with intra pictures, into picture group units, slice units, and macroblock units; and performing bitrate control so that a predetermined amount of bits can be generated when encoding is performed. According to the method and apparatus, overflow and underflow of a buffer can be prevented.

Abstract: Provided are methods and apparatuses for encoding and decoding an image. The method of encoding the image includes calculating the number of times that encoding information of each of a plurality of sub-blocks included in a current block is exactly predicted, determining whether or not to predictably encode the encoding information of each sub-block, based on the calculated number of times, and predictably encoding the encoding information of each sub-block according to the determination. Using the method can prevent the case in which many bits are required to encode the encoding information due to inexact prediction about the encoding information, thereby decreasing the compression ratio of the image encoding process, and can compress the image with a higher efficiency.

Abstract: A method and apparatus for coding an image capable of performing a prediction coding process by using a correlation degree between neighboring pixels of a current block and neighboring pixels of a reference block, and an image decoding method and apparatus. In the method, reference block candidates having neighboring pixels similar to the neighboring pixels of the current block are selected, matching errors between selected reference block candidates and the current block are calculated, and a reference block candidate having the least matching error is determined to be a predicted block of the current block.

Abstract: Provided are video encoding and decoding methods and apparatuses for encoding a video by variably selecting one from two or more difference color formats. Accordingly, by using at least one of channel state information and a result of encoding a video in a predetermined encoding unit encoded in advance, whether or not to convert a video in a current encoding unit of an input RGB (red, green, blue) color format into a YCbCr color format is adaptively determined to perform encoding. Therefore, a video with uniform quality corresponding to a channel environment having a variable bit-rate can be provided.

Abstract: Provided are a bit rate control method and apparatus for intra-only coding, the method including calculating a similarity between at least one block group from among block groups including a plurality of macroblocks in a current frame to be encoded and at least one block group in a previous frame, which corresponds to the at least one block group in the current frame, determining a target bit amount of a current block group including a current macroblock using a video characteristic of the previous frame if the calculated similarity is greater than a threshold value, determining a target bit amount of the current macroblock based on the determined target bit amount of the current block group, and calculating a quantization parameter of the current macroblock based on the determined target bit amount of the current macroblock and the amount of bits generated for up to a previous macroblock.

Abstract: A bitrate control method and apparatus for video sequence coding by using only intra pictures are provided. The rate control method includes: separating a video sequence formed only with intra pictures, into picture group units, slice units, and macroblock units; and performing bitrate control so that a predetermined amount of bits can be generated when encoding is performed. According to the method and apparatus, overflow and underflow of a buffer can be prevented.

Abstract: A method and apparatus for compensating for illumination of a reference block and a method and apparatus for encoding an image, using the illumination compensation method and apparatus, are provided. The method of compensating for illumination of a reference block includes: predicting the mean values of pixels of a current block and a reference block, based on restored values of pixels neighboring the current block, and restored values of pixels neighboring the reference block; and based on the predicted mean value of the pixels of the current block, the predicted mean value of the pixels of the reference block, and the values of the pixels of the current block and the reference block, determining an illumination compensation parameter.

Abstract: Provided are an image encoding method and apparatus and an image decoding method and apparatus that are capable of canceling a correlation remaining in a residual image by predicting the residual image by using residual pixel values of restored neighboring pixels of a current block and then encoding only the difference between the residual image and a predicted image of the residual image, where the residual image is obtained using an inter color compensation algorithm that predicts one of a plurality of color component images constituting an image by using one of the remnants of the color component images.