Abstract: An object-based coding apparatus and method for image signals, wherein upon scanning shape-adaptive transform coefficients of an input image signal transformed in accordance with a shape-adaptive transform, only segments containing such shape-adaptive transform coefficients are scanned. In the scanning operation, segments containing no transform coefficient are skipped, thereby reducing the quantity of data being encoded. An apparatus for and a method of object-based decoding of image signals are also disclosed which can decode bit streams generated using the coding method, thereby reproducing image signals.

Abstract: A predictive coding in a video coding system, which can enhance the coding efficiency by predictively coding DC coefficients of a block to be coded using DC gradients of a plurality of previously coded neighboring blocks. The predictive coefficient is selected according to the difference between the quantized DC gradients (coefficients) of a plurality of neighboring blocks of the block to be coded, and the DC coefficient of the block to be coded is predictively coded by the selected predictive coefficient, thereby enhancing the coding efficiency.

Abstract: The present invention selectively applies one of VLC tables stored in a memory for encoding a coded block pattern of a macroblock according to the number of blocks having an object within the macroblock, the number of blocks obtained using shape information, thereby reducing the amount of data transmitted and increasing coding efficiency. The present invention also selectively applies one of VLD tables stored in a memory for decoding a coded block pattern of a macroblock according to the number of blocks having an object within the macroblock, the number of blocks obtained using shape information.

Abstract: A transcoding method and apparatus for converting a digital bitstream complying with a certain compression method into a digital bitstream complying with a different (or the same) compression method is provided. The transcoding apparatus performs conversion between compressed bitstreams having at least syntax elements and video elements corresponding to video data.

Abstract: The present invention selectively applies one of VLC tables stored in a memory for encoding a coded block pattern of a macroblock according to the number of blocks having an object within the macroblock, the number of blocks obtained using shape information, thereby reducing the amount of data transmitted and increasing coding efficiency.

Abstract: The present invention selectively applies one of VLC tables stored in a memory for encoding a coded block pattern of a macroblock according to the number of blocks having an object within the macroblock, the number of blocks obtained using shape information, thereby reducing the amount of data transmitted and increasing coding efficiency. The present invention also selectively applies one of VLD tables stored in a memory for decoding a coded block pattern of a macroblock according to the number of blocks having an object within the macroblock, the number of blocks obtained using shape information.

Abstract: The present invention selectively applies one of VLC tables stored in a memory for encoding a coded block pattern of a macroblock according to the number of blocks having an object within the macroblock, the number of blocks obtained using shape information, thereby reducing the amount of data transmitted and increasing coding efficiency.

Abstract: All macro blocks (MB) decided as an “all_0”, “all_255” or “intra predicted” mode are transmitted as an “intra not coded” mode. A receiving terminal also separates “all_0”, “all_255” and “intra predicted” from the “intra not coded” mode, referring to pixels of a lower layer. “Inter coded && MVD=0” and “Inter coded && MVD!=0” modes are represented as “Inter coded”, and “Inter not coded && MVD=0” and “Inter not coded && MVD!=0” modes are represented as “Inter not coded”. As its result, coding modes on an I-picture can be reduced to two modes and coding modes on a P-picture, or a B-picture, can be lessened to four modes.

Abstract: The present invention selectively applies one of VLC tables stored in a memory for encoding a coded block pattern of a macroblock according to the number of blocks having an object within the macroblock, the number of blocks obtained using shape information, thereby reducing the amount of data transmitted and increasing coding efficiency. The present invention also selectively applies one of VLD tables stored in a memory for decoding a coded block pattern of a macroblock according to the number of blocks having an object within the macroblock, the number of blocks obtained using shape information.

Abstract: A transcoding method and apparatus for converting a digital bitstream complying with a certain compression method into a digital bitstream complying with a different (or the same) compression method is provided. The transcoding apparatus performs conversion between compressed bitstreams having at least syntax elements and video elements corresponding to video data.

Abstract: A method and system for contour-based motion estimation for use with video images. The invention establishes corresponding contours (404, 414) in two images (402, 412) in a sequence of images, determines a motion vector which includes how the first contour (404) moved to become the second contour (414), and transmits the motion vector of the contour (414) in order to permit accurate display of the second video image (412). Preferably, boundary lines are removed from the contours before a comparison is made. The invention is computationally efficient and economical from a data transmission point of view, while enabling the production of accurate image.

Abstract: All macro blocks (MB) decided as an “all_0”, “all_255” or “intra predicted” mode are transmitted as an “intra not coded” mode. A receiving terminal also separates “all_0”, “all_255” and “intra predicted” from the “intra not coded” mode, referring to pixels of a lower layer. “Inter coded && MVD=0” and “Inter coded && MVD!=0” modes are represented as “Inter coded”, and “Inter not coded && MVD=0” and “Inter not coded && MVD!=0” modes are represented as “Inter not coded”. As its result, coding modes on an I-picture can be reduced to two modes and coding modes on a P-picture, or a B-picture, can be lessened to four modes.

Abstract: A method and an apparatus for predictively coding shape information of a video signal. An error between the current shape information and the previous shape information is obtained through the comparison therebetween. If the obtained error is greater than or equal to a predetermined reference value, the current shape information is coded. However, in the case where the obtained error is smaller than the predetermined reference value, the current shape information is reconstructed using the previous shape information. Therefore, a time-axis redundancy of the shape information is removed to prevent the transmission of unnecessary information, resulting in an increase in compression coding efficiency.

Abstract: A predictive coding in a video coding system, which can enhance the coding efficiency by predictively coding DC coefficients of a block to be coded using DC gradients of a plurality of previously coded neighboring blocks. The predictive coefficient is selected according to the difference between the quantized DC gradients (coefficients) of a plurality of neighboring blocks of the block to be coded, and the DC coefficient of the block to be coded is predictively coded by the selected predictive coefficient, thereby enhancing the coding efficiency.

Abstract: A method selects a requantization step size which abruptly changes a bit-rate in a piecewise linearly decreasing model and controls the bit-rate.

Abstract: An image encoding method and apparatus for controlling a bit generation quantity using a quantization activity accurately controls a bit generation quantity of an encoding frame.

Abstract: A method and an apparatus for predictively coding a contour of a video signal. An error between the current contour and the previous contour is obtained through the comparison therebetween. If the obtained error is greater than or equal to a predetermined reference value, the current contour is coded. However, in the case where the obtained error is smaller than the predetermined reference value, only a signal indicative of the reconstruction of the current contour using the previous contour is transmitted to a decoder. Therefore, the transmission of unnecessary information is prevented to enhance the compression coding efficiency.

Abstract: A sequential polygon approximation apparatus for a contour and a method thereof which are capable of sequentially extracting a vertex in the order of a contour pixel when performing a polygon approximation so as to code a shape information, which includes an error computation unit for obtaining a contour pixel between two contour pixels of the vertex extraction unit from the contour pixel memory and computing an error which is a distance between a straight line between two contour pixels and a pixel from the contour pixel memory, a comparison unit for comparing an error obtained by the error computation unit with a threshold value, and a controller for controlling the vertex extraction unit and the error computation unit in accordance with the comparison result of the comparison unit, setting the pixel just before the final pixel of a first region as a first vertex when the error obtained in the first region which is the region of the contour pixel sequentially determined for the vertex extraction from a fixe

Abstract: A method for determining a coding type and a coding mode for object shape coding is disclosed. A coding mode is determined according to the characteristic of an object and shape, and the shape is coded by varying a coding method according to the determined coding mode.

Abstract: An improved grid moving method of an object image and an apparatus using the same which are capable of reducing the amount of information with respect to the image of an object by moving the grid in accordance with a position in which an image of the object having shape information exists, which include the steps of: a moving step for forming a grid over an image of an object having shape information, segmenting the image into a plurality of unit regions, and moving the formed grid; a judging step for judging an amount of the information at each position to which the grid is moved in the moving step; a detecting step for detecting a position at which the amount of the information is reduced; a compaction step for reforming the grid in accordance with the position detected in the detecting step and for coding the image of the object existing in unit regions of the reformed grid; and a motion estimation step for reforming the grid in accordance with the position detected in the detecting step and for estimating