Abstract: Provided are method and apparatus for inverse quantizing an image, the method including: determining a quantization step correction value for reducing a quantization error, which is a difference between an inverse quantization coefficient, obtained by inverse quantizing a quantization coefficient, and an original value of the transformation coefficient; and inverse quantizing the quantization coefficient using a second quantization step value, the second quantization step value being obtained by correcting a first quantization step value used for inverse quantizing the quantization coefficient using the determined quantization step correction value.

Abstract: Provided are a method and apparatus for correcting quantized coefficients. In the method, statistical values of coefficients and quantized coefficients are extracted from a received video data stream, coefficient correction values for each pixel position in blocks are determined by using the statistical distribution of the coefficients depending on the statistical values, and then the coefficients are corrected by respectively adding the coefficient correction values to corresponding coefficients of respective pixel positions.

Abstract: A method and apparatus for coding an image by using exponential Golomb binarization are provided. The method comprises: performing entropy coding on an input image by performing exponential Golomb binarization using a plurality of predetermined thresholds; measuring a bit rate of a bit stream which is generated by performing the entropy coding using each threshold; and determining an optimal threshold by comparing bit rates with regard to the thresholds.

Abstract: A method of compressing image signals, to provide more efficient compression than a discrete cosine transform (DCT) while having the least amount of overhead information is provided. A partial exchange between a row and a column of a transform matrix is performed by applying several values to a parameter, which shows an extent of partial exchange between rows and columns of the transform matrix. When a value of the used angle parameter is stored or transmitted, an overhead increases. Processes generating a random sequence of the angle parameter, generating a compression coefficient matrix regarding each angle parameter of the generated random sequence, and calculating a compression rate are repeated to obtain an angle parameter with the highest compression rate. The angle parameter having the highest compression rate is not stored or transmitted, but a number in the random sequence of the corresponding angle parameter is obtained, and stored or transmitted.

Abstract: Provided are method and apparatus for inverse quantizing an image, the method including: determining a quantization step correction value for reducing a quantization error, which is a difference between an inverse quantization coefficient, obtained by inverse quantizing a quantization coefficient, and an original value of the transformation coefficient; and inverse quantizing the quantization coefficient using a second quantization step value, the second quantization step value being obtained by correcting a first quantization step value used for inverse quantizing the quantization coefficient using the determined quantization step correction value.

Abstract: A method of compressing image signals, to provide more efficient compression than a discrete cosine transform (DCT) while having the least amount of overhead information is provided. A partial exchange between a row and a column of a transform matrix is performed by applying several values to a parameter, which shows an extent of partial exchange between rows and columns of the transform matrix. When a value of the used angle parameter is stored or transmitted, an overhead increases. Processes generating a random sequence of the angle parameter, generating a compression coefficient matrix regarding each angle parameter of the generated random sequence, and calculating a compression rate are repeated to obtain an angle parameter with the highest compression rate. The angle parameter having the highest compression rate is not stored or transmitted, but a number in the random sequence of the corresponding angle parameter is obtained, and stored or transmitted.

Abstract: A method and apparatus for coding an image by using exponential Golomb binarization are provided. The method comprises: performing entropy coding on an input image by performing exponential Golomb binarization using a plurality of predetermined thresholds; measuring a bit rate of a bit stream which is generated by performing the entropy coding using each threshold; and determining an optimal threshold by comparing bit rates with regard to the thresholds.

Abstract: Provided are a method and apparatus for correcting quantized coefficients. In the method, statistical values of coefficients and quantized coefficients are extracted from a received video data stream, coefficient correction values for each pixel position in blocks are determined by using the statistical distribution of the coefficients depending on the statistical values, and then the coefficients are corrected by respectively adding the coefficient correction values to corresponding coefficients of respective pixel positions.