Apparatus and method for coding/decoding image selectivly using descrete cosine/sine transtorm

Abstract

Disclosed is a data transmission system that transmits data by using a relay. The relay selects a transmission terminal from among a plurality of terminals accessing a base station. A base station transmits base station data to the relay during a first time slot, and the transmission terminal transmits terminal data to the relay. The relay transmits terminal data to the base station during a second time slot, and transmits base station data to the transmission terminal.

1 . An apparatus of coding an image, comprising:
 a first transforming unit to transform a target image into a first transform coefficient based on a discrete cosine transform (DCT) scheme;   a second transforming unit to transform the target image into a second transform coefficient based on a discrete sine transform (DST) scheme; and   a transform scheme determining unit to select one of the first transform coefficient and the second coefficient as a transform coefficient of the target image.   
     
     
         2 . The apparatus of  claim 1 , wherein:
 the first transforming unit generates a first decoded image of the target image based on the first transform coefficient;   the second transforming unit generates a first decoded image of the target image based on the second transform coefficient; and   the transform scheme determining unit compares the target image, the first decoded image, and the second decoded image, to select the transform coefficient.   
     
     
         3 . The apparatus of  claim 2 , further comprising:
 a Lagrange multiplier calculator to calculate a Lagrange multiplier based on a size of the target image,   wherein the transform scheme determining unit selects the transform coefficient based on the Lagrange multiplier.   
     
     
         4 . The apparatus of  claim 3 , further comprising:
 a rate-distortion cost calculator to measure a rate-distortion cost of the first decoded image with respect to the target image based on the calculated Lagrange multiplier, and to calculate a rate-distortion cost of the second decoded image with respect to the target image based on the calculated Lagrange multiplier,   wherein the transform scheme determining selects the transform coefficient based on the each calculated rate-distortion cost.   
     
     
         5 . The apparatus of  claim 2 , wherein the first transforming unit comprises:
 a discrete cosine transforming unit to generate a first image coefficient by performing a DCT on the target image;   a quantizing unit to generate the first transform coefficient by quantizing the first image coefficient;   a DCT coefficient threshold unit to perform a coefficient threshold operation on the quantized first transform coefficient;   an inverse-quantizing unit to perform inverse quantization on the coefficient threshold-operated first transform coefficient; and   a discrete cosine inverse transforming unit to generate the first decoded image of the target image by performing discrete cosine inverse transform on the inverse-quantized first transform coefficient,   wherein the transform scheme determining unit selects the transform coefficient based on the first decoded image.   
     
     
         6 . The apparatus of  claim 2 , wherein the second transforming unit comprises:
 a discrete sine transforming unit to generate a second image coefficient by performing a DST on the target image;   a quantizing unit to generate the second transform coefficient by quantizing the second image coefficient;   a DST coefficient threshold unit to perform a coefficient threshold operation on the quantized second transform coefficient;   an inverse-quantizing unit to perform inverse quantization on the coefficient threshold-operated second transform coefficient; and   a discrete sine inverse transforming unit to generate the second decoded image of the target image by performing discrete sine inverse transform on the inverse-quantized second transform coefficient,   wherein the transform scheme determining unit selects the transform coefficient based on the second decoded image.   
     
     
         7 . The apparatus of  claim 1 , further comprising:
 a transform scheme storage unit to store information about a transform scheme corresponding to the transform coefficient of the target image.   
     
     
         8 . The apparatus of  claim 7 , wherein the transform scheme storage unit stores the information about the transform scheme based on a coded block pattern (CBP) value with respect to the transform coefficient. 
     
     
         9 . The apparatus of  claim 1 , further comprising:
 an image predicting unit to generate a prediction image with respect to an input image based on a reference image with respect to the input image, and to calculate a difference between the input image and the prediction image as the target image.   
     
     
         10 . An apparatus of decoding an image, comprising:
 a transform scheme decision unit to decide a transform scheme with respect to a transform coefficient;   a first inverse transforming unit to generate a decoded image with respect to the transform coefficient by using a discrete cosine inverse transform scheme, when the transform scheme is a DCT; and   a second inverse transforming unit to generate the decoded image with respect to the transform coefficient by using a discrete sine inverse transform scheme, when the transform scheme is a DST.   
     
     
         11 . The apparatus of  claim 10 , wherein the transform scheme decision unit decides the transform scheme by using transform scheme information included in a macroblock header with respect to the transform coefficient. 
     
     
         12 . The apparatus of  claim 11 , wherein the transform scheme information is stored based on a CBP value with respect to the transform coefficient. 
     
     
         13 . The apparatus of  claim 10 , wherein the first inverse transforming unit comprises:
 an inverse quantizing unit to quantize the transform coefficient; and   a discrete since inverse transforming unit to generate the decoded image by performing a discrete cosine inverse transform on the inverse-quantized transform coefficient.   
     
     
         14 . The apparatus of  claim 10 , wherein the second inverse transforming unit comprises:
 an inverse quantizing unit to quantize the transform coefficient; and   discrete sine inverse transforming unit to generate the decoded image by performing a discrete sine inverse transform on the inverse-quantized transform coefficient.   
     
     
         15 . The apparatus of  claim 10 , further comprising:
 an image restoring unit to generate a prediction image with respect to the transform coefficient based on a reference image with respect to the transform coefficient, and to generate a restoration image with respect to the transform coefficient based on the prediction image and the decoded image.   
     
     
         16 . An apparatus of coding an image, comprising:
 a first transforming unit to generate a first transform coefficient by performing a DCT with respect to a target image;   a second transforming unit to generate a second transform coefficient by performing a DST with respect to the target image; and   a transform scheme determining unit to select one of the first transform coefficient and the second transform coefficient as a transform coefficient with respect to the target image.   
     
     
         17 . The apparatus of  claim 16 , further comprising:
 a transform scheme storage unit to store, in a macroblock header with respect to the target image, the transform scheme information with respect to the selected transform coefficient.   
     
     
         18 . The apparatus of  claim 17 , wherein the transform scheme storage unit does not store the transform scheme information when a CBP value with respect to the transform coefficient is “0”. 
     
     
         19 . The apparatus of  claim 16 , further comprising:
 an image predicting unit to generate a prediction image with respect to an input image based on a reference image with respect to the input image, and to calculate a difference between the input image and the prediction image as the target image.   
     
     
         20 . The apparatus of  claim 16 , further comprising:
 a rate-distortion cost calculator to calculate a rate-distortion cost of a decoded image with respect to the first transform coefficient, and to calculate a rate-distortion cost of a decoded image with respect to the second transform coefficient,   wherein the transform scheme determining unit selects the transform coefficient based on each calculated rate-distortion cost.