Memory jpeg encode & decode in openCV

decode :::CvMat *matJpg = cvCreateMat( 1, dwSizeBuffer, CV_8UC1 );CopyMemory( matJpg->data.ptr, pBuffer, dwSizeBuffer );IplImage* pImageFull = cvDecodeImage( matJpg );cvReleaseMat(&matJpg);// do some image manipulation with 'pImageFull'cvReleaseImage(&pImageFull);encode :::IplImage* pImage = cvLoadImage("ddd.bmp" );CvMat *pJpeg = cvEncodeImage( ".jpg", pImage );LPBYTE pBufferJpg = pJpeg->data.ptr;LONG lSizeJPEG = pJpeg->cols;// do some file job with pBufferJpg, lSizeJPEGcvReleaseMat(&pJpeg);cvReleaseImage(&pImage);