opencv 内存中读取一段jpg 图片

    FILE* f=fopen("d:\\background_left.jpg","r");

    unsigned char *m=(unsigned char*)malloc(1280*720);

    fread(m,50000,1,f);

    CvMat mat = cvMat(720,1280,CV_8UC1, m);

    IplImage *p = cvDecodeImage( &mat, 1 );

    cvNamedWindow("a");

    cvShowImage("a",p);

    cvWaitKey(0);