[OpenCV] IplImage and Functions

typedef struct _IplImage
{
    int  nSize;             /* sizeof(IplImage) */
    int  ID;                /* version (=0)*/
    int  nChannels;         /* Most of OpenCV functions support 1,2,3 or 4 channels */
    int  alphaChannel;      /* Ignored by OpenCV */
    int  depth;             /* Pixel depth in bits: IPL_DEPTH_8U, IPL_DEPTH_8S, IPL_DEPTH_16S,
                               IPL_DEPTH_32S, IPL_DEPTH_32F and IPL_DEPTH_64F are supported.  */
    char colorModel[4];     /* Ignored by OpenCV */
    char channelSeq[4];     /* ditto */
    int  dataOrder;         /* 0 - interleaved color channels 隔行扫描, 1 - separate color channels .
                               cvCreateImage can only create  images */
    int  origin;            /* 0 - top-left origin,
                               1 - bottom-left origin (Windows bitmaps style).  */
    int  align;             /* Alignment of image rows (4 or 8).
                               OpenCV ignores it and uses widthStep instead.    */
    int  width;             /* Image width in pixels.                           */
    int  height;            /* Image height in pixels.                          */
    struct _IplROI *roi;    /* Image ROI. If NULL, the whole image is selected. 函数的操作被限定在一小块区域*/
    struct _IplImage *maskROI;      /* Must be NULL. */
    void  *imageId;                 /* "           " */
    struct _IplTileInfo *tileInfo;  /* "           " */
    int  imageSize;         /* Image data size in bytes
                               (==image->height*image->widthStep
                               in case of interleaved data)*/
    char *imageData;        /* Pointer to aligned image data.         */
    int  widthStep;         /* Size of aligned image row in bytes.    */
    int  BorderMode[4];     /* Ignored by OpenCV.                     */
    int  BorderConst[4];    /* Ditto.                                 */
    char *imageDataOrigin;  /* Pointer to very origin of image data
                               (not necessarily aligned) -
                               needed for correct deallocation */
}
IplImage;

#include <highgui.h>

int main(void)
{

    IplImage* src;
    cvNamedWindow("Example3_12_pre", CV_WINDOW_AUTOSIZE);
    cvNamedWindow("Example3_12_post", CV_WINDOW_AUTOSIZE);
    if(((src=cvLoadImage("/home/unsw/lolo.jpg",1)) != 0 ))
    {
        int x = atoi("10");
        int y = atoi("20");
        int width = atoi("50");
        int height = atoi("100");
        int add = atoi("100");
        cvShowImage( "Example3_12_pre", src);

        cvSetImageROI(src, cvRect(x,y,width,height));　　//设置专注范围
        cvAddS(src, cvScalar(add, 0, 0, 0), src, NULL);　//只在专注的范围执行函数
        cvResetImageROI(src);　　//如果注销，下一个函数（显示图像）则只会显示指定区域

        cvShowImage( "Example3_12_post",src);
        cvWaitKey(5000);
    }
    cvReleaseImage( &src );
    cvDestroyWindow("Example3_12_pre");
    cvDestroyWindow("Example3_12_post");
    return 0;
}

int main(int argc, char** argv)
{
    IplImage* interest_img;
    CvRect interest_rect;
    if( argc == 7 && ((interest_img=cvLoadImage(argv[1],1)) != 0 ))
    {
        interest_rect.x = atoi(argv[2]);
        interest_rect.y = atoi(argv[3]);
        interest_rect.width = atoi(argv[4]);
        interest_rect.height = atoi(argv[5]);
        int add = atoi(argv[6]);

        // Assuming IplImage *interest_img; and 
        //  CvRect interest_rect;
        //  Use widthStep to get a region of interest
        //
        // (Alternate method)
        //
        IplImage *sub_img = cvCreateImageHeader(
          cvSize(
             interest_rect.width, 
             interest_rect.height
          ),
          interest_img->depth, 
          interest_img->nChannels
        );
        
        sub_img->origin = interest_img->origin;
        
        sub_img->widthStep = interest_img->widthStep;
        
        sub_img->imageData = interest_img->imageData + 
          interest_rect.y * interest_img->widthStep  +
          interest_rect.x * interest_img->nChannels;
        
        cvAddS( sub_img, cvScalar(add), sub_img );
        
        cvReleaseImageHeader(&sub_img);

        cvNamedWindow( "Roi_Add", CV_WINDOW_AUTOSIZE );
        cvShowImage( "Roi_Add", interest_img );
        cvWaitKey();
    }
    return 0;
}