Learn OpenCV习题解—chapter3

网上已经有很多答案了，我这里只是记一下自己的，没啥创新或者参考意义：）

1. a>cvAbs和cvRound; b>cvRandInt和cvRandReal;c>cvPoint2D32f,cvPointFrom32f;d>cvPointTo32f

2.

    CvMat *matrix=cvCreateMat(100,100,CV_8UC3);
    assert(matrix);
    cvZero(matrix);
    cvCircle(matrix,cvPoint(50,50),50,CV_RGB(255,0,0));


    cvNamedWindow("ex3_2",1);
    cvShowImage("ex3_2",matrix);
    cvReleaseMat(&matrix);
    cvWaitKey();
    cvDestroyWindow("ex3_2");

3.

    CvMat *matrix=cvCreateMat(100,100,CV_8UC3);
    assert(matrix);
    cvZero(matrix);

    for(UINT i=20;i<=40;++i)
        for(UINT j=5;j<=20;++j)
        {
            uchar *ptr=(uchar *)cvPtr2D(matrix,i,j);
            ptr[1]=255;
        }

    cvNamedWindow("ex3_3",1);
    cvShowImage("ex3_3",matrix);
    cvWaitKey();
    cvReleaseMat(&matrix);
    cvDestroyWindow("ex3_3");

4.

    CvMat *matrix=cvCreateMat(100,100,CV_8UC3);
    assert(matrix);
    cvZero(matrix);

    for(size_t i=20;i<=40;++i)
    {
        uchar *ptr=matrix->data.ptr+i*matrix->step;
        for(size_t j=5;j<=20;++j)
        {
            ptr[j*3+1]=255;
        }
    }
    cvNamedWindow("ex3_4",1);
    cvShowImage("ex3_4",matrix);
    cvWaitKey();
    cvReleaseMat(&matrix);
    cvDestroyWindow("ex3_3");

5.

    IplImage *img=cvCreateImage(cvSize(210,210),
        IPL_DEPTH_8U,1);
    assert(img);
    cvZero(img);

    size_t beginPoint=0;
    double beginColor=70;
    while(beginPoint<=200)
    {
        cvSetImageROI(img,cvRect(beginPoint,beginPoint,
            img->width-beginPoint,img->height-beginPoint));
        cvSet(img,cvScalar(beginColor));
        cvResetImageROI(img);
        beginPoint+=20;
        beginColor+=10;
        if(beginColor>255)beginColor=70;
    }

    cvNamedWindow("ex3_5",1);
    cvShowImage("ex3_5",img);
    cvWaitKey();
    cvReleaseImage(&img);
    cvDestroyWindow("ex3_5");

6.

    IplImage *img=cvLoadImage(".\\testimage.JPG");
    assert(img);

    IplImage *header1=cvCreateImageHeader(cvSize(20,30),img->depth,
        img->nChannels);
    IplImage *header2=cvCreateImageHeader(cvSize(20,30),img->depth,
        img->nChannels);
    assert(header1 && header2);
    header1->origin=header2->origin=img->origin;
    header1->widthStep=header2->widthStep=img->widthStep;

    header1->imageData=(char *)cvPtr2D(img,5,10);
    header2->imageData=(char *)cvPtr2D(img,50,60);

    cvNot(header1,header1);
    cvNot(header2,header2);

    cvNamedWindow("ex3_6",1);
    cvShowImage("ex3_6",img);
    cvWaitKey();
    cvReleaseImage(&img);
    cvDestroyWindow("ex3_6");

7.

    IplImage *img=cvLoadImage(".\\testimage.JPG");
    assert(img);

    IplImage *red_image=cvCreateImage(cvSize(img->width,img->height),
        img->depth,1);
    IplImage *green_image=cvCreateImage(cvSize(img->width,img->height),
        img->depth,1);
    IplImage *blue_image=cvCreateImage(cvSize(img->width,img->height),
        img->depth,1);
    assert(red_image && green_image && blue_image);

    cvSplit(img,red_image,green_image,blue_image,0);
    //a
    cvNamedWindow("ex3_7_a",1);
    cvShowImage("ex3_7_a",green_image);
    cvWaitKey();
    cvDestroyWindow("ex3_7_a");

    //b
    IplImage *clone1=cvCloneImage(green_image);
    IplImage *clone2=cvCloneImage(green_image);

    //c
    double max,min;
    cvMinMaxLoc(green_image,&min,&max);

    //d
    double thresh=(max-min)/2.0;
    cvSet(clone1,cvScalar(thresh));

    //e
    cvZero(clone2);
    cvCmp(green_image,clone1,clone2,CV_CMP_GE);

    //f
    cvSubS(green_image,cvScalar(thresh/2.0),green_image,
        clone2);
    cvNamedWindow("ex3_7_f",1);
    cvShowImage("ex3_7_f",green_image);
    cvWaitKey();
    cvReleaseImage(&green_image);
    cvDestroyWindow("ex3_7_f");

8.

struct my_struct
{
    int n;
    CvPoint point;
    CvRect Rect;
};
void write_my_struct(CvFileStorage *fs,
                     const char *name,
                     my_struct *ms)
{
    assert(fs && ms);
    cvStartWriteStruct(fs,name,CV_NODE_SEQ);

    cvWriteInt(fs,"n",ms->n);

    cvStartWriteStruct(fs,"point",CV_NODE_SEQ);
    cvWriteInt(fs,0,ms->point.x);
    cvWriteInt(fs,0,ms->point.y);
    cvEndWriteStruct(fs);

    cvStartWriteStruct(fs,"Rect",CV_NODE_SEQ);
    cvWriteInt(fs,0,ms->Rect.height);
    cvWriteInt(fs,0,ms->Rect.width);
    cvWriteInt(fs,0,ms->Rect.x);
    cvWriteInt(fs,0,ms->Rect.y);
    cvEndWriteStruct(fs);

    cvEndWriteStruct(fs);
}
void read_my_struct(CvFileStorage *fs,
                    CvFileNode *ms_node,
                    my_struct *ms)
{
    assert(ms && fs);
    ms->n=cvReadIntByName(fs,ms_node,"n");

    CvSeq *seq=cvGetFileNodeByName(fs,ms_node,"point")->data.seq;
    assert(seq);
    ms->point.x=cvReadInt((CvFileNode *)cvGetSeqElem(seq,0));
    ms->point.y=cvReadInt((CvFileNode *)cvGetSeqElem(seq,1));

    seq=cvGetFileNodeByName(fs,ms_node,"Rect")->data.seq;
    assert(seq);
    ms->Rect.height=cvReadInt((CvFileNode *)cvGetSeqElem(seq,0));
    ms->Rect.width=cvReadInt((CvFileNode *)cvGetSeqElem(seq,1));
    ms->Rect.x=cvReadInt((CvFileNode *)cvGetSeqElem(seq,2));
    ms->Rect.y=cvReadInt((CvFileNode *)cvGetSeqElem(seq,3));

}