7. 对一幅灰度图像进行离散余弦变换，用图像的形式显示其变换系数。变换后去掉小于系数最大值60% 、80%、90%的系数，在进行反变换，观察变换前后图像区别。

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#include <cxcore.h>#include <cv.h>#include <highgui.h>void cvDcT(CvArr * src_arr, CvArr * dst_arr){    CvMat * tmp;    CvMat q1stub, q2stub;    CvMat q3stub, q4stub;    CvMat d1stub, d2stub;    CvMat d3stub, d4stub;    CvMat * q1, *q2, *q3, *q4;    CvMat * d1, *d2, *d3, *d4;    CvSize size = cvGetSize(src_arr);    CvSize dst_size = cvGetSize(dst_arr);    int cx, cy;    if (dst_size.width != size.width ||        dst_size.height != size.height){        cvError(CV_StsUnmatchedSizes, "cvShiftDFT", "Source and Destination arrays must have equal sizes", __FILE__, __LINE__);    }    if (src_arr == dst_arr){        tmp = cvCreateMat(size.height / 2, size.width / 2, cvGetElemType(src_arr));    }    cx = size.width / 2;    cy = size.height / 2;    q1 = cvGetSubRect(src_arr, &q1stub, cvRect(0, 0, cx, cy));    q2 = cvGetSubRect(src_arr, &q2stub, cvRect(cx, 0, cx, cy));    q3 = cvGetSubRect(src_arr, &q3stub, cvRect(cx, cy, cx, cy));    q4 = cvGetSubRect(src_arr, &q4stub, cvRect(0, cy, cx, cy));    d1 = cvGetSubRect(dst_arr, &d1stub, cvRect(0, 0, cx, cy));    d2 = cvGetSubRect(dst_arr, &d2stub, cvRect(cx, 0, cx, cy));    d3 = cvGetSubRect(dst_arr, &d3stub, cvRect(cx, cy, cx, cy));    d4 = cvGetSubRect(dst_arr, &d4stub, cvRect(0, cy, cx, cy));    if (src_arr != dst_arr){        if (!CV_ARE_TYPES_EQ(q1, d1)){            cvError(CV_StsUnmatchedFormats, "cvShiftDFT", "Source and Destination arrays must have the same format", __FILE__, __LINE__);        }        cvCopy(q3, d1, 0);        cvCopy(q4, d2, 0);        cvCopy(q1, d3, 0);        cvCopy(q2, d4, 0);    }    else{        cvCopy(q3, tmp, 0);        cvCopy(q1, q3, 0);        cvCopy(tmp, q1, 0);        cvCopy(q4, tmp, 0);        cvCopy(q2, q4, 0);        cvCopy(tmp, q2, 0);    }}int main(int argc, char ** argv){    const char* filename = argc >= 2 ? argv[1] : "2.bmp";    IplImage * im;    IplImage * realInput;    IplImage * imaginaryInput;    IplImage * complexInput;    int dft_M, dft_N;    CvMat* dft_A, tmp;    IplImage * image_Re;    IplImage * image_Im;    double m, M;    im = cvLoadImage("6013202130.bmp", CV_LOAD_IMAGE_GRAYSCALE);    if (!im)        return -1;    realInput = cvCreateImage(cvGetSize(im), IPL_DEPTH_64F, 1);    imaginaryInput = cvCreateImage(cvGetSize(im), IPL_DEPTH_64F, 1);    complexInput = cvCreateImage(cvGetSize(im), IPL_DEPTH_64F, 2);    cvScale(im, realInput, 1.0, 0.0);    cvZero(imaginaryInput);    cvMerge(realInput, imaginaryInput, NULL, NULL, complexInput);    dft_M = cvGetOptimalDFTSize(im->height - 1);    dft_N = cvGetOptimalDFTSize(im->width - 1);    dft_A = cvCreateMat(dft_M, dft_N, CV_64FC2);    image_Re = cvCreateImage(cvSize(dft_N, dft_M), IPL_DEPTH_64F, 1);    image_Im = cvCreateImage(cvSize(dft_N, dft_M), IPL_DEPTH_64F, 1);    cvGetSubRect(dft_A, &tmp, cvRect(0, 0, im->width, im->height));    cvCopy(complexInput, &tmp, NULL);    if (dft_A->cols > im->width)    {        cvGetSubRect(dft_A, &tmp, cvRect(im->width, 0, dft_A->cols - im->width, im->height));        cvZero(&tmp);    }    cvDFT(dft_A, dft_A, CV_DXT_FORWARD, complexInput->height);    cvNamedWindow("原图6013202130", 0);    cvNamedWindow("变换后", 0);    cvShowImage("原图6013202130", im);    cvSplit(dft_A, image_Re, image_Im, 0, 0);    cvPow(image_Re, image_Re, 2.0);    cvPow(image_Im, image_Im, 2.0);    cvAdd(image_Re, image_Im, image_Re, NULL);    cvPow(image_Re, image_Re, 0.5);    cvAddS(image_Re, cvScalarAll(1.0), image_Re, NULL);    cvLog(image_Re, image_Re);    cvDcT(image_Re, image_Re);    cvMinMaxLoc(image_Re, &m, &M, NULL, NULL, NULL);    cvScale(image_Re, image_Re, 1.0 / (M - m), 1.0*(-m) / (M - m));    cvShowImage("变换后", image_Re);    cvWaitKey(-1);    return 0;}
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