opencv 相关函数集合

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/* 合并多图像矩阵到一个大矩阵上 */
Mat mergeImgMats(vector<Mat> img_mats, int per_width, int per_height, int cols, int split_w) {
    int count = img_mats.size();
    CV_Assert(count > 0);
    // 定义 行
    int rows = count % cols == 0 ? count / cols : count / cols + 1;
 
    //准备一个大矩阵
    Mat bigMat(per_height * rows + split_w * (rows - 1), per_width*cols + split_w * (cols - 1), img_mats[0].type());
    bigMat.setTo(Scalar::all(0));
    Mat tmp;
    for (size_t i = 0; i < count; i++)
    {
        resize(img_mats[i], tmp, Size(per_width, per_height));
 
        int location_x = 0, location_y = 0;;
        //copy to location
        if (i < cols) { //第一行
            location_x = i * (per_width + split_w);
            location_y = 0;
        }
        else
        { // 第二行开始
            location_x = i % cols * (per_width + split_w);
            location_y = i / cols * (per_height + split_w);
        }
        Mat roi = bigMat(Rect(location_x, location_y, per_width, per_height));
        tmp.copyTo(roi);
    }
 
    tmp.release();
    return bigMat;
}
 
 
int BGR2YUV420P(Mat img, uint8_t *yuv_data, int w, int h) {
    assert(w % 2 == 0 && h % 2 == 0);
    Mat yuv;
    cvtColor(img, yuv, CV_BGR2YUV_I420);  //CV_BGR2YUV_I420
 
    Mat Y = yuv(Rect(0, 0, w, h));
    Mat U = yuv(Rect(0, h, w / 2, h / 2));
    Mat V = yuv(Rect(w / 2, h, w / 2, h / 2));
 
    memcpy_s(yuv_data, w * h, Y.data, h * w);
    for (size_t i = 0; i < h / 2; i++)
    {
        for (size_t j = 0; j < w; j++)
        {
            int index = i * w + j;
            if (j < 2 / w) yuv_data[w*h + index] = U.data[index];
            else yuv_data[w*h + index] = V.data[index - w / 2];
        }
    }
    yuv.release();
 
    return 0;
}
 
# YUV --> AVI 
# 只适用于YUV格式数据直接存储的视频文件
int YuvFile_to_AviFile(string &yuv_filename, int src_img_w, int src_img_h, string &avi_filenanme, int dst_img_w, int dst_img_h) {
    int img_w = src_img_w, img_h = src_img_h;
    int scale_w = dst_img_w, scale_h = dst_img_h;
 
    int yuv_size = img_w * img_h * 3 / 2;
    FILE *f = NULL;
    uint8_t *yuv_data = new uint8_t[yuv_size];
    auto code = fopen_s(&f, yuv_filename.c_str(), "rb");
    assert(code == 0);
    Mat img(img_h, img_w, CV_8UC3);
    Mat yuvFrame(img_h * 3 / 2, img_w, CV_8UC1, yuv_data);
 
    VideoWriter newcw;
    auto flag = newcw.open(avi_filenanme, CV_FOURCC('M', 'P', '4', '2'), 25.0, Size(scale_w, scale_h));
    assert(true == flag);
 
    while (1)
    {
        auto _size = fread_s(yuv_data, yuv_size, 1, yuv_size, f);
        if (_size < yuv_size) {
            break;
        }
 
        cvtColor(yuvFrame, img, CV_YUV420p2RGB);
        assert(img.empty() == false && img.cols > 0);
 
        if (scale_w != img_w || scale_h != img_h) {
            resize(img, img, Size(scale_w, scale_h));
        }
        newcw.write(img);
    }
 
    yuvFrame.release();
    img.release();
    delete[] yuv_data;
    fclose(f);
    newcw.release();
 
    return 0;
}
 
 
 
# 编码
static  unsigned char* img2Encode(Mat src, int& dataLength) {
    vector<unsigned char> inImage;
    imencode(".jpg", src, inImage);
    size_t datalen = inImage.size();
    unsigned char *outImage = new unsigned char[datalen];
    for (int i = 0; i < datalen; i++)
    {
        outImage[i] = inImage[i];
    }
    inImage.clear();
    dataLength = datalen;
 
    return outImage;
}
 
# 解码
static Mat img2Decode(unsigned char *inImage, int dataLength) {
    vector<unsigned char> buff;
    for (int i = 0; i < dataLength; i++)
    {
        buff.push_back(inImage[i]);
    }
    Mat mat = imdecode(buff, CV_LOAD_IMAGE_COLOR);
    buff.clear();
 
    return mat;
}