OpenCv 014---图像插值（Image interpolation）

男娘i 2021-11-08 17:00 468阅读 0赞

**1 前备知识**

图像在进行几何变换、透视变换等场景时需要插值计算新像素的像素值。

[图像处理之三种常见双立方插值算法 - CSDN博客][- CSDN]

[图像放缩之双立方插值 - CSDN博客][- CSDN 1]

[图像放缩之双线性内插值 - CSDN博客][- CSDN 2]

[图像处理之Lanczos采样放缩算法 - CSDN博客][Lanczos_ - CSDN]

**（1）INTER\_NEAREST最邻近插值**

将离新像素所在位置最近的像素像素值赋值给新像素。计算亮最小。

**（2）双线性插值**

x、y方向临近像素取乘以相应权重并相加赋值给i新的像素值。

**（3）双立方插值**

精度更高，计算量最大，取附近十六个点加权取像素值。

**（4）INTER\_LANCZOS4**

附近像素及原像素加权取值。

**2 所用到的主要OpenCv API**

/\*\* @brief 对一副图像指定x，y方向上的缩放比例进行缩放。

@code  
 // explicitly specify dsize=dst.size(); fx and fy will be computed from that.  
 resize(src, dst, dst.size(), 0, 0, interpolation);  
@endcode  
If you want to decimate the image by factor of 2 in each direction, you can call the function this  
way:  
@code  
 // specify fx and fy and let the function compute the destination image size.  
 resize(src, dst, Size(), 0.5, 0.5, interpolation);  
@endcode  
To shrink an image, it will generally look best with \#INTER\_AREA interpolation, whereas to  
enlarge an image, it will generally look best with c\#INTER\_CUBIC (slow) or \#INTER\_LINEAR  
(faster but still looks OK).

@param src input image.  
@param dst output image; it has the size dsize (when it is non-zero) or the size computed from  
src.size(), fx, and fy; the type of dst is the same as of src.  
@param dsize output image size; if it equals zero, it is computed as:  
 \\f\[\\texttt\{dsize = Size(round(fx\*src.cols), round(fy\*src.rows))\}\\f\]  
 Either dsize or both fx and fy must be non-zero.  
@param fx scale factor along the horizontal axis; when it equals 0, it is computed as  
\\f\[\\texttt\{(double)dsize.width/src.cols\}\\f\]  
@param fy scale factor along the vertical axis; when it equals 0, it is computed as  
\\f\[\\texttt\{(double)dsize.height/src.rows\}\\f\]  
@param interpolation interpolation method, see \#InterpolationFlags

@sa warpAffine, warpPerspective, remap  
 \*/

CV_EXPORTS_W void resize( InputArray src, OutputArray dst,
                              Size dsize, double fx = 0, double fy = 0,
                              int interpolation = INTER_LINEAR );

**3 程序代码**

#include"opencv2\opencv.hpp"
    #include<iostream>
    
    using namespace std;
    using namespace cv;
    
    int main(int argc, char** argv)
    {
        Mat src = imread("G:\\CVworkstudy\\program_wwx\\研习社140课时\\ZhaiZhigang140\\colormap.png");
        if (src.empty())
        {
            printf("Could not load image...\n");
            return -1;
        }
        imshow("srcImg", src);
        Mat dst = Mat::zeros(src.size(), src.type());
        double fx = 0, fy = 0;
        int height = src.rows;
        int width = src.cols;
        //最邻近插值
        resize(src, dst, Size(0, 0), 0.5, 0.5, INTER_NEAREST);//如果Size(0,0),则图像大小为Size(width*fx height*fy)
        imshow("NEAREST", dst);
        //双线性插值
        resize(src, dst, Size(width * 2, height * 2), fx, fy, INTER_LINEAR);
        imshow("LineNear", dst);
        //双立方插值
        resize(src, dst, Size(width * 2, height * 2), fx, fy, INTER_CUBIC);
        imshow("CUBIC", dst);
        //LANCZOS插值
        resize(src, dst, Size(width * 2, height * 2), fx, fy, INTER_LANCZOS4);
        imshow("LANCZOS", dst);
    
        waitKey(0);
        return 0;
    }

**4 运行结果**

**![1321981-20190716144332957-1911126177.png][]**

![1321981-20190716144355784-1019991392.png][]

![1321981-20190716144431606-753847711.png][]

![1321981-20190716144535102-814843486.png][]

**5 扩展及注意事项**

**null**

转载于:https://www.cnblogs.com/Vince-Wu/p/11194910.html

[- CSDN]: https://blog.csdn.net/jia20003/article/details/40020775
[- CSDN 1]: https://blog.csdn.net/jia20003/article/details/6919845
[- CSDN 2]: https://blog.csdn.net/jia20003/article/details/6915185
[Lanczos_ - CSDN]: https://blog.csdn.net/jia20003/article/details/17856859
[1321981-20190716144332957-1911126177.png]: /images/20211108/85939c7bb79a44a89b4ec57c0c2ee846.png
[1321981-20190716144355784-1019991392.png]: /images/20211108/d87924b200c047bc8c28abc0f84ffa65.png
[1321981-20190716144431606-753847711.png]: /images/20211108/af15771bf6e04e9b86fa7ca93a8744ba.png
[1321981-20190716144535102-814843486.png]: /images/20211108/51a1736aaa9f4fa892224ae12885ecfc.png