###### tags: `東京威力 TEL`

# I. 影像辨識 OpenCV
## <font color="orange"> 04. 控制面板</font>

### <font color="pink">4-1. 創視窗和控制條</font>

函式使用蠻簡單的，直接看著用就好了。

#include <iostream>
#include <opencv2/opencv.hpp>

using namespace std;
using namespace cv;

void callback(int, void*){
}

int main(){
    namedWindow("TrackBar");  // 建立新視窗
    resizeWindow("TrackBar", 640, 320);  // 視窗大小

  // 建立控制條
    createTrackbar("Hue Min", "TrackBar", 0, 179, callback);
    createTrackbar("Hue Max", "TrackBar", 0, 179, callback);
    createTrackbar("Sat Min", "TrackBar", 0, 179, callback);
    createTrackbar("Sat Max", "TrackBar", 0, 179, callback);
    createTrackbar("Val Min", "TrackBar", 0, 179, callback);
    createTrackbar("Val Max", "TrackBar", 0, 179, callback);

    waitKey(0);
    return 0;
}

### <font color="pink">4-2. 控制條值的讀取與默認值</font>
><font color="magenza">getTrackbarPos(控制項目名稱, 視窗名稱)</font>

我們每過0.5秒印出一次控制條上的值，並且設定 `Hue Min` 的初始值為 55。

#include <iostream>
#include <opencv2/opencv.hpp>

using namespace std;
using namespace cv;

void callback(int, void*){
}

int main(){
    namedWindow("TrackBar");
    resizeWindow("TrackBar", 640, 320);

    createTrackbar("Hue Min", "TrackBar", 0, 179, callback);
    createTrackbar("Hue Max", "TrackBar", 0, 179, callback);
    createTrackbar("Sat Min", "TrackBar", 0, 179, callback);
    createTrackbar("Sat Max", "TrackBar", 0, 179, callback);
    createTrackbar("Val Min", "TrackBar", 0, 179, callback);
    createTrackbar("Val Max", "TrackBar", 0, 179, callback);

    // 控制條的默認值(沒設定就是0)
        setTrackbarPos("Hue Min", "TrackBar", 55);
    
    while(true){
    // 讀取控制條的值
        int hue_M = getTrackbarPos("Hue Min", "TrackBar");
        int hue_m = getTrackbarPos("Hue Max", "TrackBar");
        int sat_M = getTrackbarPos("Sat Max", "TrackBar");
        int sat_m = getTrackbarPos("Sat Min", "TrackBar");
        int val_M = getTrackbarPos("Val Max", "TrackBar");
        int val_m = getTrackbarPos("Val Min", "TrackBar");

        printf("Hue: %d ~ %d\n", hue_m, hue_M);
        printf("Sat: %d ~ %d\n", sat_m, sat_M);
        printf("Val: %d ~ %d\n===\n", val_m, val_M);
        waitKey(500);
    }

    waitKey(0);
    return 0;
}

### <font color="pink">4-3. 過濾顏色</font>

左為 HSV，右邊為原圖。


左為控制板，右為過濾後只留身體的圖。


流程是先將圖片從 BGR 轉 HSV，再用 `TrackBar` 調整 HSV 三個參數，盡量濾出粉粉的肉體。

><font color= "magenza"> void inRange(原圖，HSV下界，HSV上界，輸出圖)</font>

注意到上述 `HSV上下界` 是 `cv::Scalar`，宣告時傳入三個參數的建構子即可。(行35、行36)

#include <iostream>
#include <opencv2/opencv.hpp>

using namespace std;
using namespace cv;

int main(){
    string path = "patrick.png";
    Mat img = imread(path);
    Mat img_hsv;
    Mat mask;  // 過濾圖片

    resize(img, img, Size(img.cols/2, img.rows/2));
    cvtColor(img, img_hsv, COLOR_BGR2HSV);  // 要對 hsv 過濾

    namedWindow("tracker");
    resizeWindow("tracker", 500, 500);

    createTrackbar("Hue Min", "tracker", 0, 179);
    createTrackbar("Hue Max", "tracker", 0, 179);
    createTrackbar("Sat Min", "tracker", 0, 255);
    createTrackbar("Sat Max", "tracker", 0, 255);
    createTrackbar("Val Min", "tracker", 0, 255);
    createTrackbar("Val Max", "tracker", 0, 255);

while(true){
    int hue_m = getTrackbarPos("Hue Min", "tracker");
    int hue_M = getTrackbarPos("Hue Max", "tracker");
    int sat_m = getTrackbarPos("Sat Min", "tracker");
    int sat_M = getTrackbarPos("Sat Max", "tracker");
    int val_m = getTrackbarPos("Val Min", "tracker");
    int val_M = getTrackbarPos("Val Max", "tracker");
  
// Scalar 實例 lower, upper
    Scalar lower(hue_m, sat_m, val_m); 
    Scalar upper(hue_M, sat_M, val_M);
// 將 img_hsv 過濾至 mask 
    inRange(img_hsv, lower, upper, mask);

    imshow("image", img);
    imshow("img_hsv", img_hsv);
    imshow("mask", mask);

    if(waitKey(1) == 27) break;
}
    return 0;
}

以下是寫好的一個函式，輸入原始圖片，輸出 mask 和 TrackBar。

void tracker(Mat img){
    Mat img_hsv, mask, result; 

    cvtColor(img, img_hsv, COLOR_BGR2HSV);

    namedWindow("track_bar");
    resizeWindow("track_bar", 500, 500);

    createTrackbar("Hue Min", "track_bar", 0, 179);
    createTrackbar("Hue Max", "track_bar", 0, 179);
    createTrackbar("Sat Min", "track_bar", 0, 255);
    createTrackbar("Sat Max", "track_bar", 0, 255);
    createTrackbar("Val Min", "track_bar", 0, 255);
    createTrackbar("Val Max", "track_bar", 0, 255);

    setTrackbarPos("Hue Max", "track_bar", 179);
    setTrackbarPos("Sat Max", "track_bar", 255);
    setTrackbarPos("Val Max", "track_bar", 255);

    while(true){
        int hue_m = getTrackbarPos("Hue Min", "track_bar");
        int hue_M = getTrackbarPos("Hue Max", "track_bar");
        int sat_m = getTrackbarPos("Sat Min", "track_bar");
        int sat_M = getTrackbarPos("Sat Max", "track_bar");
        int val_m = getTrackbarPos("Val Min", "track_bar");
        int val_M = getTrackbarPos("Val Max", "track_bar");

        Scalar lower(hue_m, sat_m, val_m);
        Scalar upper(hue_M, sat_M, val_M);
        inRange(img_hsv, lower, upper, mask);

    // // usage: debug
    //     printf("Hue: %d ~ %d\n", hue_m, hue_M);
    //     printf("Sat: %d ~ %d\n", sat_m, sat_M);
    //     printf("Val: %d ~ %d\n===\n", val_m, val_M);

        imshow("img", img);
        imshow("Mask", mask);
        if(waitKey(1) ==27) break;
    }
}

### <font color="pink">4-4. 遮罩原圖</font>
效果如下，原圖（左）、過濾（右）：

 

原圖進行遮罩後：


上圖成功過濾出派大星的身體(和沙灘背景)，會用到 `bitwise_and()`。
遮罩意思是將「原圖」和「參考圖」或「單通道過濾圖」做布林運算並輸出。
例如在上面的例子中，過濾圖中的白色部分會在原圖中保留，反之變為黑色。
> <font color="magenza">bitwise(輸入圖檔一, 輸入圖檔二, 輸出圖檔, 遮罩)</font>

特別注意到行45，在遮罩前要先「讓輸出圖檔的大小和原圖相同」，不然無法遮罩。

#include <iostream>
#include <opencv2/opencv.hpp>

using namespace std;
using namespace cv;

void tracker(Mat img){
    Mat img_hsv, mask, result; 

    cvtColor(img, img_hsv, COLOR_BGR2HSV);

    namedWindow("track_bar");
    resizeWindow("track_bar", 500, 500);

    createTrackbar("Hue Min", "track_bar", 0, 179);
    createTrackbar("Hue Max", "track_bar", 0, 179);
    createTrackbar("Sat Min", "track_bar", 0, 255);
    createTrackbar("Sat Max", "track_bar", 0, 255);
    createTrackbar("Val Min", "track_bar", 0, 255);
    createTrackbar("Val Max", "track_bar", 0, 255);

    setTrackbarPos("Hue Max", "track_bar", 179);
    setTrackbarPos("Sat Max", "track_bar", 255);
    setTrackbarPos("Val Max", "track_bar", 255);

    while(true){
        int hue_m = getTrackbarPos("Hue Min", "track_bar");
        int hue_M = getTrackbarPos("Hue Max", "track_bar");
        int sat_m = getTrackbarPos("Sat Min", "track_bar");
        int sat_M = getTrackbarPos("Sat Max", "track_bar");
        int val_m = getTrackbarPos("Val Min", "track_bar");
        int val_M = getTrackbarPos("Val Max", "track_bar");

        Scalar lower(hue_m, sat_m, val_m);
        Scalar upper(hue_M, sat_M, val_M);
        inRange(img_hsv, lower, upper, mask);
        
    // // usage: debug
    //     printf("Hue: %d ~ %d\n", hue_m, hue_M);
    //     printf("Sat: %d ~ %d\n", sat_m, sat_M);
    //     printf("Val: %d ~ %d\n===\n", val_m, val_M);

        imshow("Img", img);
        imshow("Mask", mask);
        
    // 先讓 Mat result 和 Mat img 大小一樣
        result = Mat::zeros(img.size(), CV_8UC3);
    // 才能使用 bitwise_and()
        bitwise_and(img, img, result, mask);
        imshow("Result", result);
        
        if(waitKey(1) ==27) break;
    }
}

int main(){
    string path = "patrick.png";
    Mat img = imread(path);
    resize(img, img, Size(img.cols/2, img.rows/2));

    tracker(img);
    return 0;
}

`bitwise_and()` 一個更常見的用法是只使用前三個參數，對兩個不同的輸入圖檔做布林運算。