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算法设计步骤：
由RGB图像转到HSV（H：色调，S：饱和度，V：亮度），利用hsv在绿幕背景中的颜色范围是，使用inRang函数进行二值
代码：
#include <opencv2/opencv.hpp>
#include <iostream>
using namespace cv;
using namespace std;
Mat replace_and_blend(Mat &frame, Mat &mask);
Mat background_01;
Mat background_02;
int main(int argc, char** argv) {
// start here...
background_01 = imread("bg001.jpg");
background_02 = imread("bg004.jpg");
Mat sizeImg = imread("标准尺寸.png");
if (background_01.empty() || background_02.empty())
{
printf("could not load image...\n");
return -1;
}
resize(background_01, background_01, Size(sizeImg.cols, sizeImg.rows), 0, 0, INTER_LINEAR);
resize(background_02, background_02, Size(sizeImg.cols, sizeImg.rows), 0, 0, INTER_LINEAR);
VideoCapture capture;
capture.open("01.mp4");
if (!capture.isOpened()) {
printf("could not find the video file...\n");
return -1;
}
char* title = "input video";
char* resultWin = "result video";
namedWindow(title, 0);
namedWindow(resultWin, 0);
Mat frame, hsv, mask;
Mat mask_erode, mask_blur, mask_close;
int count = 0;
while (capture.read(frame)) {
cvtColor(frame, hsv, COLOR_BGR2HSV);
/*
从读取像素到转到hsv空间，后经过inRang的处理，这个处理类似于threshold二值（只能处理单通道的图像），
通过上下限的方式二值(可处理单通道或多通道)，经过这个处理后得到一个二值化的Mat，因为inRang后的图像边缘存在噪点
使用通过形态学闭操作消除小白点，得到的图像进行边缘羽化处理
羽化处理：使用腐蚀的方法将人物的mask向外腐蚀一个边界像素，
然后用高斯模糊，进行梯度边缘处理，得到最终的预处理效果
*/
inRange(hsv, Scalar(35, 43, 46), Scalar(155, 255, 255), mask);
// 形态学操作
Mat k = getStructuringElement(MORPH_RECT, Size(3, 3), Point(-1, -1));
morphologyEx(mask, mask_close, MORPH_CLOSE, k);
erode(mask_close, mask_erode, k);
GaussianBlur(mask_erode, mask_blur, Size(3, 3), 0, 0);
Mat result = replace_and_blend(frame, mask_blur);
char c = waitKey(30);
if (c == 27) {
break;
}
imshow(resultWin, result);
imshow(title, frame);
}
waitKey(0);
return 0;
}
Mat replace_and_blend(Mat &frame, Mat &mask) {
Mat result = Mat::zeros(frame.size(), frame.type());
int h = frame.rows;
int w = frame.cols;
int dims = frame.channels();
// replace and blend
int m = 0;
double wt = 0;
int r = 0, g = 0, b = 0;
int r1 = 0, g1 = 0, b1 = 0;
int r2 = 0, g2 = 0, b2 = 0;
for (int row = 0; row < h; row++) {
uchar* current = frame.ptr<uchar>(row);
uchar* bgrow = background_02.ptr<uchar>(row);
uchar* maskrow = mask.ptr<uchar>(row);
uchar* targetrow = result.ptr<uchar>(row);
for (int col = 0; col < w; col++) {
m = *maskrow++;
if (m == 255) { // 背景
*targetrow++ = *bgrow++;
*targetrow++ = *bgrow++;
*targetrow++ = *bgrow++;
current += 3;
}
else if (m == 0) {// 前景
*targetrow++ = *current++;
*targetrow++ = *current++;
*targetrow++ = *current++;
bgrow += 3;
}
else {
b1 = *bgrow++;
g1 = *bgrow++;
r1 = *bgrow++;
b2 = *current++;
g2 = *current++;
r2 = *current++;
// 权重
wt = m / 255.0;
// 混合
b = b1*wt + b2*(1.0 - wt);
g = g1*wt + g2*(1.0 - wt);
r = r1*wt + r2*(1.0 - wt);
*targetrow++ = b;
*targetrow++ = g;
*targetrow++ = r;
}
}
}
return result;
}
效果：
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