How to remove green pixels from character green screen - c++

Question

I am a beginner with C++, so please forgive me, but I am trying to bring two images together. One of them is a character in a green screen and a real life location. I was able to successfully mix the two images together on Visual Studio, however, I'm trying to remove the green pixels from the character and replace them with the background image. How can I use the green pixels. Any form of help would be much appreciated. Here is my code:
#include <iostream>
#include <SFML/Graphics.hpp>
using namespace sf;
using namespace std;
int main()
{
Texture tex;
if (!tex.loadFromFile("yoda.png")) {
cout << "Couldn’t Load Yoda Image";
exit(1);
}
Texture tex2;
if (!tex2.loadFromFile("prague.png")) {
cout << "Couldn’t Load Prague Image";
exit(1);
}
Image yodaImage;
yodaImage = tex.copyToImage();
Image pragueImage;
pragueImage = tex2.copyToImage();
RenderWindow window(VideoMode(1024, 800), "Assignment 3");
Sprite sprite;
sprite.setTexture(tex);
Vector2u textureSize = tex.getSize();
sprite.setPosition((1024 - textureSize.x) / 2,
(800 - textureSize.y) / 2);
Vector2u sz = yodaImage.getSize();
for (int y = 0; y < sz.y; y++) {
for (int x = 0; x < sz.x; x++) {
Color pragueC = pragueImage.getPixel(x,y);
Color yodaC = yodaImage.getPixel(x,y);
Color mixedC(
pragueC.r / 2 + yodaC.r / 2,
pragueC.g / 2 + yodaC.g / 2,
pragueC.b / 2 + yodaC.b / 2 );
yodaImage.setPixel(0, 0, mixedC);
}
}
tex.loadFromImage(yodaImage);
window.clear();
window.draw(sprite);
window.display();
while (true);
}