Hi, I'm new to java and I'm trying to get my program to run where it takes one photo of me at a green screen and then substitutes it for another background.

I have all the code that grabs the pictures but I cant quite get it to work correctly. My code so far is as follows;

Java Code:
public class DIP {
public static void chromakey(Picture p1, Picture p2){
		for( int i = 0, j = p1.getHeight()-1; i < p1.getWidth(); i++){
			for( int k = 0, l= p2.getHeight(); k < p2.getWidth()-1; k++){

				int g1 = p1.getGreen(i, j);

				while (g1 > 180 && g1 < 190)
				i=k;
				j=l;
				
				
				
				
					
			}}}
	public static void main(String[] args) {
		
		
		// Choose a file from the filesystem
		ImageFileChooser ifc = new ImageFileChooser();
		String filename = ifc.getFile();
		
		// Create a Picture object
		Picture original = new Picture(filename, "Original Image");
		Picture chrom = new Picture(filename, "Chromakey");
		
		// Show the Picture
		original.displayImage();
		
		
		// Convert Picture to chromakey
		System.out.println("Converting to chromakey.");
		String filename2 = ifc.getFile();
		Picture background = new Picture(filename2, "");
		chromakey(chrom,background);
		chrom.displayImage();
		
		
	}}