Figured out, that it wasn't "1", but infact "0". Finished implementation

of getBrightestSpotGrayscale (WARNING ⚠️: untested code). To be done:
Write test cases for all the methods

src/main/java/com/cringe_studios/christmastreescanning/ChristmasTreeScanning.java

@@ -4,8 +4,11 @@ import java.awt.Color;
 import java.awt.Point;
 import java.awt.geom.Point2D;
 import java.awt.image.BufferedImage;
+import java.util.ArrayList;
+import java.util.List;
 
 public class ChristmasTreeScanning {
+	//TODO maybe use Point2D.Double as return type, so the Points don't have to be converted to Points2D later down the pipeline during the normalization step
 	private Point getBrightestSpotGrayscale(BufferedImage grayScaleImage, byte gammaDelta) {
 		int[] imageColors = grayScaleImage.getRGB(0, 0, grayScaleImage.getWidth(), grayScaleImage.getHeight(), null, 0, 0);
 		
@@ -13,9 +16,26 @@ public class ChristmasTreeScanning {
 			imageColors[i] &= 0x0000_00FF; // because the image is grayscale, only one component is needed
 		}
 		
-		//TODO
+		int brightestValue = 0;
 		
-		Point brightestSpot = new Point(0, 0);
+		for(int i = 0; i < imageColors.length; i++) {
+			if(brightestValue < imageColors[i]) {
+				brightestValue = imageColors[i];
+			}
+		}
+		
+		List<Integer> brightSpots = new ArrayList<Integer>();
+		
+		for(int i = 0; i < imageColors.length; i++) {
+			if(imageColors[i] >= brightestValue - gammaDelta) {
+				brightSpots.add(Integer.valueOf(i));
+			}
+		}
+		
+		//The following line might be incorrect; TODO double check and write a test
+		Point brightPoints[] = brightSpots.stream().map(s -> new Point(s.intValue() % grayScaleImage.getWidth(), s.intValue() / grayScaleImage.getWidth())).toArray(Point[]::new);
+		
+		Point brightestSpot = new PointInterpolator(brightPoints).getCenter();
 		
 		return brightestSpot;
 	}
@@ -68,7 +88,7 @@ public class ChristmasTreeScanning {
 	}
 	
 	public Point getBrightestSpot(BufferedImage image) {
-		return getBrightestSpot(image, (byte)1); //TODO is it really 1?
+		return getBrightestSpot(image, (byte)0);
 	}
 	
 	

src/main/java/com/cringe_studios/christmastreescanning/PointInterpolator.java

@@ -3,15 +3,21 @@ package com.cringe_studios.christmastreescanning;
 import java.awt.Point;
 
 public class PointInterpolator {
-	Point a;
-	Point b;
+	Point points[];
 	
-	public PointInterpolator(Point na, Point nb) {
-		a = na;
-		b = nb;
+	public PointInterpolator(Point...na) {
+		points = na;
 	}
 	
 	Point getCenter() {
-		return new Point( (a.x + b.x) / 2, (a.y + b.y) / 2);
+		int xSum = 0;
+		int ySum = 0;
+		
+		for(int i = 0; i < points.length; i++) {
+			xSum += points[i].x;
+			ySum += points[i].y;
+		}
+		
+		return new Point( xSum / 2, ySum / 2);
 	}
 }