Image Color Frequency Program

// Classes
import java.io.File;
import java.io.FileWriter;
import java.util.HashMap;
import java.io.IOException;
import javax.imageio.ImageIO;
import java.awt.image.BufferedImage;

public class ImageReader {
    BufferedImage Image;
    HashMap<String, HashMap<Integer, Integer>> Channels = new HashMap<>();

    public ImageReader(String path) throws IOException {
        Image = ImageIO.read(new File("images/" + path));

        // Initialize Channels
        Channels.put("R", new HashMap<>());
        Channels.put("G", new HashMap<>());
        Channels.put("B", new HashMap<>());
    }

    public void read() throws IOException {
        for (int i = 0; i < Image.getWidth(); i++) {
            for (int j = 0; j < Image.getHeight(); j++) {
                for (HashMap.Entry<String, Integer> entry : readPixel(Image.getRGB(i, j)).entrySet()) {
                    Channels.get(entry.getKey()).merge(entry.getValue(), 1, Integer::sum);
                }
            }
        }

        generateFile();
    }

    public void generateFile() throws IOException {
        new File("C:\\Users\\Larry\\Desktop\\histogram.txt");
        FileWriter histogram = new FileWriter("C:\\Users\\Larry\\Desktop\\histogram.txt");

        // Display Histogram
        String content = String.valueOf(buildFrequency("R")) + buildFrequency("G") + buildFrequency("B");
        histogram.write(content);

        histogram.close();
    }

    private StringBuilder buildFrequency(String key) {
        StringBuilder component = new StringBuilder();
        HashMap<Integer, Integer> channel = Channels.get(key);

        // Build
        component.append("Histogram data for ").append(key).append(" channel:\n");

        for (int channelKey = 0; channelKey <= 255; channelKey++) {
            Integer frequency = channel.get(channelKey);
            component.append(channelKey).append(" -> ").append(frequency != null ? frequency : 0).append("\n");
        }

        return component.append("\n");
    }

    private HashMap<String, Integer> readPixel(int pixel) {
        HashMap<String, Integer> rgb = new HashMap<>();

        rgb.put("R", pixel >> 16 & 255);
        rgb.put("G", pixel >> 8 & 255);
        rgb.put("B", pixel & 255);

        return rgb;
    }
}