diff --git a/pom.xml b/pom.xml
index 55d8067..544e2e2 100644
--- a/pom.xml
+++ b/pom.xml
@@ -19,6 +19,11 @@
             <artifactId>ij</artifactId>
             <version>1.51h</version>
         </dependency>
+        <dependency>
+            <groupId>commons-io</groupId>
+            <artifactId>commons-io</artifactId>
+            <version>2.15.1</version>
+        </dependency>
     </dependencies>
 
 </project>
\ No newline at end of file
diff --git a/src/main/java/org/example/Main.java b/src/main/java/org/example/Main.java
index 8c4f635..aa2f4b9 100644
--- a/src/main/java/org/example/Main.java
+++ b/src/main/java/org/example/Main.java
@@ -2,38 +2,34 @@ package org.example;
 
 import ij.IJ;
 import ij.ImagePlus;
-import ij.process.ImageProcessor;
+import ij.process.ImageConverter;
+import org.apache.commons.io.FilenameUtils;
 
 import java.awt.*;
+import java.awt.image.BufferedImage;
 import java.io.File;
 
-/*
-TODO:
-- Parse properly the CLI arguments
-- Add error handling
-- Write many lines with an angle
-- Write for any image (format & responsiveness)
-- optional: Export to PDF?
- */
-
 public class Main {
     public static void main(String[] args) {
 
         if (args.length == 0)
         {
-            System.out.println("Usage: java -jar watermark.jar <input file> -s <string> [-o <output file>]");
+            System.out.println("librewatmark - libre watermark tool\nUsage: <input file> -s <string> [-o <output file>]");
             System.exit(0);
         }
 
+        String filename = null;
         File f = null;
+        String watermark = null;
+        String outputfile = null;
 
         for (int i=0; i<args.length; i++)
         {
-            System.out.println("Argument " + i + ": " + args[i]);
+            //System.out.println("Argument " + i + ": " + args[i]);
 
             if (i == 0) {
                 // First argument is input file, if not, gtfo here
-                String filename = args[i];
+                filename = args[i];
                 f = new File(filename);
                 if (!f.exists() || f.isDirectory()) {
                     System.out.println("Input file \"" + filename + "\" does not exist.");
@@ -45,10 +41,12 @@ public class Main {
                 case '-':
                     switch (args[i].charAt(1)) {
                         case 's': // -s string: to be put as watermark
-                            System.out.println("OPTION B");
+                            watermark = args[i+1];
+                            i++;
                             break;
                         case 'o': // -o file: output file
-                            System.out.println("OPTION C");
+                            outputfile = args[i+1];
+                            i++;
                             break;
                         default:
                             System.out.println("Unknown argument: \"" + args[i] + "\"");
@@ -59,15 +57,58 @@ public class Main {
             }
         }
 
-        // test
-        ImagePlus image = IJ.openImage(f.getAbsolutePath());
-        Font font = new Font("Arial", Font.PLAIN, 18);
-        ImageProcessor ip = image.getProcessor();
-        ip.setColor(Color.WHITE);
-        ip.setFont(font);
-        ip.drawString("Watermark Text", 10, 20);
-        image.updateAndDraw();
-        IJ.save(image, "output.png");
+        if (outputfile == null)
+        {
+            outputfile = FilenameUtils.removeExtension(filename) + "-watermark";
+        }
 
+        if (watermark == null)
+        {
+            System.out.println("No watermark text provided.");
+            System.exit(1);
+        }
+
+        ImagePlus image = IJ.openImage(f.getAbsolutePath());
+
+        if (image.getType() != ImagePlus.COLOR_RGB) {
+            ImageConverter ic = new ImageConverter(image);
+            ic.convertToRGB();
+        }
+
+        BufferedImage bufferedImage = image.getBufferedImage();
+
+        Graphics2D g2d = bufferedImage.createGraphics();
+        g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
+                RenderingHints.VALUE_ANTIALIAS_ON);
+
+        Font font = new Font("Arial", Font.PLAIN, 18);
+        g2d.setFont(font);
+        g2d.setColor(new Color(0, 0, 0, 180));
+
+        double angle = Math.toRadians(-45);
+        g2d.rotate(angle,
+                bufferedImage.getWidth() / 2.0,
+                bufferedImage.getHeight() / 2.0);
+
+        FontMetrics fm = g2d.getFontMetrics();
+        int textWidth = fm.stringWidth(watermark);
+        int textHeight = fm.getHeight();
+
+        for (int y = -bufferedImage.getHeight(); y < bufferedImage.getHeight() * 2; y += textHeight * 4) {
+            for (int x = -bufferedImage.getWidth(); x < bufferedImage.getWidth() * 2; x += textWidth + 50) {
+                g2d.drawString(watermark, x, y);
+            }
+        }
+
+        g2d.dispose();
+
+        ImagePlus out = new ImagePlus("watermarked", bufferedImage);
+
+        if (!outputfile.matches(".*\\.(png|jpg|jpeg|tif|tiff)$")) {
+            outputfile += ".png";
+        }
+
+        IJ.save(out, outputfile);
+        System.out.println("Watermarked file saved as \"" + outputfile + "\"");
     }
 }
\ No newline at end of file