diff --git a/jpro-image-manager/src/main/java/one/jpro/platform/image/manager/ImageDefinition.java b/jpro-image-manager/src/main/java/one/jpro/platform/image/manager/ImageDefinition.java
index dca690d6..4f8443f3 100644
--- a/jpro-image-manager/src/main/java/one/jpro/platform/image/manager/ImageDefinition.java
+++ b/jpro-image-manager/src/main/java/one/jpro/platform/image/manager/ImageDefinition.java
@@ -81,11 +81,10 @@ public ImageEncoder getEncoder() {
 
     /**
      * Computes and returns a hash string representation for this instance.
-     * Note: This method currently returns the default hashCode as a string, which might not guarantee uniqueness.
      *
      * @return A string representing the hash of this instance.
      */
     String getHashString() {
-        return Integer.toString(hashCode());
+        return ImageManager.computeImageDefinitionHash(this);
     }
 }
\ No newline at end of file
diff --git a/jpro-image-manager/src/main/java/one/jpro/platform/image/manager/ImageManager.java b/jpro-image-manager/src/main/java/one/jpro/platform/image/manager/ImageManager.java
index e0f4f234..a8ceecb8 100644
--- a/jpro-image-manager/src/main/java/one/jpro/platform/image/manager/ImageManager.java
+++ b/jpro-image-manager/src/main/java/one/jpro/platform/image/manager/ImageManager.java
@@ -151,7 +151,7 @@ CompletableFuture<Image> loadFXImageFuture(ImageSource source, ImageTransformer
      * @param imageDefinition the image definition
      * @return the computed MD5 hash as a string
      */
-    private String computeImageDefinitionHash(ImageDefinition imageDefinition) {
+    public static String computeImageDefinitionHash(ImageDefinition imageDefinition) {
         try {
             MessageDigest digest = MessageDigest.getInstance("MD5");
             byte[] hashBytes = digest.digest(imageDefinition.toJSON().toString().getBytes(StandardCharsets.UTF_8));
diff --git a/jpro-image-manager/src/main/java/one/jpro/platform/image/manager/source/ImageSourceFile.java b/jpro-image-manager/src/main/java/one/jpro/platform/image/manager/source/ImageSourceFile.java
index 9e7d890c..fad67d35 100644
--- a/jpro-image-manager/src/main/java/one/jpro/platform/image/manager/source/ImageSourceFile.java
+++ b/jpro-image-manager/src/main/java/one/jpro/platform/image/manager/source/ImageSourceFile.java
@@ -69,6 +69,7 @@ public JSONObject toJSON() {
         JSONObject json = new JSONObject();
         json.put("type", getClass().getSimpleName());
         json.put("path", ImageUtils.escapeJson(file.getAbsolutePath()));
+        json.put("modified", file.lastModified());
         return json;
     }
 }
\ No newline at end of file
diff --git a/jpro-image-manager/src/main/java/one/jpro/platform/image/manager/source/ImageSourceResource.java b/jpro-image-manager/src/main/java/one/jpro/platform/image/manager/source/ImageSourceResource.java
index 85f269ec..d6e59583 100644
--- a/jpro-image-manager/src/main/java/one/jpro/platform/image/manager/source/ImageSourceResource.java
+++ b/jpro-image-manager/src/main/java/one/jpro/platform/image/manager/source/ImageSourceResource.java
@@ -67,8 +67,18 @@ public long identityHashValue() {
     public JSONObject toJSON() {
         JSONObject json = new JSONObject();
         json.put("type", getClass().getSimpleName());
-        // Escaping might be necessary depending on the structure of resourcePath.
         json.put("resourcePath", ImageUtils.escapeJson(resourcePath));
+        // get last modified date
+        // It's important, so the images get recreated, when the files in the jar are updated
+        try {
+            URL resourceUrl = getClass().getResource(resourcePath);
+            if (resourceUrl != null) {
+                URLConnection conn = resourceUrl.openConnection();
+                json.put("modified", conn.getLastModified());
+            }
+        } catch (Exception ex) {
+            throw new RuntimeException("Error obtaining modification date for resource: " + resourcePath, ex);
+        }
         return json;
     }
 
diff --git a/jpro-image-manager/src/test/java/one/jpro/platform/image/manager/ImageManagerTest.java b/jpro-image-manager/src/test/java/one/jpro/platform/image/manager/ImageManagerTest.java
index 05e87483..d7fb0366 100644
--- a/jpro-image-manager/src/test/java/one/jpro/platform/image/manager/ImageManagerTest.java
+++ b/jpro-image-manager/src/test/java/one/jpro/platform/image/manager/ImageManagerTest.java
@@ -14,8 +14,12 @@
 import org.junit.jupiter.api.Test;
 import org.mockito.Mockito;
 
+import java.io.IOException;
+import java.nio.file.Files;
+
 import java.awt.image.BufferedImage;
 import java.io.File;
+import java.nio.file.StandardCopyOption;
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.CountDownLatch;
 
@@ -26,6 +30,9 @@ class ImageManagerTest {
 
     ImageManager manager;
     ImageDefinition def;
+    File imageDef2File;
+    ImageDefinition imageDef2;
+
 
 
     @BeforeEach
@@ -44,6 +51,12 @@ void setUp() throws InterruptedException {
         ImageTransformer transformer = new ImageTransformerFitWidth(200);
         ImageEncoder encoder = new ImageEncoderPNG();
         def = new ImageDefinition(source, transformer, encoder);
+
+        imageDef2File = new File("testImage.png");
+        ImageSource source2 = new ImageSourceFile(imageDef2File);
+        ImageTransformer transformer2 = new ImageTransformerFitWidth(200);
+        ImageEncoder encoder2 = new ImageEncoderPNG();
+        imageDef2 = new ImageDefinition(source2, transformer2, encoder2);
     }
 
     @Test
@@ -68,6 +81,41 @@ void testImageNotCreatedTwice() {
         assertEquals(imageFileBefore.lastModified(), imageFileAfter.lastModified(), "Image was created again.");
     }
 
+    @Test
+    void testImageRecreateOnChange() throws IOException {
+        // Copy file1 to imageDef2File
+        File file1 = new File(getClass().getResource("/testImage.png").getFile());
+        File file2 = new File(getClass().getResource("/logo.png").getFile());
+        assertTrue(file1.exists());
+        assertTrue(file2.exists());
+
+        Files.copy(file1.toPath(), imageDef2File.toPath(), StandardCopyOption.REPLACE_EXISTING);
+
+        var image1 = manager.loadImage(imageDef2);
+        String hash1 = imageDef2.getHashString();
+
+        Files.copy(file2.toPath(), imageDef2File.toPath(), StandardCopyOption.REPLACE_EXISTING);
+
+        var image2 = manager.loadImage(imageDef2);
+        String hash2 = imageDef2.getHashString();
+
+        System.out.println("hash1: " + hash1);
+        System.out.println("hash2: " + hash2);
+        assertNotEquals(hash1, hash2, "changed image file should have different hash");
+
+        File imageFile1 = image1.getFile();
+        File imageFile2 = image2.getFile();
+
+        assertTrue(imageFile1.exists());
+        assertTrue(imageFile2.exists());
+
+        System.out.println("imageFile1: " + imageFile1.lastModified());
+        System.out.println("imageFile2: " + imageFile2.lastModified());
+
+        assertNotEquals(imageFile1.lastModified(), imageFile2.lastModified(),
+                "Image was not created again.");
+    }
+
     @Test
     void testLoadImageFuture() {
         CompletableFuture<ImageResult> future = manager.loadImageFuture(def);