diff --git a/tests/static/test_image.jpg b/tests/static/test_image.jpg
new file mode 100644
index 0000000..f008aef
Binary files /dev/null and b/tests/static/test_image.jpg differ
diff --git a/tests/test_zebrafy_graphic_field.py b/tests/test_zebrafy_graphic_field.py
index 7a8c0eb..602fbf6 100644
--- a/tests/test_zebrafy_graphic_field.py
+++ b/tests/test_zebrafy_graphic_field.py
@@ -25,6 +25,8 @@
 import unittest
 
 # 2. Known third party imports:
+from PIL import Image
+
 # 3. Local imports in the relative form:
 from zebrafy import GraphicField
 
@@ -70,6 +72,40 @@ def test_graphic_field_deprecated_compression_type(self):
         gfc = GraphicField(self.test_image, compression_type="C")
         self.assertEqual(gfc.format, "Z64")
 
+    def test_get_graphic_field(self):
+        """Test get_graphic_field method."""
+        gf = GraphicField(self.test_image)
+        zpl_string = gf.get_graphic_field()
+        self.assertTrue(zpl_string.startswith("^GFA"))
+
+    def test_get_data_string(self):
+        """Test _get_data_string method."""
+        gf = GraphicField(self.test_image, format="ASCII")
+        data_string = gf._get_data_string()
+        self.assertIsInstance(data_string, str)
+
+        gf = GraphicField(self.test_image, format="B64")
+        data_string = gf._get_data_string()
+        self.assertTrue(data_string.startswith(":B64:"))
+
+        gf = GraphicField(self.test_image, format="Z64")
+        data_string = gf._get_data_string()
+        self.assertTrue(data_string.startswith(":Z64:"))
+
+    def test_edge_cases(self):
+        """Test edge cases with different image sizes and color modes."""
+        small_image = Image.new("1", (1, 1))
+        gf = GraphicField(small_image)
+        self.assertEqual(gf._get_graphic_field_count(), 1)
+
+        large_image = Image.new("1", (1000, 1000))
+        gf = GraphicField(large_image)
+        self.assertEqual(gf._get_graphic_field_count(), 125000)
+
+        color_image = Image.new("RGB", (10, 10))
+        gf = GraphicField(color_image)
+        self.assertEqual(gf._get_graphic_field_count(), 20)
+
 
 if __name__ == "__main__":
     unittest.main()
diff --git a/tests/test_zebrafy_image.py b/tests/test_zebrafy_image.py
index 84ca22d..110c22a 100644
--- a/tests/test_zebrafy_image.py
+++ b/tests/test_zebrafy_image.py
@@ -254,6 +254,29 @@ def test_multiple_image_to_zpl(self):
             complete_zpl, self._read_static_file("test_image_multiple.zpl")
         )
 
+    def test_zebrafy_image_jpeg(self):
+        """Test ZebrafyImage with a JPEG image."""
+        jpeg_image = self._read_static_file("test_image.jpg")
+        zebrafy_image = ZebrafyImage(jpeg_image)
+        self.assertEqual(zebrafy_image.format, "ASCII")
+
+    def test_zebrafy_image_boundary_threshold(self):
+        """Test ZebrafyImage with boundary threshold values."""
+        zebrafy_image = ZebrafyImage(self.test_image)
+        zebrafy_image.threshold = 0
+        self.assertEqual(zebrafy_image.threshold, 0)
+        zebrafy_image.threshold = 255
+        self.assertEqual(zebrafy_image.threshold, 255)
+
+    def test_zebrafy_image_combined_parameters(self):
+        """Test ZebrafyImage with combined parameters."""
+        zebrafy_image = ZebrafyImage(
+            self.test_image, invert=True, dither=False, threshold=100
+        )
+        self.assertTrue(zebrafy_image.invert)
+        self.assertFalse(zebrafy_image.dither)
+        self.assertEqual(zebrafy_image.threshold, 100)
+
 
 if __name__ == "__main__":
     unittest.main()
diff --git a/tests/test_zebrafy_zpl.py b/tests/test_zebrafy_zpl.py
index ff17c57..09668c2 100644
--- a/tests/test_zebrafy_zpl.py
+++ b/tests/test_zebrafy_zpl.py
@@ -121,17 +121,6 @@ def test_z64_zpl_to_pdf(self):
 class TestZebrafyZPLImports(TestZebrafyCommonBase):
     """Test ZebrafyZPL imports."""
 
-    @patch("sys.version_info", (3, 9))
-    def test_imports_python_39_or_higher(self):
-        """Test ZebrafyZPL imports for Python 3.9 or higher."""
-        import importlib
-
-        importlib.reload(sys.modules["zebrafy.zebrafy_zpl"])
-        from zebrafy.zebrafy_zpl import DimensionsType, ToImagesType
-
-        self.assertEqual(DimensionsType, tuple[int, int])
-        self.assertEqual(ToImagesType, list[Image.Image])
-
     @patch("sys.version_info", (3, 8))
     def test_imports_python_38_or_lower(self):
         """Test ZebrafyZPL imports for Python 3.8 or lower."""