diff --git a/setup.py b/setup.py
index 77b868f..0462010 100644
--- a/setup.py
+++ b/setup.py
@@ -110,5 +110,6 @@ setup(
     long_description="",
     ext_modules=[CMakeExtension("python_rgbcx")],
     cmdclass={"build_ext": CMakeBuild},
+    install_requires=["Pillow"],
     zip_safe=False,
 )
diff --git a/tests/test_rgbcx.py b/tests/test_rgbcx.py
index 6348442..0554cf7 100644
--- a/tests/test_rgbcx.py
+++ b/tests/test_rgbcx.py
@@ -1,29 +1,29 @@
 import unittest
 import python_rgbcx
 import color
+import os
 import s3tc
+from PIL import Image
+
+dir_path = os.path.dirname(os.path.realpath(__file__))
+image_path = dir_path + "/images"
+
+# A block that should always encode greyscale, where every row of pixels is identical, and the left side is lighter than the right side
+greyscale = Image.open(image_path + "/blocks/greyscale.png").tobytes("raw", "RGBX")
+
+# A block that should always encode 3-color when available
+three_color = Image.open(image_path + "/blocks/3color.png").tobytes("raw", "RGBX")
+
+# A block that should always encode 3-color with black when available
+three_color_black = Image.open(image_path + "/blocks/3color black.png").tobytes("raw", "RGBX")
 
 
 class TestBC1Encoder(unittest.TestCase):
     def setUp(self):
-        self.bc1_encoder = python_rgbcx.BC1Encoder(python_rgbcx.InterpolatorType.Ideal, 5)
-        self.bc1_encoder_no3color = python_rgbcx.BC1Encoder(python_rgbcx.InterpolatorType.Ideal, 5, False, False)
-        self.bc1_encoder_noblack = python_rgbcx.BC1Encoder(python_rgbcx.InterpolatorType.Ideal, 5, True, False)
-
-        # A block that should always encode greyscale
-        self.greyscale = b'\x00\x00\x00\xFF\xFF\xFF\xFF\xFF\x55\x55\x55\xFF\xAA\xAA\xAA\xFF' \
-                         b'\x00\x00\x00\xFF\xFF\xFF\xFF\xFF\x55\x55\x55\xFF\xAA\xAA\xAA\xFF' \
-                         b'\x00\x00\x00\xFF\xFF\xFF\xFF\xFF\x55\x55\x55\xFF\xAA\xAA\xAA\xFF' \
-                         b'\x00\x00\x00\xFF\xFF\xFF\xFF\xFF\x55\x55\x55\xFF\xAA\xAA\xAA\xFF'
-
-        # A block that should always encode 3-color with black when available
-        self.chroma_black = b'\x00\x00\x00\xFF\xFF\x00\x00\xFF\x88\x88\x00\xFF\x00\xFF\x00\xFF' \
-                            b'\x00\x00\x00\xFF\xFF\x00\x00\xFF\x88\x88\x00\xFF\x00\xFF\x00\xFF' \
-                            b'\x00\x00\x00\xFF\xFF\x00\x00\xFF\x88\x88\x00\xFF\x00\xFF\x00\xFF' \
-                            b'\x00\x00\x00\xFF\xFF\x00\x00\xFF\x88\x88\x00\xFF\x00\xFF\x00\xFF'
+        self.bc1_encoder = python_rgbcx.BC1Encoder(python_rgbcx.InterpolatorType.Ideal, 5, False, False)
 
     def test_block_size(self):
-        out = self.bc1_encoder.encode_image(self.greyscale, 4, 4)
+        out = self.bc1_encoder.encode_image(greyscale, 4, 4)
 
         self.assertEqual(self.bc1_encoder.block_width, 4, 'incorrect reported block width')
         self.assertEqual(self.bc1_encoder.block_height, 4, 'incorrect reported block height')
@@ -31,20 +31,41 @@ class TestBC1Encoder(unittest.TestCase):
         self.assertEqual(len(out), 8, 'incorrect returned block size')
 
     def test_block_3color(self):
-        out = s3tc.BC1Block.from_bytes(self.bc1_encoder.encode_image(self.chroma_black, 4, 4))
-        out_no_3color = s3tc.BC1Block.from_bytes(self.bc1_encoder_no3color.encode_image(self.chroma_black, 4, 4))
+        out = s3tc.BC1Block.from_bytes(self.bc1_encoder.encode_image(three_color_black, 4, 4))
+
+        self.assertFalse(out.is_3color(), "returned 3 color block with use_3color disabled")
+
+
+class TestBC1Encoder3Color(unittest.TestCase):
+    def setUp(self):
+        self.bc1_encoder = python_rgbcx.BC1Encoder(python_rgbcx.InterpolatorType.Ideal, 5, True, False)
+
+    def test_block_3color(self):
+        out = s3tc.BC1Block.from_bytes(self.bc1_encoder.encode_image(three_color, 4, 4))
+
+        self.assertTrue(out.is_3color(), "returned 4 color block with use_3color enabled")
+
+    def test_block_3color_black(self):
+        out = s3tc.BC1Block.from_bytes(self.bc1_encoder.encode_image(three_color_black, 4, 4))
+
+        self.assertFalse(out.is_3color() and any(3 in row for row in out.selectors),
+                         "returned 3 color block with black pixels with use_3color_black disabled")
+
+
+class TestBC1Encoder3ColorBlack(unittest.TestCase):
+    def setUp(self):
+        self.bc1_encoder = python_rgbcx.BC1Encoder(python_rgbcx.InterpolatorType.Ideal, 5, True, True)
+
+    def test_block_3color(self):
+        out = s3tc.BC1Block.from_bytes(self.bc1_encoder.encode_image(three_color, 4, 4))
 
-        self.assertTrue(out.is_3color(), "incorrect color mode with use_3color enabled")
-        self.assertFalse(out_no_3color.is_3color(), "incorrect color mode with use_3color disabled")
+        self.assertTrue(out.is_3color(), "returned 4 color block with use_3color enabled")
 
-    def test_block_black(self):
-        out = s3tc.BC1Block.from_bytes(self.bc1_encoder.encode_image(self.chroma_black, 4, 4))
-        out_no_black = s3tc.BC1Block.from_bytes(self.bc1_encoder_noblack.encode_image(self.chroma_black, 4, 4))
+    def test_block_3color_black(self):
+        out = s3tc.BC1Block.from_bytes(self.bc1_encoder.encode_image(three_color_black, 4, 4))
 
-        self.assertTrue(any(3 in row for row in out.selectors), "use_3color_black enabled but not used")
-        self.assertFalse(out_no_black.is_3color()
-                         and any(3 in row for row in out_no_black.selectors),
-                         "use_3color_black disabled but 3 color block has black selectors")
+        self.assertTrue(out.is_3color(), "returned 4 color block with use_3color enabled")
+        self.assertTrue(any(3 in row for row in out.selectors), "returned block without black pixels with use_3color_black enabled")
 
 
 if __name__ == '__main__':