diff --git a/tests/circuitpython/_bmp16.py b/tests/circuitpython/_bmp16.py
new file mode 100644
index 0000000000..109e6f2af6
--- /dev/null
+++ b/tests/circuitpython/_bmp16.py
@@ -0,0 +1,53 @@
+import ulab.numpy as np
+import displayio
+import bitmaptools
+
+try:
+    import struct
+except:
+    import ustruct as struct
+
+base_header = b"BMFX\x02\x00\x00\x00\x00\x00F\x00\x00\x008\x00\x00\x00@\x01\x00\x00\xf0\x00\x00\x00\x01\x00\x10\x00\x03\x00\x00\x00\x00X\x02\x00\xd7\r\x00\x00\xd7\r\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\xf8\x00\x00\xe0\x07\x00\x00\x1f\x00\x00\x00\x00\x00\x00\x00"
+
+
+def writebmp16(filename, bitmap):
+    header = bytearray(base_header)
+    header[18:26] = struct.pack("<II", bitmap.width, bitmap.height)
+    with open(filename, "wb") as f:
+        f.write(header)
+        b = np.frombuffer(bitmap, dtype=np.uint16)
+        for i in range(bitmap.height):
+            j = (bitmap.height - i - 1) * bitmap.width
+            f.write(b[j : j + bitmap.width])
+
+
+def loadbmp16(filename, width=320, height=240):
+    """This specialized routine loads 16bpp uncompressed bmp files with a
+    70-byte header. It is not appropriate for generic bmp files."""
+
+    bitmap = displayio.Bitmap(width, height, 65536)
+    with open(filename, "rb") as f:
+        f.seek(70)
+        bitmaptools.readinto(
+            bitmap,
+            f,
+            bits_per_pixel=16,
+            element_size=2,
+            reverse_rows=True,
+        )
+
+    return bitmap
+
+
+if __name__ == "__main__":
+    if "/" in __file__:
+        here = __file__.rsplit("/", 1)[0]
+    else:
+        here = "."
+    b = loadbmp16(here + "/minerva16.bmp")
+    print(b[0, 0])
+    print(b[160, 160])
+    for i, p in enumerate(sorted(set(memoryview(b)))):
+        print("%04x" % p, end="\n" if (i % 8) == 7 else " ")
+    if i % 8 != 7:
+        print()
diff --git a/tests/circuitpython/_loadbmp16.py b/tests/circuitpython/_loadbmp16.py
deleted file mode 100644
index 6d16972de0..0000000000
--- a/tests/circuitpython/_loadbmp16.py
+++ /dev/null
@@ -1,31 +0,0 @@
-import displayio
-import bitmaptools
-
-
-def loadbmp16(filename, width=320, height=240):
-    """This specialized routine loads 16bpp uncompressed bmp files with a
-    70-byte header. It is not appropriate for generic bmp files."""
-
-    bitmap = displayio.Bitmap(width, height, 65536)
-    with open(filename, "rb") as f:
-        f.seek(70)
-        bitmaptools.readinto(
-            bitmap,
-            f,
-            bits_per_pixel=16,
-            element_size=2,
-            swap_bytes_in_element=True,
-            reverse_rows=True,
-        )
-
-    return bitmap
-
-
-if __name__ == "__main__":
-    if "/" in __file__:
-        here = __file__.rsplit("/", 1)[0]
-    else:
-        here = "."
-    b = loadbmp16(here + "/minerva16.bmp")
-    print(b[0, 0])
-    print(b[160, 160])
diff --git a/tests/circuitpython/blend.py b/tests/circuitpython/blend.py
new file mode 100644
index 0000000000..ed940ebf76
--- /dev/null
+++ b/tests/circuitpython/blend.py
@@ -0,0 +1,32 @@
+import bitmaptools
+import displayio
+import _bmp16
+
+if "/" in __file__:
+    here = __file__.rsplit("/", 1)[0]
+else:
+    here = "."
+
+c = displayio.Colorspace.BGR565
+
+b1 = _bmp16.loadbmp16(here + "/minerva16.bmp")
+b2 = _bmp16.loadbmp16(here + "/blinka16.bmp")
+b3 = displayio.Bitmap(320, 240, 65536)
+
+for i in (
+    0,
+    1 / 64,
+    3 / 64,
+    3 / 32,
+    3 / 16,
+    0.5,
+    1 - 3 / 16,
+    1 - 3 / 32,
+    1 - 3 / 64,
+    1 - 1 / 64,
+    1,
+):
+    bitmaptools.alphablend(b3, b1, b2, c, i)
+    _bmp16.writebmp16(f"blend-{i:.2f}.bmp", b3)
+    bitmaptools.alphablend(b3, b1, b2, c, i, 0)
+    _bmp16.writebmp16(f"fade-{i:.2f}.bmp", b3)
diff --git a/tests/circuitpython/dither.py b/tests/circuitpython/dither.py
new file mode 100644
index 0000000000..49a63c458c
--- /dev/null
+++ b/tests/circuitpython/dither.py
@@ -0,0 +1,31 @@
+import bitmaptools
+import displayio
+import _bmp16
+
+if "/" in __file__:
+    here = __file__.rsplit("/", 1)[0]
+else:
+    here = "."
+
+c = displayio.Colorspace.BGR565
+
+b1 = _bmp16.loadbmp16(here + "/minerva16.bmp")
+b3 = displayio.Bitmap(320, 240, 65536)
+
+for i in (
+    0,
+    1 / 64,
+    3 / 64,
+    3 / 32,
+    3 / 16,
+    0.5,
+    1 - 3 / 16,
+    1 - 3 / 32,
+    1 - 3 / 64,
+    1 - 1 / 64,
+    1,
+):
+    bitmaptools.dither(b3, b1, c)
+    _bmp16.writebmp16(f"dither-atkinson.bmp", b3)
+    bitmaptools.dither(b3, b1, c, bitmaptools.DitherAlgorithm.FloydStenberg)
+    _bmp16.writebmp16(f"dither-floydstenberg.bmp", b3)