diff --git a/src/PIL/VtfImagePlugin.py b/src/PIL/VtfImagePlugin.py
index 76d8a002e..580c315c6 100644
--- a/src/PIL/VtfImagePlugin.py
+++ b/src/PIL/VtfImagePlugin.py
@@ -188,27 +188,44 @@ def _write_image(fp: BufferedIOBase, im: Image.Image, pixel_format: VtfPF):
     if pixel_format == VtfPF.DXT1:
         encoder = 'bcn'
         encoder_args = (1, "DXT1")
+        im = im.convert('RGB')
+    elif pixel_format == VtfPF.DXT1_ONEBITALPHA:
+        encoder = 'bcn'
+        encoder_args = (1, "DXT1A")
+        im = im.convert('RGBA')
     elif pixel_format == VtfPF.DXT3:
         encoder = 'bcn'
         encoder_args = (3, "DXT3")
+        im = im.convert('RGBA')
     elif pixel_format == VtfPF.DXT5:
         encoder = 'bcn'
         encoder_args = (5, "DXT5")
+        im = im.convert('RGBA')
     elif pixel_format == VtfPF.RGB888:
         encoder = 'raw'
         encoder_args = ("RGB", 0, 0)
+        im = im.convert('RGB')
     elif pixel_format == VtfPF.BGR888:
         encoder = 'raw'
         encoder_args = ("BGR", 0, 0)
+        im = im.convert('RGB')
     elif pixel_format == VtfPF.RGBA8888:
         encoder = 'raw'
         encoder_args = ("RGBA", 0, 0)
+        im = im.convert('RGBA')
+    elif pixel_format == VtfPF.A8:
+        encoder = 'raw'
+        encoder_args = ("L", 0, 0)
+        *_, a = im.split()
+        im = Image.merge('L', (a,))
     elif pixel_format == VtfPF.I8:
         encoder = 'raw'
         encoder_args = ("L", 0, 0)
+        im = im.convert('L')
     elif pixel_format == VtfPF.IA88:
         encoder = 'raw'
         encoder_args = ("LA", 0, 0)
+        im = im.convert('LA')
     elif pixel_format == VtfPF.UV88:
         encoder = 'raw'
         r, g, *_ = im.split()
@@ -316,22 +333,17 @@ def _save(im, fp, filename):
     generate_mips = encoderinfo.get('generate_mips', True)
 
     flags = CompiledVtfFlags(0)
-    if pixel_format in RGBA_FORMATS:
-        im = im.convert('RGBA')
-    if pixel_format in RGB_FORMATS:
-        im = im.convert('RGB')
-    if pixel_format in L_FORMATS:
-        im = im.convert('L')
-    if pixel_format in LA_FORMATS:
-        im = im.convert('LA')
 
-    if "A" in im.mode:
-        if pixel_format == VtfPF.DXT1_ONEBITALPHA:
-            flags |= CompiledVtfFlags.ONEBITALPHA
-        elif pixel_format == VtfPF.DXT1:
-            im = im.convert("RGB")
-        else:
-            flags |= CompiledVtfFlags.EIGHTBITALPHA
+    if pixel_format == VtfPF.DXT1_ONEBITALPHA:
+        flags |= CompiledVtfFlags.ONEBITALPHA
+    elif pixel_format == VtfPF.A8:
+        flags |= CompiledVtfFlags.EIGHTBITALPHA
+    elif pixel_format in RGBA_FORMATS + LA_FORMATS:
+        flags |= CompiledVtfFlags.EIGHTBITALPHA
+    elif pixel_format in RGB_FORMATS + L_FORMATS:
+        pass
+    else:
+        raise VTFException('Unhandled case')
 
     im = im.resize((_closest_power(im.width), _closest_power(im.height)))
     width, height = im.size