diff --git a/color_convert.py b/color_convert.py
index 23aa85c..07a6756 100644
--- a/color_convert.py
+++ b/color_convert.py
@@ -2,7 +2,7 @@ import struct
 import sys
 
 from PIL import Image
-from twiddle import texture as twiddle_texture
+from twiddle import texture as twiddle_texture, npot
 
 class color_format:
     def gbgr1555(r, g, b, a): # nintendo ds
@@ -59,18 +59,19 @@ def convert_indices(palette, pixels):
             d = pixels[i * 4 + 3]
             assert a <= 3 and b <= 3 and c <= 3 and d <= 3, (a, b, c, d)
             pixel = (d << 6) | (c << 4) | (b << 2) | (a << 0)
-            f.write(struct.pack("<B", pixel))
+            assert False, len(palette)
+            yield pixel
     elif len(palette) <= 16:
         for i in range(len(pixels) // 2):
             a = pixels[i * 2 + 0]
             b = pixels[i * 2 + 1]
             assert a <= 15 and b <= 15, (a, b)
             pixel = (b << 4) | (a << 0)
-            f.write(struct.pack("<B", pixel))
+            yield pixel
     elif len(palette) <= 256:
         for pixel in pixels:
             assert pixel <= 255
-            f.write(struct.pack("<B", pixel))
+            yield pixel
     else:
         assert False, len(palette)
 
@@ -82,33 +83,74 @@ def pack_indices(f, indices):
     for value in indices:
         f.write(struct.pack("<B", value))
 
+def mip_levels(n):
+    while True:
+        n = n >> 1
+        yield n
+        if n == 1:
+            break
+
+def generate_mips(im):
+    w, h = im.size
+    assert w == h and npot(w) == w, (w, h)
+    assert w >= 8, (w, h)
+
+    images = [im] + [
+        im.resize(
+            size=(l, l),
+            resample=Image.Resampling.LANCZOS,
+        )
+        for l in mip_levels(w)
+    ]
+
+    return list(reversed(images))
+
+def write_mip(f, mip: Image, is_twiddled: bool, convert):
+    width, height = mip.size
+    print("mip", width, "offset", f"{f.tell():06x}")
+    pixels = list(im.convert("RGBA").getdata())
+    colors = list(convert_colors(convert, pixels))
+    if is_twiddled:
+        new_colors = [0] * width * height
+        max_twiddle_ix = twiddle_texture(new_colors, colors, width, height)
+        assert max_twiddle_ix + 1 == width * height, (max_twiddle_ix, width, height)
+        colors = new_colors[:max_twiddle_ix+1]
+    pack_colors(f, colors)
+
+def write_mips(f, im: Image, is_twiddled: bool, convert):
+    for mip in generate_mips(im):
+        write_mip(f, mip, is_twiddled, convert)
+
 if __name__ == "__main__":
     in_file = sys.argv[1]
     format = sys.argv[2]
     assert sys.argv[3] in {"twiddled", "non_twiddled"}
     is_twiddled = sys.argv[3] == "twiddled"
-    out_file = sys.argv[4]
+    assert sys.argv[4] in {"mipmapped", "non_mipmapped"}
+    is_mipmapped = sys.argv[4] == "mipmapped"
+    out_file = sys.argv[5]
 
     convert = color_format.from_string(format)
 
     with Image.open(in_file) as im:
         width, height = im.size
-        if not im.palette:
-            pixels = list(im.convert("RGBA").getdata())
-            colors = list(convert_colors(convert, pixels))
-            if is_twiddled:
-                new_colors = [0] * len(colors)
-                twiddle_texture(new_colors, colors, width, height)
-                colors = new_colors
+        assert width <= 1024 and height <= 1024, (width, height)
+        assert not im.palette
+        #if not im.palette:
+        if True:
             with open(out_file, 'wb') as f:
-                pack_colors(f, colors)
+                if is_mipmapped:
+                    f.write(bytes([0] * 6))
+                    write_mips(f, im, is_twiddled, convert)
+                else:
+                    write_mip(f, im, is_twiddled, convert)
         else:
             pixels = list(im.convert("P").getdata())
             palette = list(im.palette.colors)
             indices = list(convert_indices(palette, pixels))
             colors = list(convert_colors(convert, [(*c, 255) for c in palette]))
 
-            if twiddle:
+            if is_twiddled:
                 new_indices = [0] * len(indices)
                 twiddle_texture(new_indices, indices, width, height)
                 indices = new_indices
diff --git a/twiddle.py b/twiddle.py
index 1bafdef..7dc9eca 100644
--- a/twiddle.py
+++ b/twiddle.py
@@ -1,5 +1,8 @@
 def log2(n):
     return {
+        1: 0,
+        2: 1,
+        4: 2,
         8: 3,
         16: 4,
         32: 5,
@@ -35,9 +38,24 @@ def from_xy(x, y, width, height):
 
   return twiddle_ix
 
+def npot(v):
+    v -= 1;
+    v |= v >> 1;
+    v |= v >> 2;
+    v |= v >> 4;
+    v |= v >> 8;
+    v |= v >> 16;
+    v += 1;
+    return v
+
 def texture(dst, src, width, height):
+    #pot_height = npot(height)
+    max_twiddle_ix = -1
     for y in range(height):
         for x in range(width):
             twiddle_ix = from_xy(x, y, width, height)
             value = src[y * width + x]
             dst[twiddle_ix] = value
+            if twiddle_ix > max_twiddle_ix:
+                max_twiddle_ix = twiddle_ix
+    return max_twiddle_ix