diff --git a/.gitignore b/.gitignore
index cbfc98e..c65e799 100644
--- a/.gitignore
+++ b/.gitignore
@@ -17,3 +17,4 @@ cover/
 *.c
 *.so
 venv/
+.venv/
diff --git a/.travis.yml b/.travis.yml
deleted file mode 100644
index 2e13fed..0000000
--- a/.travis.yml
+++ /dev/null
@@ -1,21 +0,0 @@
-language: python
-
-python:
-    - "2.7"
-    - "3.5"
-    - "3.6"
-    - "pypy"
-
-install:
-    - if [[ $TRAVIS_PYTHON_VERSION != 'pypy' ]]; then pip install -q Pillow wheezy.captcha; fi
-
-script:
-    - python setup.py -q nosetests
-
-after_success:
-    - pip install coveralls
-    - coverage run --source=captcha setup.py -q nosetests
-    - coveralls
-
-notifications:
-    email: false
diff --git a/MANIFEST.in b/MANIFEST.in
index 90e80fe..613fd93 100644
--- a/MANIFEST.in
+++ b/MANIFEST.in
@@ -1,4 +1,4 @@
 include LICENSE
 include README.rst
-recursive-include captcha/data *.wav
-recursive-include captcha/data *.ttf
+recursive-include src/captcha/data *.wav
+recursive-include src/captcha/data *.ttf
diff --git a/appveyor.yml b/appveyor.yml
deleted file mode 100644
index 0738db0..0000000
--- a/appveyor.yml
+++ /dev/null
@@ -1,16 +0,0 @@
-build: false
-
-environment:
-  matrix:
-    - PYTHON: "C:\\Python27-x64"
-    - PYTHON: "C:\\Python36-x64"
-
-init:
-  - SET PATH=%PYTHON%;%PATH%
-  - python -c "import sys;sys.stdout.write(sys.version)"
-
-install:
-  - python -m pip install nose Pillow wheezy.captcha
-
-test_script:
-  - python -m nose -s
diff --git a/pyproject.toml b/pyproject.toml
new file mode 100644
index 0000000..7819b99
--- /dev/null
+++ b/pyproject.toml
@@ -0,0 +1,70 @@
+[project]
+name = "captcha"
+description = "A captcha library that generates audio and image CAPTCHAs."
+authors = [{name = "Hsiaoming Yang", email="me@lepture.com"}]
+dependencies = [
+  "Pillow",
+]
+license = {text = "BSD-3-Clause"}
+requires-python = ">=3.8"
+dynamic = ["version"]
+readme = "README.rst"
+classifiers = [
+  "Development Status :: 4 - Beta",
+  "Environment :: Console",
+  "Environment :: Web Environment",
+  "Intended Audience :: Developers",
+  "License :: OSI Approved :: BSD License",
+  "Operating System :: OS Independent",
+  "Programming Language :: Python",
+  "Programming Language :: Python :: 3",
+  "Programming Language :: Python :: 3.8",
+  "Programming Language :: Python :: 3.9",
+  "Programming Language :: Python :: 3.10",
+  "Programming Language :: Python :: 3.11",
+  "Programming Language :: Python :: Implementation :: CPython",
+  "Topic :: Security",
+]
+
+[project.urls]
+Documentation = "https://captcha.lepture.com/"
+Source = "https://github.com/lepture/captcha"
+
+[build-system]
+requires = ["setuptools"]
+build-backend = "setuptools.build_meta"
+
+[tool.setuptools.dynamic]
+version = {attr = "captcha.__version__"}
+
+[tool.setuptools.packages.find]
+where = ["src"]
+
+[tool.setuptools.package-data]
+captcha = ["py.typed"]
+
+[tool.pytest.ini_options]
+pythonpath = ["src", "."]
+testpaths = ["tests"]
+filterwarnings = ["error"]
+
+[tool.coverage.run]
+branch = true
+source = ["captcha"]
+
+[tool.coverage.paths]
+source = ["src"]
+
+[tool.coverage.report]
+exclude_lines = [
+  "pragma: no cover",
+  "raise NotImplementedError",
+  "@(abc\\.)?abstractmethod",
+  "@overload",
+]
+
+[tool.mypy]
+python_version = "3.8"
+files = ["src/captcha"]
+show_error_codes = true
+pretty = true
diff --git a/requirements.txt b/requirements.txt
new file mode 100644
index 0000000..026ef54
--- /dev/null
+++ b/requirements.txt
@@ -0,0 +1,5 @@
+Pillow
+types-Pillow
+pytest
+flake8
+mypy
diff --git a/setup.py b/setup.py
index 7c26321..6068493 100644
--- a/setup.py
+++ b/setup.py
@@ -1,61 +1,3 @@
-#!/usr/bin/env python
-# -*- coding: utf-8 -*-
+from setuptools import setup
 
-try:
-    from setuptools import setup
-except ImportError:
-    from distutils.core import setup
-
-import sys
-import captcha
-from email.utils import parseaddr
-
-kwargs = {}
-if not hasattr(sys, 'pypy_version_info'):
-    kwargs['install_requires'] = ['Pillow']
-
-author, author_email = parseaddr(captcha.__author__)
-
-
-def fopen(filename):
-    with open(filename) as f:
-        return f.read()
-
-
-setup(
-    name='captcha',
-    version=captcha.__version__,
-    author=author,
-    author_email=author_email,
-    url=captcha.__homepage__,
-    packages=['captcha'],
-    description='A captcha library that generates audio and image CAPTCHAs.',
-    long_description=fopen('README.rst'),
-    license='BSD',
-    zip_safe=False,
-    include_package_data=True,
-    tests_require=['nose'],
-    test_suite='nose.collector',
-    classifiers=[
-        'Development Status :: 4 - Beta',
-        'Environment :: Console',
-        'Intended Audience :: Developers',
-        'License :: OSI Approved',
-        'License :: OSI Approved :: BSD License',
-        'Operating System :: MacOS',
-        'Operating System :: POSIX',
-        'Operating System :: POSIX :: Linux',
-        'Programming Language :: Python',
-        'Programming Language :: Python :: 2',
-        'Programming Language :: Python :: 2.7',
-        'Programming Language :: Python :: 3',
-        'Programming Language :: Python :: 3.4',
-        'Programming Language :: Python :: 3.5',
-        'Programming Language :: Python :: 3.6',
-        'Programming Language :: Python :: 3.6',
-        'Programming Language :: Python :: Implementation',
-        'Programming Language :: Python :: Implementation :: CPython',
-        'Programming Language :: Python :: Implementation :: PyPy',
-    ],
-    **kwargs
-)
+setup()
diff --git a/captcha/__init__.py b/src/captcha/__init__.py
similarity index 93%
rename from captcha/__init__.py
rename to src/captcha/__init__.py
index 4fe24bd..49927e0 100644
--- a/captcha/__init__.py
+++ b/src/captcha/__init__.py
@@ -10,6 +10,6 @@
     :license: BSD, see LICENSE for more details.
 """
 
-__version__ = '0.4'
+__version__ = '0.5.0'
 __author__ = 'Hsiaoming Yang <me@lepture.com>'
 __homepage__ = 'https://github.com/lepture/captcha'
diff --git a/captcha/audio.py b/src/captcha/audio.py
similarity index 80%
rename from captcha/audio.py
rename to src/captcha/audio.py
index 577f52c..858b2ca 100644
--- a/captcha/audio.py
+++ b/src/captcha/audio.py
@@ -8,17 +8,14 @@
     This module is totally inspired by https://github.com/dchest/captcha
 """
 
+import typing as t
 import os
 import copy
 import wave
 import struct
 import random
 import operator
-
-import sys
-if sys.version_info[0] != 2:
-    import functools
-    reduce = functools.reduce
+from functools import reduce
 
 
 __all__ = ['AudioCaptcha']
@@ -32,14 +29,14 @@ WAVE_HEADER_LENGTH = len(WAVE_HEADER) - 4
 DATA_DIR = os.path.join(os.path.abspath(os.path.dirname(__file__)), 'data')
 
 
-def _read_wave_file(filepath):
+def _read_wave_file(filepath: str) -> bytearray:
     w = wave.open(filepath)
     data = w.readframes(-1)
     w.close()
     return bytearray(data)
 
 
-def change_speed(body, speed=1):
+def change_speed(body: bytearray, speed: float = 1) -> bytearray:
     """Change the voice speed of the wave body."""
     if speed == 1:
         return body
@@ -47,7 +44,7 @@ def change_speed(body, speed=1):
     length = int(len(body) * speed)
     rv = bytearray(length)
 
-    step = 0
+    step: float = 0
     for v in body:
         i = int(step)
         while i < int(step + speed) and i < length:
@@ -57,7 +54,7 @@ def change_speed(body, speed=1):
     return rv
 
 
-def patch_wave_header(body):
+def patch_wave_header(body: bytearray) -> bytearray:
     """Patch header to the given wave body.
 
     :param body: the wave content body, it should be bytearray.
@@ -81,7 +78,7 @@ def patch_wave_header(body):
     return data
 
 
-def create_noise(length, level=4):
+def create_noise(length: int, level: int = 4) -> bytearray:
     """Create white noise for background"""
     noise = bytearray(length)
     adjust = 128 - int(level / 2)
@@ -93,7 +90,7 @@ def create_noise(length, level=4):
     return noise
 
 
-def create_silence(length):
+def create_silence(length: int) -> bytearray:
     """Create a piece of silence."""
     data = bytearray(length)
     i = 0
@@ -103,25 +100,25 @@ def create_silence(length):
     return data
 
 
-def change_sound(body, level=1):
+def change_sound(body: bytearray, level: float = 1) -> bytearray:
     if level == 1:
         return body
 
     body = copy.copy(body)
     for i, v in enumerate(body):
         if v > 128:
-            v = (v - 128) * level + 128
-            v = max(int(v), 128)
+            v = int((v - 128) * level + 128)
+            v = max(v, 128)
             v = min(v, 255)
         elif v < 128:
-            v = 128 - (128 - v) * level
-            v = min(int(v), 128)
+            v = int(128 - (128 - v) * level)
+            v = min(v, 128)
             v = max(v, 0)
         body[i] = v
     return body
 
 
-def mix_wave(src, dst):
+def mix_wave(src: bytearray, dst: bytearray) -> bytearray:
     """Mix two wave body into one."""
     if len(src) > len(dst):
         # output should be longer
@@ -141,7 +138,7 @@ END_BEEP = change_speed(BEEP, 1.4)
 SILENCE = create_silence(int(WAVE_SAMPLE_RATE / 5))
 
 
-class AudioCaptcha(object):
+class AudioCaptcha:
     """Create an audio CAPTCHA.
 
     Create an instance of AudioCaptcha is pretty simple::
@@ -166,16 +163,16 @@ class AudioCaptcha(object):
 
         captcha = AudioCaptcha(voicedir='/path/to/voices')
     """
-    def __init__(self, voicedir=None):
+    def __init__(self, voicedir: t.Optional[str] = None):
         if voicedir is None:
             voicedir = DATA_DIR
 
         self._voicedir = voicedir
-        self._cache = {}
-        self._choices = []
+        self._cache: t.Dict[str, t.List[bytearray]] = {}
+        self._choices: t.List[str] = []
 
     @property
-    def choices(self):
+    def choices(self) -> t.List[str]:
         """Available choices for characters to be generated."""
         if self._choices:
             return self._choices
@@ -184,7 +181,7 @@ class AudioCaptcha(object):
                 self._choices.append(n)
         return self._choices
 
-    def random(self, length=6):
+    def random(self, length: int = 6) -> t.List[str]:
         """Generate a random string with the given length.
 
         :param length: the return string length.
@@ -196,16 +193,16 @@ class AudioCaptcha(object):
         for name in self.choices:
             self._load_data(name)
 
-    def _load_data(self, name):
+    def _load_data(self, name: str):
         dirname = os.path.join(self._voicedir, name)
-        data = []
+        data: t.List[bytearray] = []
         for f in os.listdir(dirname):
             filepath = os.path.join(dirname, f)
             if f.endswith('.wav') and os.path.isfile(filepath):
                 data.append(_read_wave_file(filepath))
         self._cache[name] = data
 
-    def _twist_pick(self, key):
+    def _twist_pick(self, key: str) -> bytearray:
         voice = random.choice(self._cache[key])
 
         # random change speed
@@ -217,7 +214,7 @@ class AudioCaptcha(object):
         voice = change_sound(voice, level)
         return voice
 
-    def _noise_pick(self):
+    def _noise_pick(self) -> bytearray:
         key = random.choice(self.choices)
         voice = random.choice(self._cache[key])
         voice = copy.copy(voice)
@@ -230,7 +227,7 @@ class AudioCaptcha(object):
         voice = change_sound(voice, level)
         return voice
 
-    def create_background_noise(self, length, chars):
+    def create_background_noise(self, length: int, chars: str):
         noise = create_noise(length, 4)
         pos = 0
         while pos < length:
@@ -240,20 +237,20 @@ class AudioCaptcha(object):
             pos = end + random.randint(0, int(WAVE_SAMPLE_RATE / 10))
         return noise
 
-    def create_wave_body(self, chars):
-        voices = []
-        inters = []
-        for key in chars:
-            voices.append(self._twist_pick(key))
-            v = random.randint(WAVE_SAMPLE_RATE, WAVE_SAMPLE_RATE * 3)
-            inters.append(v)
+    def create_wave_body(self, chars: str) -> bytearray:
+        voices: t.List[bytearray] = []
+        inters: t.List[int] = []
+        for c in chars:
+            voices.append(self._twist_pick(c))
+            i = random.randint(WAVE_SAMPLE_RATE, WAVE_SAMPLE_RATE * 3)
+            inters.append(i)
 
         durations = map(lambda a: len(a), voices)
         length = max(durations) * len(chars) + reduce(operator.add, inters)
         bg = self.create_background_noise(length, chars)
 
         # begin
-        pos = inters[0]
+        pos: int = inters[0]
         for i, v in enumerate(voices):
             end = pos + len(v) + 1
             bg[pos:end] = mix_wave(v, bg[pos:end])
@@ -261,7 +258,7 @@ class AudioCaptcha(object):
 
         return BEEP + SILENCE + BEEP + SILENCE + BEEP + bg + END_BEEP
 
-    def generate(self, chars):
+    def generate(self, chars: str) -> bytearray:
         """Generate audio CAPTCHA data. The return data is a bytearray.
 
         :param chars: text to be generated.
@@ -271,7 +268,7 @@ class AudioCaptcha(object):
         body = self.create_wave_body(chars)
         return patch_wave_header(body)
 
-    def write(self, chars, output):
+    def write(self, chars: str, output: str):
         """Generate and write audio CAPTCHA data to the output.
 
         :param chars: text to be generated.
diff --git a/captcha/data/0/default.wav b/src/captcha/data/0/default.wav
similarity index 100%
rename from captcha/data/0/default.wav
rename to src/captcha/data/0/default.wav
diff --git a/captcha/data/1/default.wav b/src/captcha/data/1/default.wav
similarity index 100%
rename from captcha/data/1/default.wav
rename to src/captcha/data/1/default.wav
diff --git a/captcha/data/2/default.wav b/src/captcha/data/2/default.wav
similarity index 100%
rename from captcha/data/2/default.wav
rename to src/captcha/data/2/default.wav
diff --git a/captcha/data/3/default.wav b/src/captcha/data/3/default.wav
similarity index 100%
rename from captcha/data/3/default.wav
rename to src/captcha/data/3/default.wav
diff --git a/captcha/data/4/default.wav b/src/captcha/data/4/default.wav
similarity index 100%
rename from captcha/data/4/default.wav
rename to src/captcha/data/4/default.wav
diff --git a/captcha/data/5/default.wav b/src/captcha/data/5/default.wav
similarity index 100%
rename from captcha/data/5/default.wav
rename to src/captcha/data/5/default.wav
diff --git a/captcha/data/6/default.wav b/src/captcha/data/6/default.wav
similarity index 100%
rename from captcha/data/6/default.wav
rename to src/captcha/data/6/default.wav
diff --git a/captcha/data/7/default.wav b/src/captcha/data/7/default.wav
similarity index 100%
rename from captcha/data/7/default.wav
rename to src/captcha/data/7/default.wav
diff --git a/captcha/data/8/default.wav b/src/captcha/data/8/default.wav
similarity index 100%
rename from captcha/data/8/default.wav
rename to src/captcha/data/8/default.wav
diff --git a/captcha/data/9/default.wav b/src/captcha/data/9/default.wav
similarity index 100%
rename from captcha/data/9/default.wav
rename to src/captcha/data/9/default.wav
diff --git a/captcha/data/DroidSansMono.ttf b/src/captcha/data/DroidSansMono.ttf
similarity index 100%
rename from captcha/data/DroidSansMono.ttf
rename to src/captcha/data/DroidSansMono.ttf
diff --git a/captcha/data/beep.wav b/src/captcha/data/beep.wav
similarity index 100%
rename from captcha/data/beep.wav
rename to src/captcha/data/beep.wav
diff --git a/captcha/image.py b/src/captcha/image.py
similarity index 61%
rename from captcha/image.py
rename to src/captcha/image.py
index 4c5a4de..49c73a2 100644
--- a/captcha/image.py
+++ b/src/captcha/image.py
@@ -8,94 +8,28 @@
 
 import os
 import random
-from PIL import Image
-from PIL import ImageFilter
+import typing as t
+from PIL.Image import new as createImage, Image, QUAD, BILINEAR
 from PIL.ImageDraw import Draw
-from PIL.ImageFont import truetype
-try:
-    from cStringIO import StringIO as BytesIO
-except ImportError:
-    from io import BytesIO
-try:
-    from wheezy.captcha import image as wheezy_captcha
-except ImportError:
-    wheezy_captcha = None
+from PIL.ImageFilter import SMOOTH
+from PIL.ImageFont import FreeTypeFont, truetype
+from io import BytesIO
+
+__all__ = ['ImageCaptcha']
+
+
+ColorTuple = t.Union[t.Tuple[int, int, int], t.Tuple[int, int, int, int]]
 
 DATA_DIR = os.path.join(os.path.abspath(os.path.dirname(__file__)), 'data')
 DEFAULT_FONTS = [os.path.join(DATA_DIR, 'DroidSansMono.ttf')]
 
-if wheezy_captcha:
-    __all__ = ['ImageCaptcha', 'WheezyCaptcha']
-else:
-    __all__ = ['ImageCaptcha']
 
-try:
-    _QUAD = Image.Transform.QUAD
-except AttributeError:
-    _QUAD = Image.QUAD
-
-try:
-    _BILINEAR = Image.Resampling.BILINEAR
-except AttributeError:
-    _BILINEAR = Image.BILINEAR
-
-table  =  []
-for  i  in  range( 256 ):
-    table.append( int(i * 1.97) )
+table: t.List[int] = []
+for i in range(256):
+    table.append(int(i * 1.97))
 
 
-class _Captcha(object):
-    def generate(self, chars, format='png'):
-        """Generate an Image Captcha of the given characters.
-
-        :param chars: text to be generated.
-        :param format: image file format
-        """
-        im = self.generate_image(chars)
-        out = BytesIO()
-        im.save(out, format=format)
-        out.seek(0)
-        return out
-
-    def write(self, chars, output, format='png'):
-        """Generate and write an image CAPTCHA data to the output.
-
-        :param chars: text to be generated.
-        :param output: output destination.
-        :param format: image file format
-        """
-        im = self.generate_image(chars)
-        return im.save(output, format=format)
-
-
-class WheezyCaptcha(_Captcha):
-    """Create an image CAPTCHA with wheezy.captcha."""
-    def __init__(self, width=200, height=75, fonts=None):
-        self._width = width
-        self._height = height
-        self._fonts = fonts or DEFAULT_FONTS
-
-    def generate_image(self, chars):
-        text_drawings = [
-            wheezy_captcha.warp(),
-            wheezy_captcha.rotate(),
-            wheezy_captcha.offset(),
-        ]
-        fn = wheezy_captcha.captcha(
-            drawings=[
-                wheezy_captcha.background(),
-                wheezy_captcha.text(fonts=self._fonts, drawings=text_drawings),
-                wheezy_captcha.curve(),
-                wheezy_captcha.noise(),
-                wheezy_captcha.smooth(),
-            ],
-            width=self._width,
-            height=self._height,
-        )
-        return fn(chars)
-
-
-class ImageCaptcha(_Captcha):
+class ImageCaptcha:
     """Create an image CAPTCHA.
 
     Many of the codes are borrowed from wheezy.captcha, with a modification
@@ -115,26 +49,31 @@ class ImageCaptcha(_Captcha):
     :param fonts: Fonts to be used to generate CAPTCHA images.
     :param font_sizes: Random choose a font size from this parameters.
     """
-    def __init__(self, width=160, height=60, fonts=None, font_sizes=None):
+    def __init__(
+            self,
+            width: int = 160,
+            height: int = 60,
+            fonts: t.Optional[t.List[str]] = None,
+            font_sizes: t.Optional[t.Tuple[int]] = None):
         self._width = width
         self._height = height
         self._fonts = fonts or DEFAULT_FONTS
         self._font_sizes = font_sizes or (42, 50, 56)
-        self._truefonts = []
+        self._truefonts: t.List[FreeTypeFont] = []
 
     @property
-    def truefonts(self):
+    def truefonts(self) -> t.List[FreeTypeFont]:
         if self._truefonts:
             return self._truefonts
-        self._truefonts = tuple([
+        self._truefonts = [
             truetype(n, s)
             for n in self._fonts
             for s in self._font_sizes
-        ])
+        ]
         return self._truefonts
 
     @staticmethod
-    def create_noise_curve(image, color):
+    def create_noise_curve(image: Image, color: ColorTuple):
         w, h = image.size
         x1 = random.randint(0, int(w / 5))
         x2 = random.randint(w - int(w / 5), w)
@@ -147,7 +86,11 @@ class ImageCaptcha(_Captcha):
         return image
 
     @staticmethod
-    def create_noise_dots(image, color, width=3, number=30):
+    def create_noise_dots(
+            image: Image,
+            color: ColorTuple,
+            width: int = 3,
+            number: int = 30) -> Image:
         draw = Draw(image)
         w, h = image.size
         while number:
@@ -157,7 +100,11 @@ class ImageCaptcha(_Captcha):
             number -= 1
         return image
 
-    def create_captcha_image(self, chars, color, background):
+    def create_captcha_image(
+            self,
+            chars: str,
+            color: ColorTuple,
+            background: ColorTuple) -> Image:
         """Create the CAPTCHA image itself.
 
         :param chars: text to be generated.
@@ -166,32 +113,29 @@ class ImageCaptcha(_Captcha):
 
         The color should be a tuple of 3 numbers, such as (0, 255, 255).
         """
-        image = Image.new('RGB', (self._width, self._height), background)
+        image = createImage('RGB', (self._width, self._height), background)
         draw = Draw(image)
 
-        def _draw_character(c):
+        def _draw_character(c: str):
             font = random.choice(self.truefonts)
-            try:
-                _, _, w, h = draw.textbbox((1, 1), c, font=font)
-            except AttributeError:
-                w, h = draw.textsize(c, font=font)
+            _, _, w, h = draw.textbbox((1, 1), c, font=font)
 
-            dx = random.randint(0, 4)
-            dy = random.randint(0, 6)
-            im = Image.new('RGBA', (w + dx, h + dy))
-            Draw(im).text((dx, dy), c, font=font, fill=color)
+            dx1 = random.randint(0, 4)
+            dy1 = random.randint(0, 6)
+            im = createImage('RGBA', (w + dx1, h + dy1))
+            Draw(im).text((dx1, dy1), c, font=font, fill=color)
 
             # rotate
             im = im.crop(im.getbbox())
-            im = im.rotate(random.uniform(-30, 30), _BILINEAR, expand=1)
+            im = im.rotate(random.uniform(-30, 30), BILINEAR, expand=True)
 
             # warp
-            dx = w * random.uniform(0.1, 0.3)
-            dy = h * random.uniform(0.2, 0.3)
-            x1 = int(random.uniform(-dx, dx))
-            y1 = int(random.uniform(-dy, dy))
-            x2 = int(random.uniform(-dx, dx))
-            y2 = int(random.uniform(-dy, dy))
+            dx2 = w * random.uniform(0.1, 0.3)
+            dy2 = h * random.uniform(0.2, 0.3)
+            x1 = int(random.uniform(-dx2, dx2))
+            y1 = int(random.uniform(-dy2, dy2))
+            x2 = int(random.uniform(-dx2, dx2))
+            y2 = int(random.uniform(-dy2, dy2))
             w2 = w + abs(x1) + abs(x2)
             h2 = h + abs(y1) + abs(y2)
             data = (
@@ -201,10 +145,10 @@ class ImageCaptcha(_Captcha):
                 w2 - x2, -y1,
             )
             im = im.resize((w2, h2))
-            im = im.transform((w, h), _QUAD, data)
+            im = im.transform((w, h), QUAD, data)
             return im
 
-        images = []
+        images: t.List[Image] = []
         for c in chars:
             if random.random() > 0.5:
                 images.append(_draw_character(" "))
@@ -230,7 +174,7 @@ class ImageCaptcha(_Captcha):
 
         return image
 
-    def generate_image(self, chars):
+    def generate_image(self, chars: str) -> Image:
         """Generate the image of the given characters.
 
         :param chars: text to be generated.
@@ -240,11 +184,36 @@ class ImageCaptcha(_Captcha):
         im = self.create_captcha_image(chars, color, background)
         self.create_noise_dots(im, color)
         self.create_noise_curve(im, color)
-        im = im.filter(ImageFilter.SMOOTH)
+        im = im.filter(SMOOTH)
         return im
 
+    def generate(self, chars: str, format: str = 'png') -> BytesIO:
+        """Generate an Image Captcha of the given characters.
 
-def random_color(start, end, opacity=None):
+        :param chars: text to be generated.
+        :param format: image file format
+        """
+        im = self.generate_image(chars)
+        out = BytesIO()
+        im.save(out, format=format)
+        out.seek(0)
+        return out
+
+    def write(self, chars: str, output: str, format: str = 'png') -> None:
+        """Generate and write an image CAPTCHA data to the output.
+
+        :param chars: text to be generated.
+        :param output: output destination.
+        :param format: image file format
+        """
+        im = self.generate_image(chars)
+        im.save(output, format=format)
+
+
+def random_color(
+        start: int,
+        end: int,
+        opacity: t.Optional[int]=None) -> ColorTuple:
     red = random.randint(start, end)
     green = random.randint(start, end)
     blue = random.randint(start, end)
diff --git a/tests/test_image.py b/tests/test_image.py
index 3ed6d10..13f7143 100644
--- a/tests/test_image.py
+++ b/tests/test_image.py
@@ -1,15 +1,9 @@
 # coding: utf-8
 
-import sys
+from captcha.image import ImageCaptcha
 
-if not hasattr(sys, 'pypy_version_info'):
-    from captcha.image import ImageCaptcha, WheezyCaptcha
 
-    def test_image_generate():
-        captcha = ImageCaptcha()
-        data = captcha.generate('1234')
-        assert hasattr(data, 'read')
-
-        captcha = WheezyCaptcha()
-        data = captcha.generate('1234')
-        assert hasattr(data, 'read')
+def test_image_generate():
+    captcha = ImageCaptcha()
+    data = captcha.generate('1234')
+    assert hasattr(data, 'read')
diff --git a/tox.ini b/tox.ini
deleted file mode 100644
index 809e8d7..0000000
--- a/tox.ini
+++ /dev/null
@@ -1,13 +0,0 @@
-[tox]
-envlist = py26,py27,py33,py34,pypy
-
-[testenv]
-deps =
-    nose
-    Pillow
-    wheezy.captcha
-commands = nosetests -s
-
-[testenv:pypy]
-deps = nose
-commands = nosetests -s