diff -ur python-webm.orig/webm/encode.py python-webm/webm/encode.py
--- python-webm.orig/webm/encode.py	2012-03-06 16:11:05.000000000 -0700
+++ python-webm/webm/encode.py	2013-10-08 10:25:34.670167613 -0700
@@ -47,23 +47,37 @@
 # -----------------------------------------------------------------------------
 
 # Set argument types
-_LIBRARY.WebPEncodeRGB.argtypes = [c_void_p, c_int, c_int, c_int,
-                                   c_float, c_void_p]
-_LIBRARY.WebPEncodeBGR.argtypes = [c_void_p, c_int, c_int, c_int, c_float,
-                                   c_void_p]
-_LIBRARY.WebPEncodeRGBA.argtypes = [c_void_p, c_int, c_int, c_int, c_float,
-                                    c_void_p]
-_LIBRARY.WebPEncodeBGRA.argtypes = [c_void_p, c_int, c_int, c_int, c_float,
-                                    c_void_p]
-
-# Set return types
-_LIBRARY.WebPEncodeRGB.restype = c_int
-_LIBRARY.WebPEncodeBGR.restype = c_int
-_LIBRARY.WebPEncodeRGBA.restype = c_int
-_LIBRARY.WebPEncodeBGRA.restype = c_int
+LOSSY_ARGS = [c_void_p, c_int, c_int, c_int, c_float, c_void_p]
+_LIBRARY.WebPEncodeRGB.argtypes = LOSSY_ARGS
+_LIBRARY.WebPEncodeBGR.argtypes = LOSSY_ARGS
+_LIBRARY.WebPEncodeRGBA.argtypes = LOSSY_ARGS
+_LIBRARY.WebPEncodeBGRA.argtypes = LOSSY_ARGS
+
+HAS_LOSSLESS = False
+try:
+    LOSSLESS_ARGS = [c_void_p, c_int, c_int, c_int, c_void_p]
+    _LIBRARY.WebPEncodeLosslessRGB.argtypes = LOSSLESS_ARGS 
+    _LIBRARY.WebPEncodeLosslessBGR.argtypes = LOSSLESS_ARGS
+    _LIBRARY.WebPEncodeLosslessRGBA.argtypes = LOSSLESS_ARGS
+    _LIBRARY.WebPEncodeLosslessBGRA.argtypes = LOSSLESS_ARGS
+    
+    # Set return types
+    _LIBRARY.WebPEncodeRGB.restype = c_int
+    _LIBRARY.WebPEncodeBGR.restype = c_int
+    _LIBRARY.WebPEncodeRGBA.restype = c_int
+    _LIBRARY.WebPEncodeBGRA.restype = c_int
+    _LIBRARY.WebPEncodeLosslessRGB.restype = c_int 
+    _LIBRARY.WebPEncodeLosslessBGR.restype = c_int
+    _LIBRARY.WebPEncodeLosslessRGBA.restype = c_int
+    _LIBRARY.WebPEncodeLosslessBGRA.restype = c_int
+
+    HAS_LOSSLESS = True
+except AttributeError:
+    #lossless is missing!
+    pass
 
 
-def _encode(func, image, quality):
+def _lossy(func, image, quality):
     """
     Encode the image with the given quality using the given encoding
     function
@@ -98,6 +112,41 @@
     return WebPHandler(bytearray(output), image.width, image.height)
 
 
+def _lossless(func, image):
+    """
+    Encode the image losslessly using the given encoding
+    function
+
+    :param func: The encoding function
+    :param image: The image to be encoded
+
+    :type function: function
+    :type image: BitmapHandler
+    """
+    assert HAS_LOSSLESS, "this version of the webp library does not support lossless modes!"
+    # Call encode function
+    data = str(image.bitmap)
+    width = c_int(image.width)
+    height = c_int(image.height)
+    stride = c_int(image.stride)
+    output_p = c_void_p()
+
+    size = func(data, width, height, stride, byref(output_p))
+
+    # Check return size
+    if size == 0:
+        raise EncodeError
+
+    # Convert output
+    output = create_string_buffer(size)
+
+    memmove(output, output_p, size)
+
+    return WebPHandler(bytearray(output), image.width, image.height)
+
+
+
+
 # -----------------------------------------------------------------------------
 # Public functions
 # -----------------------------------------------------------------------------
@@ -112,7 +161,7 @@
     :type image: BitmapHandler
     :type quality: float
     """
-    return _encode(_LIBRARY.WebPEncodeRGB, image, quality)
+    return _lossy(_LIBRARY.WebPEncodeRGB, image, quality)
 
 def EncodeRGBA(image, quality=100):
     """
@@ -124,7 +173,7 @@
     :type image: BitmapHandler
     :type quality: float
     """
-    return _encode(_LIBRARY.WebPEncodeRGBA, image, quality)
+    return _lossy(_LIBRARY.WebPEncodeRGBA, image, quality)
 
 def EncodeBGRA(image, quality=100):
     """
@@ -136,7 +185,7 @@
     :type image: BitmapHandler
     :type quality: float
     """
-    return _encode(_LIBRARY.WebPEncodeBGRA, image, quality)
+    return _lossy(_LIBRARY.WebPEncodeBGRA, image, quality)
 
 def EncodeBGR(image, quality=100):
     """
@@ -148,4 +197,45 @@
     :type image: BitmapHandler
     :type quality: float
     """
-    return _encode(_LIBRARY.WebPEncodeBGR, image, quality)
+    return _lossy(_LIBRARY.WebPEncodeBGR, image, quality)
+
+
+def EncodeLosslessRGB(image):
+    """
+    Encode the given RGB image losslessly
+
+    :param image: The RGB image
+
+    :type image: BitmapHandler
+    """
+    return _lossless(_LIBRARY.WebPEncodeLosslessRGB, image)
+
+def EncodeLosslessRGBA(image):
+    """
+    Encode the given RGBA image losslessly
+
+    :param image: The RGBA image
+
+    :type image: BitmapHandler
+    """
+    return _lossless(_LIBRARY.WebPEncodeLosslessRGBA, image)
+
+def EncodeLosslessBGRA(image):
+    """
+    Encode the given BGRA image losslessly
+
+    :param image: The BGRA image
+
+    :type image: BitmapHandler
+    """
+    return _lossless(_LIBRARY.WebPEncodeLosslessBGRA, image)
+
+def EncodeLosslessBGR(image):
+    """
+    Encode the given BGR image losslessly
+
+    :param image: The BGR image
+
+    :type image: BitmapHandler
+    """
+    return _lossless(_LIBRARY.WebPEncodeLosslessBGR, image)