Pillow/PIL/Image.py

#
# The Python Imaging Library.
# $Id$
#
# the Image class wrapper
#
# partial release history:
# 1995-09-09 fl   Created
# 1996-03-11 fl   PIL release 0.0 (proof of concept)
# 1996-04-30 fl   PIL release 0.1b1
# 1999-07-28 fl   PIL release 1.0 final
# 2000-06-07 fl   PIL release 1.1
# 2000-10-20 fl   PIL release 1.1.1
# 2001-05-07 fl   PIL release 1.1.2
# 2002-03-15 fl   PIL release 1.1.3
# 2003-05-10 fl   PIL release 1.1.4
# 2005-03-28 fl   PIL release 1.1.5
# 2006-12-02 fl   PIL release 1.1.6
# 2009-11-15 fl   PIL release 1.1.7
#
# Copyright (c) 1997-2009 by Secret Labs AB.  All rights reserved.
# Copyright (c) 1995-2009 by Fredrik Lundh.
#
# See the README file for information on usage and redistribution.
#

from __future__ import print_function

from PIL import VERSION, PILLOW_VERSION, _plugins

import warnings

class _imaging_not_installed:
    # module placeholder
    def __getattr__(self, id):
        raise ImportError("The _imaging C module is not installed")

try:
    # give Tk a chance to set up the environment, in case we're
    # using an _imaging module linked against libtcl/libtk (use
    # __import__ to hide this from naive packagers; we don't really
    # depend on Tk unless ImageTk is used, and that module already
    # imports Tkinter)
    __import__("FixTk")
except ImportError:
    pass

try:
    # If the _imaging C module is not present, you can still use
    # the "open" function to identify files, but you cannot load
    # them.  Note that other modules should not refer to _imaging
    # directly; import Image and use the Image.core variable instead.
    from PIL import _imaging as core
    if PILLOW_VERSION != getattr(core, 'PILLOW_VERSION', None):
         raise ImportError("The _imaging extension was built for another "
                            " version of Pillow or PIL")

except ImportError as v:
    core = _imaging_not_installed()
    # Explanations for ways that we know we might have an import error 
    if str(v).startswith("Module use of python"):
        # The _imaging C module is present, but not compiled for
        # the right version (windows only).  Print a warning, if
        # possible.
        warnings.warn(
            "The _imaging extension was built for another version "
            "of Python.",
            RuntimeWarning
            )
    elif str(v).startswith("The _imaging extension"):
        warnings.warn(str(v), RuntimeWarning)
    elif "Symbol not found: _PyUnicodeUCS2_FromString" in str(v):
        warnings.warn(
            "The _imaging extension was built for Python with UCS2 support; "
            "recompile PIL or build Python --without-wide-unicode. ",
            RuntimeWarning
            )
    elif "Symbol not found: _PyUnicodeUCS4_FromString" in str(v):
        warnings.warn(
            "The _imaging extension was built for Python with UCS4 support; "
            "recompile PIL or build Python --with-wide-unicode. ",
            RuntimeWarning
            )
    # Fail here anyway. Don't let people run with a mostly broken Pillow.     
    raise 

try:
    import builtins
except ImportError:
    import __builtin__
    builtins = __builtin__

from PIL import ImageMode
from PIL._binary import i8, o8
from PIL._util import isPath, isStringType

import os, sys

# type stuff
import collections
import numbers


def isImageType(t):
    """
    Checks if an object is an image object.

    .. warning::

       This function is for internal use only.

    :param t: object to check if it's an image
    :returns: True if the object is an image
    """
    return hasattr(t, "im")

#
# Debug level

DEBUG = 0

#
# Constants (also defined in _imagingmodule.c!)

NONE = 0

# transpose
FLIP_LEFT_RIGHT = 0
FLIP_TOP_BOTTOM = 1
ROTATE_90 = 2
ROTATE_180 = 3
ROTATE_270 = 4

# transforms
AFFINE = 0
EXTENT = 1
PERSPECTIVE = 2
QUAD = 3
MESH = 4

# resampling filters
NONE = 0
NEAREST = 0
ANTIALIAS = 1 # 3-lobed lanczos
LINEAR = BILINEAR = 2
CUBIC = BICUBIC = 3

# dithers
NONE = 0
NEAREST = 0
ORDERED = 1 # Not yet implemented
RASTERIZE = 2 # Not yet implemented
FLOYDSTEINBERG = 3 # default

# palettes/quantizers
WEB = 0
ADAPTIVE = 1

MEDIANCUT = 0
MAXCOVERAGE = 1
FASTOCTREE = 2

# categories
NORMAL = 0
SEQUENCE = 1
CONTAINER = 2

if hasattr(core, 'DEFAULT_STRATEGY'):
    DEFAULT_STRATEGY = core.DEFAULT_STRATEGY
    FILTERED = core.FILTERED
    HUFFMAN_ONLY = core.HUFFMAN_ONLY
    RLE = core.RLE
    FIXED = core.FIXED


# --------------------------------------------------------------------
# Registries

ID = []
OPEN = {}
MIME = {}
SAVE = {}
EXTENSION = {}

# --------------------------------------------------------------------
# Modes supported by this version

_MODEINFO = {
    # NOTE: this table will be removed in future versions.  use
    # getmode* functions or ImageMode descriptors instead.

    # official modes
    "1": ("L", "L", ("1",)),
    "L": ("L", "L", ("L",)),
    "I": ("L", "I", ("I",)),
    "F": ("L", "F", ("F",)),
    "P": ("RGB", "L", ("P",)),
    "RGB": ("RGB", "L", ("R", "G", "B")),
    "RGBX": ("RGB", "L", ("R", "G", "B", "X")),
    "RGBA": ("RGB", "L", ("R", "G", "B", "A")),
    "CMYK": ("RGB", "L", ("C", "M", "Y", "K")),
    "YCbCr": ("RGB", "L", ("Y", "Cb", "Cr")),

    # Experimental modes include I;16, I;16L, I;16B, RGBa, BGR;15, and
    # BGR;24.  Use these modes only if you know exactly what you're
    # doing...

}

if sys.byteorder == 'little':
    _ENDIAN = '<'
else:
    _ENDIAN = '>'

_MODE_CONV = {
    # official modes
    "1": ('|b1', None), # broken
    "L": ('|u1', None),
    "I": (_ENDIAN + 'i4', None),
    "F": (_ENDIAN + 'f4', None),
    "P": ('|u1', None),
    "RGB": ('|u1', 3),
    "RGBX": ('|u1', 4),
    "RGBA": ('|u1', 4),
    "CMYK": ('|u1', 4),
    "YCbCr": ('|u1', 3),
}

def _conv_type_shape(im):
    shape = im.size[1], im.size[0]
    typ, extra = _MODE_CONV[im.mode]
    if extra is None:
        return shape, typ
    else:
        return shape+(extra,), typ


MODES = sorted(_MODEINFO.keys())

# raw modes that may be memory mapped.  NOTE: if you change this, you
# may have to modify the stride calculation in map.c too!
_MAPMODES = ("L", "P", "RGBX", "RGBA", "CMYK", "I;16", "I;16L", "I;16B")


def getmodebase(mode):
    """
    Gets the "base" mode for given mode.  This function returns "L" for
    images that contain grayscale data, and "RGB" for images that
    contain color data.

    :param mode: Input mode.
    :returns: "L" or "RGB".
    :exception KeyError: If the input mode was not a standard mode.
    """
    return ImageMode.getmode(mode).basemode


def getmodetype(mode):
    """
    Gets the storage type mode.  Given a mode, this function returns a
    single-layer mode suitable for storing individual bands.

    :param mode: Input mode.
    :returns: "L", "I", or "F".
    :exception KeyError: If the input mode was not a standard mode.
    """
    return ImageMode.getmode(mode).basetype


def getmodebandnames(mode):
    """
    Gets a list of individual band names.  Given a mode, this function
    returns a tuple containing the names of individual bands (use
    :func:`PIL.Image.getmodetype` to get the mode used to store each individual
    band.

    :param mode: Input mode.
    :returns: A tuple containing band names.  The length of the tuple
        gives the number of bands in an image of the given mode.
    :exception KeyError: If the input mode was not a standard mode.
    """
    return ImageMode.getmode(mode).bands


def getmodebands(mode):
    """
    Gets the number of individual bands for this mode.

    :param mode: Input mode.
    :returns: The number of bands in this mode.
    :exception KeyError: If the input mode was not a standard mode.
    """
    return len(ImageMode.getmode(mode).bands)

# --------------------------------------------------------------------
# Helpers

_initialized = 0


def preinit():
    "Explicitly load standard file format drivers."

    global _initialized
    if _initialized >= 1:
        return

    try:
        from PIL import BmpImagePlugin
    except ImportError:
        pass
    try:
        from PIL import GifImagePlugin
    except ImportError:
        pass
    try:
        from PIL import JpegImagePlugin
    except ImportError:
        pass
    try:
        from PIL import PpmImagePlugin
    except ImportError:
        pass
    try:
        from PIL import PngImagePlugin
    except ImportError:
        pass
#   try:
#       import TiffImagePlugin
#   except ImportError:
#       pass

    _initialized = 1


def init():
    """
    Explicitly initializes the Python Imaging Library. This function
    loads all available file format drivers.
    """

    global _initialized
    if _initialized >= 2:
        return 0

    for plugin in _plugins:
        try:
            if DEBUG:
                print ("Importing %s"%plugin)
            __import__("PIL.%s"%plugin, globals(), locals(), [])
        except ImportError:
            if DEBUG:
                print("Image: failed to import", end=' ')
                print(plugin, ":", sys.exc_info()[1])

    if OPEN or SAVE:
        _initialized = 2
        return 1

# --------------------------------------------------------------------
# Codec factories (used by tobytes/frombytes and ImageFile.load)

def _getdecoder(mode, decoder_name, args, extra=()):

    # tweak arguments
    if args is None:
        args = ()
    elif not isinstance(args, tuple):
        args = (args,)

    try:
        # get decoder
        decoder = getattr(core, decoder_name + "_decoder")
        # print(decoder, mode, args + extra)
        return decoder(mode, *args + extra)
    except AttributeError:
        raise IOError("decoder %s not available" % decoder_name)

def _getencoder(mode, encoder_name, args, extra=()):

    # tweak arguments
    if args is None:
        args = ()
    elif not isinstance(args, tuple):
        args = (args,)

    try:
        # get encoder
        encoder = getattr(core, encoder_name + "_encoder")
        # print(encoder, mode, args + extra)
        return encoder(mode, *args + extra)
    except AttributeError:
        raise IOError("encoder %s not available" % encoder_name)


# --------------------------------------------------------------------
# Simple expression analyzer

def coerce_e(value):
    return value if isinstance(value, _E) else _E(value)

class _E:
    def __init__(self, data):
        self.data = data
    def __add__(self, other):
        return _E((self.data, "__add__", coerce_e(other).data))
    def __mul__(self, other):
        return _E((self.data, "__mul__", coerce_e(other).data))

def _getscaleoffset(expr):
    stub = ["stub"]
    data = expr(_E(stub)).data
    try:
        (a, b, c) = data # simplified syntax
        if (a is stub and b == "__mul__" and isinstance(c, numbers.Number)):
            return c, 0.0
        if (a is stub and b == "__add__" and isinstance(c, numbers.Number)):
            return 1.0, c
    except TypeError: pass
    try:
        ((a, b, c), d, e) = data # full syntax
        if (a is stub and b == "__mul__" and isinstance(c, numbers.Number) and
            d == "__add__" and isinstance(e, numbers.Number)):
            return c, e
    except TypeError: pass
    raise ValueError("illegal expression")


# --------------------------------------------------------------------
# Implementation wrapper

class Image:
    """
    This class represents an image object.  To create Image objects, use
    the appropriate factory functions.  There's hardly ever any reason
    to call the Image constructor directly.

    * :func:`PIL.Image.open`
    * :func:`PIL.Image.new`
    * :func:`PIL.Image.frombytes`
    """
    format = None
    format_description = None

    def __init__(self):
        # FIXME: take "new" parameters / other image?
        # FIXME: turn mode and size into delegating properties?
        self.im = None
        self.mode = ""
        self.size = (0, 0)
        self.palette = None
        self.info = {}
        self.category = NORMAL
        self.readonly = 0

    def _new(self, im):
        new = Image()
        new.im = im
        new.mode = im.mode
        new.size = im.size
        new.palette = self.palette
        if im.mode == "P":
            from PIL import ImagePalette
            new.palette = ImagePalette.ImagePalette()
        try:
            new.info = self.info.copy()
        except AttributeError:
            # fallback (pre-1.5.2)
            new.info = {}
            for k, v in self.info:
                new.info[k] = v
        return new

    _makeself = _new # compatibility

    def _copy(self):
        self.load()
        self.im = self.im.copy()
        self.readonly = 0

    def _dump(self, file=None, format=None):
        import tempfile
        if not file:
            file = tempfile.mktemp()
        self.load()
        if not format or format == "PPM":
            self.im.save_ppm(file)
        else:
            file = file + "." + format
            self.save(file, format)
        return file

    def __repr__(self):
        return "<%s.%s image mode=%s size=%dx%d at 0x%X>" % (
            self.__class__.__module__, self.__class__.__name__,
            self.mode, self.size[0], self.size[1],
            id(self)
            )

    def __getattr__(self, name):
        if name == "__array_interface__":
            # numpy array interface support
            new = {}
            shape, typestr = _conv_type_shape(self)
            new['shape'] = shape
            new['typestr'] = typestr
            new['data'] = self.tobytes()
            return new
        raise AttributeError(name)

    def tobytes(self, encoder_name="raw", *args):
        """
        Return image as a bytes object

        :param encoder_name: What encoder to use.  The default is to
                             use the standard "raw" encoder.
        :param args: Extra arguments to the encoder.
        :rtype: A bytes object.
        """

        # may pass tuple instead of argument list
        if len(args) == 1 and isinstance(args[0], tuple):
            args = args[0]

        if encoder_name == "raw" and args == ():
            args = self.mode

        self.load()

        # unpack data
        e = _getencoder(self.mode, encoder_name, args)
        e.setimage(self.im)

        bufsize = max(65536, self.size[0] * 4) # see RawEncode.c

        data = []
        while True:
            l, s, d = e.encode(bufsize)
            data.append(d)
            if s:
                break
        if s < 0:
            raise RuntimeError("encoder error %d in tobytes" % s)

        return b"".join(data)

    # Declare tostring as alias to tobytes
    def tostring(self, *args, **kw):
        warnings.warn(
            'tostring() is deprecated. Please call tobytes() instead.',
            DeprecationWarning,
            stacklevel=2,
        )
        return self.tobytes(*args, **kw)

    def tobitmap(self, name="image"):
        """
        Returns the image converted to an X11 bitmap.

        .. note:: This method only works for mode "1" images.

        :param name: The name prefix to use for the bitmap variables.
        :returns: A string containing an X11 bitmap.
        :raises ValueError: If the mode is not "1"
        """

        self.load()
        if self.mode != "1":
            raise ValueError("not a bitmap")
        data = self.tobytes("xbm")
        return b"".join([("#define %s_width %d\n" % (name, self.size[0])).encode('ascii'),
                ("#define %s_height %d\n"% (name, self.size[1])).encode('ascii'),
                ("static char %s_bits[] = {\n" % name).encode('ascii'), data, b"};"])

    def frombytes(self, data, decoder_name="raw", *args):
        """
        Loads this image with pixel data from a bytes object.

        This method is similar to the :func:`PIL.Image.frombytes` function, but
        loads data into this image instead of creating a new image object.
        """

        # may pass tuple instead of argument list
        if len(args) == 1 and isinstance(args[0], tuple):
            args = args[0]

        # default format
        if decoder_name == "raw" and args == ():
            args = self.mode

        # unpack data
        d = _getdecoder(self.mode, decoder_name, args)
        d.setimage(self.im)
        s = d.decode(data)

        if s[0] >= 0:
            raise ValueError("not enough image data")
        if s[1] != 0:
            raise ValueError("cannot decode image data")

    def fromstring(self, *args, **kw):
        """ Deprecated alias to frombytes """
        warnings.warn('fromstring() is deprecated. Please call frombytes() instead.', DeprecationWarning)
        return self.frombytes(*args, **kw)

    def load(self):
        """
        Allocates storage for the image and loads the pixel data.  In
        normal cases, you don't need to call this method, since the
        Image class automatically loads an opened image when it is
        accessed for the first time.

        :returns: An image access object.
        """
        if self.im and self.palette and self.palette.dirty:
            # realize palette
            self.im.putpalette(*self.palette.getdata())
            self.palette.dirty = 0
            self.palette.mode = "RGB"
            self.palette.rawmode = None
            if "transparency" in self.info:
                if isinstance(self.info["transparency"], int):
                    self.im.putpalettealpha(self.info["transparency"], 0)
                else:
                    self.im.putpalettealphas(self.info["transparency"])
                self.palette.mode = "RGBA"

        if self.im:
            return self.im.pixel_access(self.readonly)

    def verify(self):
        """
        Verifies the contents of a file. For data read from a file, this
        method attempts to determine if the file is broken, without
        actually decoding the image data.  If this method finds any
        problems, it raises suitable exceptions.  If you need to load
        the image after using this method, you must reopen the image
        file.
        """
        pass

    def convert(self, mode=None, data=None, dither=None,
                palette=WEB, colors=256):
        """
        Returns a converted copy of this image. For the "P" mode, this
        method translates pixels through the palette.  If mode is
        omitted, a mode is chosen so that all information in the image
        and the palette can be represented without a palette.

        The current version supports all possible conversions between
        "L", "RGB" and "CMYK."

        When translating a colour image to black and white (mode "L"),
        the library uses the ITU-R 601-2 luma transform:

            L = R * 299/1000 + G * 587/1000 + B * 114/1000

        When translating a greyscale image into a bilevel image (mode
        "1"), all non-zero values are set to 255 (white). To use other
        thresholds, use the :func:`PIL.Image.Image.point` method.

        :param mode: The requested mode.
        :param matrix: An optional conversion matrix.  If given, this
           should be 4- or 16-tuple containing floating point values.
        :param dither: Dithering method, used when converting from
           mode "RGB" to "P".
           Available methods are NONE or FLOYDSTEINBERG (default).
        :param palette: Palette to use when converting from mode "RGB"
           to "P".  Available palettes are WEB or ADAPTIVE.
        :param colors: Number of colors to use for the ADAPTIVE palette.
           Defaults to 256.
        :rtype: :class:`PIL.Image.Image`
        :returns: An Image object.
        """

        if not mode:
            # determine default mode
            if self.mode == "P":
                self.load()
                if self.palette:
                    mode = self.palette.mode
                else:
                    mode = "RGB"
            else:
                return self.copy()

        self.load()

        if data:
            # matrix conversion
            if mode not in ("L", "RGB"):
                raise ValueError("illegal conversion")
            im = self.im.convert_matrix(mode, data)
            return self._new(im)

        if mode == "P" and palette == ADAPTIVE:
            im = self.im.quantize(colors)
            return self._new(im)

        # colourspace conversion
        if dither is None:
            dither = FLOYDSTEINBERG

        # fake a P-mode image, otherwise the transparency will get lost as there is
        # currently no other way to convert transparency into an RGBA image
        if self.mode == "L" and mode == "RGBA" and "transparency" in self.info:
            from PIL import ImagePalette
            self.mode = "P"
            bytePalette = bytes(bytearray([i//3 for i in range(768)]))
            self.palette = ImagePalette.raw("RGB", bytePalette)
            self.palette.dirty = 1
            self.load()

        try:
            im = self.im.convert(mode, dither)
        except ValueError:
            try:
                # normalize source image and try again
                im = self.im.convert(getmodebase(self.mode))
                im = im.convert(mode, dither)
            except KeyError:
                raise ValueError("illegal conversion")

        return self._new(im)

    def quantize(self, colors=256, method=0, kmeans=0, palette=None):

        # methods:
        #    0 = median cut
        #    1 = maximum coverage
        #    2 = fast octree

        # NOTE: this functionality will be moved to the extended
        # quantizer interface in a later version of PIL.

        self.load()

        if palette:
            # use palette from reference image
            palette.load()
            if palette.mode != "P":
                raise ValueError("bad mode for palette image")
            if self.mode != "RGB" and self.mode != "L":
                raise ValueError(
                    "only RGB or L mode images can be quantized to a palette"
                    )
            im = self.im.convert("P", 1, palette.im)
            return self._makeself(im)

        im = self.im.quantize(colors, method, kmeans)
        return self._new(im)

    def copy(self):
        """
        Copies this image. Use this method if you wish to paste things
        into an image, but still retain the original.

        :rtype: :class:`PIL.Image.Image`
        :returns: An Image object.
        """
        self.load()
        im = self.im.copy()
        return self._new(im)

    def crop(self, box=None):
        """
        Returns a rectangular region from this image. The box is a
        4-tuple defining the left, upper, right, and lower pixel
        coordinate.

        This is a lazy operation.  Changes to the source image may or
        may not be reflected in the cropped image.  To break the
        connection, call the {@link #Image.load} method on the cropped
        copy.

        :param box: The crop rectangle, as a (left, upper, right, lower)-tuple.
        :rtype: :class:`PIL.Image.Image`
        :returns: An Image object.
        """

        self.load()
        if box is None:
            return self.copy()

        # lazy operation
        return _ImageCrop(self, box)

    def draft(self, mode, size):
        """
        Configures the image file loader so it returns a version of the
        image that as closely as possible matches the given mode and
        size.  For example, you can use this method to convert a colour
        JPEG to greyscale while loading it, or to extract a 128x192
        version from a PCD file.

        Note that this method modifies the Image object in place.  If
        the image has already been loaded, this method has no effect.

        :param mode: The requested mode.
        :param size: The requested size.
        """
        pass

    def _expand(self, xmargin, ymargin=None):
        if ymargin is None:
            ymargin = xmargin
        self.load()
        return self._new(self.im.expand(xmargin, ymargin, 0))

    def filter(self, filter):
        """
        Filters this image using the given filter.  For a list of
        available filters, see the :mod:`PIL.ImageFilter` module.

        :param filter: Filter kernel.
        :returns: An Image object.
        """

        self.load()

        if isinstance(filter, collections.Callable):
            filter = filter()
        if not hasattr(filter, "filter"):
            raise TypeError("filter argument should be ImageFilter.Filter instance or class")

        if self.im.bands == 1:
            return self._new(filter.filter(self.im))
        # fix to handle multiband images since _imaging doesn't
        ims = []
        for c in range(self.im.bands):
            ims.append(self._new(filter.filter(self.im.getband(c))))
        return merge(self.mode, ims)

    def getbands(self):
        """
        Returns a tuple containing the name of each band in this image.
        For example, **getbands** on an RGB image returns ("R", "G", "B").

        :returns: A tuple containing band names.
        :rtype: tuple
        """
        return ImageMode.getmode(self.mode).bands

    def getbbox(self):
        """
        Calculates the bounding box of the non-zero regions in the
        image.

        :returns: The bounding box is returned as a 4-tuple defining the
           left, upper, right, and lower pixel coordinate. If the image
           is completely empty, this method returns None.

        """

        self.load()
        return self.im.getbbox()

    def getcolors(self, maxcolors=256):
        """
        Returns a list of colors used in this image.

        :param maxcolors: Maximum number of colors.  If this number is
           exceeded, this method returns None.  The default limit is
           256 colors.
        :returns: An unsorted list of (count, pixel) values.
        """

        self.load()
        if self.mode in ("1", "L", "P"):
            h = self.im.histogram()
            out = []
            for i in range(256):
                if h[i]:
                    out.append((h[i], i))
            if len(out) > maxcolors:
                return None
            return out
        return self.im.getcolors(maxcolors)

    def getdata(self, band = None):
        """
        Returns the contents of this image as a sequence object
        containing pixel values.  The sequence object is flattened, so
        that values for line one follow directly after the values of
        line zero, and so on.

        Note that the sequence object returned by this method is an
        internal PIL data type, which only supports certain sequence
        operations.  To convert it to an ordinary sequence (e.g. for
        printing), use **list(im.getdata())**.

        :param band: What band to return.  The default is to return
           all bands.  To return a single band, pass in the index
           value (e.g. 0 to get the "R" band from an "RGB" image).
        :returns: A sequence-like object.
        """

        self.load()
        if band is not None:
            return self.im.getband(band)
        return self.im # could be abused

    def getextrema(self):
        """
        Gets the the minimum and maximum pixel values for each band in
        the image.

        :returns: For a single-band image, a 2-tuple containing the
           minimum and maximum pixel value.  For a multi-band image,
           a tuple containing one 2-tuple for each band.
        """

        self.load()
        if self.im.bands > 1:
            extrema = []
            for i in range(self.im.bands):
                extrema.append(self.im.getband(i).getextrema())
            return tuple(extrema)
        return self.im.getextrema()

    def getim(self):
        """
        Returns a capsule that points to the internal image memory.

        :returns: A capsule object.
        """

        self.load()
        return self.im.ptr


    def getpalette(self):
        """
        Returns the image palette as a list.

        :returns: A list of color values [r, g, b, ...], or None if the
           image has no palette.
        """

        self.load()
        try:
            if bytes is str:
                return [i8(c) for c in self.im.getpalette()]
            else:
                return list(self.im.getpalette())
        except ValueError:
            return None # no palette


    def getpixel(self, xy):
        """
        Returns the pixel value at a given position.

        :param xy: The coordinate, given as (x, y).
        :returns: The pixel value.  If the image is a multi-layer image,
           this method returns a tuple.
        """

        self.load()
        return self.im.getpixel(xy)

    def getprojection(self):
        """
        Get projection to x and y axes

        :returns: Two sequences, indicating where there are non-zero
            pixels along the X-axis and the Y-axis, respectively.
        """

        self.load()
        x, y = self.im.getprojection()
        return [i8(c) for c in x], [i8(c) for c in y]

    def histogram(self, mask=None, extrema=None):
        """
        Returns a histogram for the image. The histogram is returned as
        a list of pixel counts, one for each pixel value in the source
        image. If the image has more than one band, the histograms for
        all bands are concatenated (for example, the histogram for an
        "RGB" image contains 768 values).

        A bilevel image (mode "1") is treated as a greyscale ("L") image
        by this method.

        If a mask is provided, the method returns a histogram for those
        parts of the image where the mask image is non-zero. The mask
        image must have the same size as the image, and be either a
        bi-level image (mode "1") or a greyscale image ("L").

        :param mask: An optional mask.
        :returns: A list containing pixel counts.
        """
        self.load()
        if mask:
            mask.load()
            return self.im.histogram((0, 0), mask.im)
        if self.mode in ("I", "F"):
            if extrema is None:
                extrema = self.getextrema()
            return self.im.histogram(extrema)
        return self.im.histogram()

    def offset(self, xoffset, yoffset=None):
        """
        (Deprecated) Returns a copy of the image where the data has been
        offset by the given distances. Data wraps around the edges. If
        yoffset is omitted, it is assumed to be equal to xoffset.

        This method is deprecated. New code should use the
        :func:`PIL.ImageChops.offset` function in the
        :mod:`PIL.ImageChops` module.

        :param xoffset: The horizontal distance.
        :param yoffset: The vertical distance.  If omitted, both
           distances are set to the same value.
        :returns: An Image object.
        """
        if warnings:
            warnings.warn(
                "'offset' is deprecated; use 'ImageChops.offset' instead",
                DeprecationWarning, stacklevel=2
                )
        from PIL import ImageChops
        return ImageChops.offset(self, xoffset, yoffset)

    def paste(self, im, box=None, mask=None):
        """
        Pastes another image into this image. The box argument is either
        a 2-tuple giving the upper left corner, a 4-tuple defining the
        left, upper, right, and lower pixel coordinate, or None (same as
        (0, 0)).  If a 4-tuple is given, the size of the pasted image
        must match the size of the region.

        If the modes don't match, the pasted image is converted to the
        mode of this image (see the :func:`PIL.Image.Image.convert` method for
        details).

        Instead of an image, the source can be a integer or tuple
        containing pixel values.  The method then fills the region
        with the given colour.  When creating RGB images, you can
        also use colour strings as supported by the ImageColor module.

        If a mask is given, this method updates only the regions
        indicated by the mask.  You can use either "1", "L" or "RGBA"
        images (in the latter case, the alpha band is used as mask).
        Where the mask is 255, the given image is copied as is.  Where
        the mask is 0, the current value is preserved.  Intermediate
        values can be used for transparency effects.

        Note that if you paste an "RGBA" image, the alpha band is
        ignored.  You can work around this by using the same image as
        both source image and mask.

        :param im: Source image or pixel value (integer or tuple).
        :param box: An optional 4-tuple giving the region to paste into.
           If a 2-tuple is used instead, it's treated as the upper left
           corner.  If omitted or None, the source is pasted into the
           upper left corner.

           If an image is given as the second argument and there is no
           third, the box defaults to (0, 0), and the second argument
           is interpreted as a mask image.
        :param mask: An optional mask image.
        :returns: An Image object.
        """

        if isImageType(box) and mask is None:
            # abbreviated paste(im, mask) syntax
            mask = box; box = None

        if box is None:
            # cover all of self
            box = (0, 0) + self.size

        if len(box) == 2:
            # lower left corner given; get size from image or mask
            if isImageType(im):
                size = im.size
            elif isImageType(mask):
                size = mask.size
            else:
                # FIXME: use self.size here?
                raise ValueError(
                    "cannot determine region size; use 4-item box"
                    )
            box = box + (box[0]+size[0], box[1]+size[1])

        if isStringType(im):
            from PIL import ImageColor
            im = ImageColor.getcolor(im, self.mode)

        elif isImageType(im):
            im.load()
            if self.mode != im.mode:
                if self.mode != "RGB" or im.mode not in ("RGBA", "RGBa"):
                    # should use an adapter for this!
                    im = im.convert(self.mode)
            im = im.im

        self.load()
        if self.readonly:
            self._copy()

        if mask:
            mask.load()
            self.im.paste(im, box, mask.im)
        else:
            self.im.paste(im, box)

    def point(self, lut, mode=None):
        """
        Maps this image through a lookup table or function.

        :param lut: A lookup table, containing 256 values per band in the
           image. A function can be used instead, it should take a single
           argument. The function is called once for each possible pixel
           value, and the resulting table is applied to all bands of the
           image.
        :param mode: Output mode (default is same as input).  In the
           current version, this can only be used if the source image
           has mode "L" or "P", and the output has mode "1".
        :returns: An Image object.
        """

        self.load()

        if isinstance(lut, ImagePointHandler):
            return lut.point(self)

        if not isinstance(lut, collections.Sequence):
            # if it isn't a list, it should be a function
            if self.mode in ("I", "I;16", "F"):
                # check if the function can be used with point_transform
                scale, offset = _getscaleoffset(lut)
                return self._new(self.im.point_transform(scale, offset))
            # for other modes, convert the function to a table
            lut = [lut(i) for i in range(256)] * self.im.bands

        if self.mode == "F":
            # FIXME: _imaging returns a confusing error message for this case
            raise ValueError("point operation not supported for this mode")

        return self._new(self.im.point(lut, mode))

    def putalpha(self, alpha):
        """
        Adds or replaces the alpha layer in this image.  If the image
        does not have an alpha layer, it's converted to "LA" or "RGBA".
        The new layer must be either "L" or "1".

        :param alpha: The new alpha layer.  This can either be an "L" or "1"
           image having the same size as this image, or an integer or
           other color value.
        """

        self.load()
        if self.readonly:
            self._copy()

        if self.mode not in ("LA", "RGBA"):
            # attempt to promote self to a matching alpha mode
            try:
                mode = getmodebase(self.mode) + "A"
                try:
                    self.im.setmode(mode)
                except (AttributeError, ValueError):
                    # do things the hard way
                    im = self.im.convert(mode)
                    if im.mode not in ("LA", "RGBA"):
                        raise ValueError # sanity check
                    self.im = im
                self.mode = self.im.mode
            except (KeyError, ValueError):
                raise ValueError("illegal image mode")

        if self.mode == "LA":
            band = 1
        else:
            band = 3

        if isImageType(alpha):
            # alpha layer
            if alpha.mode not in ("1", "L"):
                raise ValueError("illegal image mode")
            alpha.load()
            if alpha.mode == "1":
                alpha = alpha.convert("L")
        else:
            # constant alpha
            try:
                self.im.fillband(band, alpha)
            except (AttributeError, ValueError):
                # do things the hard way
                alpha = new("L", self.size, alpha)
            else:
                return

        self.im.putband(alpha.im, band)

    def putdata(self, data, scale=1.0, offset=0.0):
        """
        Copies pixel data to this image.  This method copies data from a
        sequence object into the image, starting at the upper left
        corner (0, 0), and continuing until either the image or the
        sequence ends.  The scale and offset values are used to adjust
        the sequence values: **pixel = value*scale + offset**.

        :param data: A sequence object.
        :param scale: An optional scale value.  The default is 1.0.
        :param offset: An optional offset value.  The default is 0.0.
        """

        self.load()
        if self.readonly:
            self._copy()

        self.im.putdata(data, scale, offset)

    def putpalette(self, data, rawmode="RGB"):
        """
        Attaches a palette to this image.  The image must be a "P" or
        "L" image, and the palette sequence must contain 768 integer
        values, where each group of three values represent the red,
        green, and blue values for the corresponding pixel
        index. Instead of an integer sequence, you can use an 8-bit
        string.

        :param data: A palette sequence (either a list or a string).
        """
        from PIL import ImagePalette

        if self.mode not in ("L", "P"):
            raise ValueError("illegal image mode")
        self.load()
        if isinstance(data, ImagePalette.ImagePalette):
            palette = ImagePalette.raw(data.rawmode, data.palette)
        else:
            if not isinstance(data, bytes):
                if bytes is str:
                    data = "".join(chr(x) for x in data)
                else:
                    data = bytes(data)
            palette = ImagePalette.raw(rawmode, data)
        self.mode = "P"
        self.palette = palette
        self.palette.mode = "RGB"
        self.load() # install new palette

    def putpixel(self, xy, value):
        """
        Modifies the pixel at the given position. The colour is given as
        a single numerical value for single-band images, and a tuple for
        multi-band images.

        Note that this method is relatively slow.  For more extensive
        changes, use :func:`PIL.Image.Image.paste` or the :mod:`PIL.ImageDraw`
        module instead.

        See:

        * :func:`PIL.Image.Image.paste`
        * :func:`PIL.Image.Image.putdata`
        * :mod:`PIL.ImageDraw`

        :param xy: The pixel coordinate, given as (x, y).
        :param value: The pixel value.
        """

        self.load()
        if self.readonly:
            self._copy()

        return self.im.putpixel(xy, value)

    def resize(self, size, resample=NEAREST):
        """
        Returns a resized copy of this image.

        :param size: The requested size in pixels, as a 2-tuple:
           (width, height).
        :param filter: An optional resampling filter.  This can be
           one of :attr:`PIL.Image.NEAREST` (use nearest neighbour),
           :attr:`PIL.Image.BILINEAR` (linear interpolation in a 2x2
           environment), :attr:`PIL.Image.BICUBIC` (cubic spline
           interpolation in a 4x4 environment), or
           :attr:`PIL.Image.ANTIALIAS` (a high-quality downsampling filter).
           If omitted, or if the image has mode "1" or "P", it is
           set :attr:`PIL.Image.NEAREST`.
        :returns: An Image object.
        """

        if resample not in (NEAREST, BILINEAR, BICUBIC, ANTIALIAS):
            raise ValueError("unknown resampling filter")

        self.load()

        if self.mode in ("1", "P"):
            resample = NEAREST

        if resample == ANTIALIAS:
            # requires stretch support (imToolkit & PIL 1.1.3)
            try:
                im = self.im.stretch(size, resample)
            except AttributeError:
                raise ValueError("unsupported resampling filter")
        else:
            im = self.im.resize(size, resample)

        return self._new(im)

    def rotate(self, angle, resample=NEAREST, expand=0):
        """
        Returns a rotated copy of this image.  This method returns a
        copy of this image, rotated the given number of degrees counter
        clockwise around its centre.

        :param angle: In degrees counter clockwise.
        :param filter: An optional resampling filter.  This can be
           one of :attr:`PIL.Image.NEAREST` (use nearest neighbour),
           :attr:`PIL.Image.BILINEAR` (linear interpolation in a 2x2
           environment), or :attr:`PIL.Image.BICUBIC`
           (cubic spline interpolation in a 4x4 environment).
           If omitted, or if the image has mode "1" or "P", it is
           set :attr:`PIL.Image.NEAREST`.
        :param expand: Optional expansion flag.  If true, expands the output
           image to make it large enough to hold the entire rotated image.
           If false or omitted, make the output image the same size as the
           input image.
        :returns: An Image object.
        """

        if expand:
            import math
            angle = -angle * math.pi / 180
            matrix = [
                 math.cos(angle), math.sin(angle), 0.0,
                -math.sin(angle), math.cos(angle), 0.0
                 ]
            def transform(x, y, matrix=matrix):
                (a, b, c, d, e, f) = matrix
                return a*x + b*y + c, d*x + e*y + f

            # calculate output size
            w, h = self.size
            xx = []
            yy = []
            for x, y in ((0, 0), (w, 0), (w, h), (0, h)):
                x, y = transform(x, y)
                xx.append(x)
                yy.append(y)
            w = int(math.ceil(max(xx)) - math.floor(min(xx)))
            h = int(math.ceil(max(yy)) - math.floor(min(yy)))

            # adjust center
            x, y = transform(w / 2.0, h / 2.0)
            matrix[2] = self.size[0] / 2.0 - x
            matrix[5] = self.size[1] / 2.0 - y

            return self.transform((w, h), AFFINE, matrix, resample)

        if resample not in (NEAREST, BILINEAR, BICUBIC):
            raise ValueError("unknown resampling filter")

        self.load()

        if self.mode in ("1", "P"):
            resample = NEAREST

        return self._new(self.im.rotate(angle, resample))

    def save(self, fp, format=None, **params):
        """
        Saves this image under the given filename.  If no format is
        specified, the format to use is determined from the filename
        extension, if possible.

        Keyword options can be used to provide additional instructions
        to the writer. If a writer doesn't recognise an option, it is
        silently ignored. The available options are described later in
        this handbook.

        You can use a file object instead of a filename. In this case,
        you must always specify the format. The file object must
        implement the **seek**, **tell**, and **write**
        methods, and be opened in binary mode.

        :param file: File name or file object.
        :param format: Optional format override.  If omitted, the
           format to use is determined from the filename extension.
           If a file object was used instead of a filename, this
           parameter should always be used.
        :param options: Extra parameters to the image writer.
        :returns: None
        :exception KeyError: If the output format could not be determined
           from the file name.  Use the format option to solve this.
        :exception IOError: If the file could not be written.  The file
           may have been created, and may contain partial data.
        """

        if isPath(fp):
            filename = fp
        else:
            if hasattr(fp, "name") and isPath(fp.name):
                filename = fp.name
            else:
                filename = ""

        # may mutate self!
        self.load()

        self.encoderinfo = params
        self.encoderconfig = ()

        preinit()

        ext = os.path.splitext(filename)[1].lower()

        if not format:
            try:
                format = EXTENSION[ext]
            except KeyError:
                init()
                try:
                    format = EXTENSION[ext]
                except KeyError:
                    raise KeyError(ext) # unknown extension

        try:
            save_handler = SAVE[format.upper()]
        except KeyError:
            init()
            save_handler = SAVE[format.upper()] # unknown format

        if isPath(fp):
            fp = builtins.open(fp, "wb")
            close = 1
        else:
            close = 0

        try:
            save_handler(self, fp, filename)
        finally:
            # do what we can to clean up
            if close:
                fp.close()

    def seek(self, frame):
        """
        Seeks to the given frame in this sequence file. If you seek
        beyond the end of the sequence, the method raises an
        **EOFError** exception. When a sequence file is opened, the
        library automatically seeks to frame 0.

        Note that in the current version of the library, most sequence
        formats only allows you to seek to the next frame.

        See :func:`PIL.Image.Image.tell`.

        :param frame: Frame number, starting at 0.
        :exception EOFError: If the call attempts to seek beyond the end
            of the sequence.
        """

        # overridden by file handlers
        if frame != 0:
            raise EOFError

    def show(self, title=None, command=None):
        """
        Displays this image. This method is mainly intended for
        debugging purposes.

        On Unix platforms, this method saves the image to a temporary
        PPM file, and calls the **xv** utility.

        On Windows, it saves the image to a temporary BMP file, and uses
        the standard BMP display utility to show it (usually Paint).

        :param title: Optional title to use for the image window,
           where possible.
        :param command: command used to show the image
        """

        _show(self, title=title, command=command)

    def split(self):
        """
        Split this image into individual bands. This method returns a
        tuple of individual image bands from an image. For example,
        splitting an "RGB" image creates three new images each
        containing a copy of one of the original bands (red, green,
        blue).

        :returns: A tuple containing bands.
        """

        self.load()
        if self.im.bands == 1:
            ims = [self.copy()]
        else:
            ims = []
            for i in range(self.im.bands):
                ims.append(self._new(self.im.getband(i)))
        return tuple(ims)

    def tell(self):
        """
        Returns the current frame number. See :func:`PIL.Image.Image.seek`.

        :returns: Frame number, starting with 0.
        """
        return 0

    def thumbnail(self, size, resample=NEAREST):
        """
        Make this image into a thumbnail.  This method modifies the
        image to contain a thumbnail version of itself, no larger than
        the given size.  This method calculates an appropriate thumbnail
        size to preserve the aspect of the image, calls the
        :func:`PIL.Image.Image.draft` method to configure the file reader
        (where applicable), and finally resizes the image.

        Note that the bilinear and bicubic filters in the current
        version of PIL are not well-suited for thumbnail generation.
        You should use :attr:`PIL.Image.ANTIALIAS` unless speed is much more
        important than quality.

        Also note that this function modifies the Image object in place.
        If you need to use the full resolution image as well, apply this
        method to a :func:`PIL.Image.Image.copy` of the original image.

        :param size: Requested size.
        :param resample: Optional resampling filter.  This can be one
           of :attr:`PIL.Image.NEAREST`, :attr:`PIL.Image.BILINEAR`,
           :attr:`PIL.Image.BICUBIC`, or :attr:`PIL.Image.ANTIALIAS`
           (best quality).  If omitted, it defaults to
           :attr:`PIL.Image.NEAREST` (this will be changed to ANTIALIAS in a
           future version).
        :returns: None
        """

        # FIXME: the default resampling filter will be changed
        # to ANTIALIAS in future versions

        # preserve aspect ratio
        x, y = self.size
        if x > size[0]: y = int(max(y * size[0] / x, 1)); x = int(size[0])
        if y > size[1]: x = int(max(x * size[1] / y, 1)); y = int(size[1])
        size = x, y

        if size == self.size:
            return

        self.draft(None, size)

        self.load()

        try:
            im = self.resize(size, resample)
        except ValueError:
            if resample != ANTIALIAS:
                raise
            im = self.resize(size, NEAREST) # fallback

        self.im = im.im
        self.mode = im.mode
        self.size = size

        self.readonly = 0

    # FIXME: the different tranform methods need further explanation
    # instead of bloating the method docs, add a separate chapter.
    def transform(self, size, method, data=None, resample=NEAREST, fill=1):
        """
        Transforms this image.  This method creates a new image with the
        given size, and the same mode as the original, and copies data
        to the new image using the given transform.

        :param size: The output size.
        :param method: The transformation method.  This is one of
          :attr:`PIL.Image.EXTENT` (cut out a rectangular subregion),
          :attr:`PIL.Image.AFFINE` (affine transform),
          :attr:`PIL.Image.PERSPECTIVE` (perspective transform),
          :attr:`PIL.Image.QUAD` (map a quadrilateral to a rectangle), or
          :attr:`PIL.Image.MESH` (map a number of source quadrilaterals
          in one operation).
        :param data: Extra data to the transformation method.
        :param resample: Optional resampling filter.  It can be one of
           :attr:`PIL.Image.NEAREST` (use nearest neighbour),
           :attr:`PIL.Image.BILINEAR` (linear interpolation in a 2x2
           environment), or :attr:`PIL.Image.BICUBIC` (cubic spline
           interpolation in a 4x4 environment). If omitted, or if the image
           has mode "1" or "P", it is set to :attr:`PIL.Image.NEAREST`.
        :returns: An Image object.
        """

        if isinstance(method, ImageTransformHandler):
            return method.transform(size, self, resample=resample, fill=fill)
        if hasattr(method, "getdata"):
            # compatibility w. old-style transform objects
            method, data = method.getdata()
        if data is None:
            raise ValueError("missing method data")
        im = new(self.mode, size, None)
        if method == MESH:
            # list of quads
            for box, quad in data:
                im.__transformer(box, self, QUAD, quad, resample, fill)
        else:
            im.__transformer((0, 0)+size, self, method, data, resample, fill)

        return im

    def __transformer(self, box, image, method, data,
                      resample=NEAREST, fill=1):

        # FIXME: this should be turned into a lazy operation (?)

        w = box[2]-box[0]
        h = box[3]-box[1]

        if method == AFFINE:
            # change argument order to match implementation
            data = (data[2], data[0], data[1],
                    data[5], data[3], data[4])
        elif method == EXTENT:
            # convert extent to an affine transform
            x0, y0, x1, y1 = data
            xs = float(x1 - x0) / w
            ys = float(y1 - y0) / h
            method = AFFINE
            data = (x0 + xs/2, xs, 0, y0 + ys/2, 0, ys)
        elif method == PERSPECTIVE:
            # change argument order to match implementation
            data = (data[2], data[0], data[1],
                    data[5], data[3], data[4],
                    data[6], data[7])
        elif method == QUAD:
            # quadrilateral warp.  data specifies the four corners
            # given as NW, SW, SE, and NE.
            nw = data[0:2]; sw = data[2:4]; se = data[4:6]; ne = data[6:8]
            x0, y0 = nw; As = 1.0 / w; At = 1.0 / h
            data = (x0, (ne[0]-x0)*As, (sw[0]-x0)*At,
                    (se[0]-sw[0]-ne[0]+x0)*As*At,
                    y0, (ne[1]-y0)*As, (sw[1]-y0)*At,
                    (se[1]-sw[1]-ne[1]+y0)*As*At)
        else:
            raise ValueError("unknown transformation method")

        if resample not in (NEAREST, BILINEAR, BICUBIC):
            raise ValueError("unknown resampling filter")

        image.load()

        self.load()

        if image.mode in ("1", "P"):
            resample = NEAREST

        self.im.transform2(box, image.im, method, data, resample, fill)

    def transpose(self, method):
        """
        Transpose image (flip or rotate in 90 degree steps)

        :param method: One of :attr:`PIL.Image.FLIP_LEFT_RIGHT`,
          :attr:`PIL.Image.FLIP_TOP_BOTTOM`, :attr:`PIL.Image.ROTATE_90`,
          :attr:`PIL.Image.ROTATE_180`, or :attr:`PIL.Image.ROTATE_270`.
        :returns: Returns a flipped or rotated copy of this image.
        """

        self.load()
        im = self.im.transpose(method)
        return self._new(im)

# --------------------------------------------------------------------
# Lazy operations

class _ImageCrop(Image):

    def __init__(self, im, box):

        Image.__init__(self)

        x0, y0, x1, y1 = box
        if x1 < x0:
            x1 = x0
        if y1 < y0:
            y1 = y0

        self.mode = im.mode
        self.size = x1-x0, y1-y0

        self.__crop = x0, y0, x1, y1

        self.im = im.im

    def load(self):

        # lazy evaluation!
        if self.__crop:
            self.im = self.im.crop(self.__crop)
            self.__crop = None

        if self.im:
            return self.im.pixel_access(self.readonly)

        # FIXME: future versions should optimize crop/paste
        # sequences!

# --------------------------------------------------------------------
# Abstract handlers.

class ImagePointHandler:
    # used as a mixin by point transforms (for use with im.point)
    pass

class ImageTransformHandler:
    # used as a mixin by geometry transforms (for use with im.transform)
    pass

# --------------------------------------------------------------------
# Factories

#
# Debugging

def _wedge():
    "Create greyscale wedge (for debugging only)"

    return Image()._new(core.wedge("L"))


def new(mode, size, color=0):
    """
    Creates a new image with the given mode and size.

    :param mode: The mode to use for the new image.
    :param size: A 2-tuple, containing (width, height) in pixels.
    :param color: What colour to use for the image.  Default is black.
       If given, this should be a single integer or floating point value
       for single-band modes, and a tuple for multi-band modes (one value
       per band).  When creating RGB images, you can also use colour
       strings as supported by the ImageColor module.  If the colour is
       None, the image is not initialised.
    :returns: An Image object.
    """

    if color is None:
        # don't initialize
        return Image()._new(core.new(mode, size))

    if isStringType(color):
        # css3-style specifier

        from PIL import ImageColor
        color = ImageColor.getcolor(color, mode)

    return Image()._new(core.fill(mode, size, color))


def frombytes(mode, size, data, decoder_name="raw", *args):
    """
    Creates a copy of an image memory from pixel data in a buffer.

    In its simplest form, this function takes three arguments
    (mode, size, and unpacked pixel data).

    You can also use any pixel decoder supported by PIL.  For more
    information on available decoders, see the section
    **Writing Your Own File Decoder**.

    Note that this function decodes pixel data only, not entire images.
    If you have an entire image in a string, wrap it in a
    **BytesIO** object, and use :func:`PIL.Image.open` to load it.

    :param mode: The image mode.
    :param size: The image size.
    :param data: A byte buffer containing raw data for the given mode.
    :param decoder_name: What decoder to use.
    :param args: Additional parameters for the given decoder.
    :returns: An Image object.
    """

    # may pass tuple instead of argument list
    if len(args) == 1 and isinstance(args[0], tuple):
        args = args[0]

    if decoder_name == "raw" and args == ():
        args = mode

    im = new(mode, size)
    im.frombytes(data, decoder_name, args)
    return im

def fromstring(*args, **kw):
    " Deprecated alias to frombytes "
    warnings.warn(
        'fromstring() is deprecated. Please call frombytes() instead.',
        DeprecationWarning,
        stacklevel=2
    )
    return frombytes(*args, **kw)


def frombuffer(mode, size, data, decoder_name="raw", *args):
    """
    Creates an image memory referencing pixel data in a byte buffer.

    This function is similar to :func:`PIL.Image.frombytes`, but uses data in
    the byte buffer, where possible.  This means that changes to the
    original buffer object are reflected in this image).  Not all modes
    can share memory; supported modes include "L", "RGBX", "RGBA", and
    "CMYK".

    Note that this function decodes pixel data only, not entire images.
    If you have an entire image file in a string, wrap it in a
    **BytesIO** object, and use :func:`PIL.Image.open` to load it.

    In the current version, the default parameters used for the "raw" decoder
    differs from that used for :func:`PIL.Image.fromstring`.  This is a bug,
    and will probably be fixed in a future release.  The current release issues
    a warning if you do this; to disable the warning, you should provide the
    full set of parameters.  See below for details.

    :param mode: The image mode.
    :param size: The image size.
    :param data: A bytes or other buffer object containing raw
        data for the given mode.
    :param decoder_name: What decoder to use.
    :param args: Additional parameters for the given decoder.  For the
        default encoder ("raw"), it's recommended that you provide the
        full set of parameters::

            frombuffer(mode, size, data, "raw", mode, 0, 1)

    :returns: An Image object.

    .. versionadded:: 1.1.4
    """
    "Load image from bytes or buffer"

    # may pass tuple instead of argument list
    if len(args) == 1 and isinstance(args[0], tuple):
        args = args[0]

    if decoder_name == "raw":
        if args == ():
            if warnings:
                warnings.warn(
                    "the frombuffer defaults may change in a future release; "
                    "for portability, change the call to read:\n"
                    "  frombuffer(mode, size, data, 'raw', mode, 0, 1)",
                    RuntimeWarning, stacklevel=2
                )
            args = mode, 0, -1 # may change to (mode, 0, 1) post-1.1.6
        if args[0] in _MAPMODES:
            im = new(mode, (1,1))
            im = im._new(
                core.map_buffer(data, size, decoder_name, None, 0, args)
                )
            im.readonly = 1
            return im

    return frombytes(mode, size, data, decoder_name, args)


def fromarray(obj, mode=None):
    """
    Creates an image memory from an object exporting the array interface
    (using the buffer protocol).

    If obj is not contiguous, then the tobytes method is called
    and :func:`PIL.Image.frombuffer` is used.

    :param obj: Object with array interface
    :param mode: Mode to use (will be determined from type if None)
    :returns: An image memory.

    .. versionadded:: 1.1.6
    """
    arr = obj.__array_interface__
    shape = arr['shape']
    ndim = len(shape)
    try:
        strides = arr['strides']
    except KeyError:
        strides = None
    if mode is None:
        try:
            typekey = (1, 1) + shape[2:], arr['typestr']
            mode, rawmode = _fromarray_typemap[typekey]
        except KeyError:
            # print typekey
            raise TypeError("Cannot handle this data type")
    else:
        rawmode = mode
    if mode in ["1", "L", "I", "P", "F"]:
        ndmax = 2
    elif mode == "RGB":
        ndmax = 3
    else:
        ndmax = 4
    if ndim > ndmax:
        raise ValueError("Too many dimensions.")

    size = shape[1], shape[0]
    if strides is not None:
        if hasattr(obj, 'tobytes'):
            obj = obj.tobytes()
        else:
            obj = obj.tostring()

    return frombuffer(mode, size, obj, "raw", rawmode, 0, 1)

_fromarray_typemap = {
    # (shape, typestr) => mode, rawmode
    # first two members of shape are set to one
    # ((1, 1), "|b1"): ("1", "1"), # broken
    ((1, 1), "|u1"): ("L", "L"),
    ((1, 1), "|i1"): ("I", "I;8"),
    ((1, 1), "<i2"): ("I", "I;16"),
    ((1, 1), ">i2"): ("I", "I;16B"),
    ((1, 1), "<i4"): ("I", "I;32"),
    ((1, 1), ">i4"): ("I", "I;32B"),
    ((1, 1), "<f4"): ("F", "F;32F"),
    ((1, 1), ">f4"): ("F", "F;32BF"),
    ((1, 1), "<f8"): ("F", "F;64F"),
    ((1, 1), ">f8"): ("F", "F;64BF"),
    ((1, 1, 3), "|u1"): ("RGB", "RGB"),
    ((1, 1, 4), "|u1"): ("RGBA", "RGBA"),
    }

# shortcuts
_fromarray_typemap[((1, 1), _ENDIAN + "i4")] = ("I", "I")
_fromarray_typemap[((1, 1), _ENDIAN + "f4")] = ("F", "F")


def open(fp, mode="r"):
    """
    Opens and identifies the given image file.

    This is a lazy operation; this function identifies the file, but the
    actual image data is not read from the file until you try to process
    the data (or call the :func:`PIL.Image.Image.load` method).
    See :func:`PIL.Image.new`

    :param file: A filename (string) or a file object.  The file object
       must implement **read**, **seek**, and **tell** methods,
       and be opened in binary mode.
    :param mode: The mode.  If given, this argument must be "r".
    :returns: An Image object.
    :exception IOError: If the file cannot be found, or the image cannot be
       opened and identified.
    """

    if mode != "r":
        raise ValueError("bad mode")

    if isPath(fp):
        filename = fp
        fp = builtins.open(fp, "rb")
    else:
        filename = ""

    prefix = fp.read(16)

    preinit()

    for i in ID:
        try:
            factory, accept = OPEN[i]
            if not accept or accept(prefix):
                fp.seek(0)
                return factory(fp, filename)
        except (SyntaxError, IndexError, TypeError):
            #import traceback
            #traceback.print_exc()
            pass

    if init():

        for i in ID:
            try:
                factory, accept = OPEN[i]
                if not accept or accept(prefix):
                    fp.seek(0)
                    return factory(fp, filename)
            except (SyntaxError, IndexError, TypeError):
                #import traceback
                #traceback.print_exc()
                pass

    raise IOError("cannot identify image file")

#
# Image processing.

def alpha_composite(im1, im2):
    """
    Alpha composite im2 over im1.

    :param im1: The first image.
    :param im2: The second image.  Must have the same mode and size as
       the first image.
    :returns: An Image object.
    """

    im1.load()
    im2.load()
    return im1._new(core.alpha_composite(im1.im, im2.im))


def blend(im1, im2, alpha):
    """
    Creates a new image by interpolating between two input images, using
    a constant alpha.::

        out = image1 * (1.0 - alpha) + image2 * alpha

    :param im1: The first image.
    :param im2: The second image.  Must have the same mode and size as
       the first image.
    :param alpha: The interpolation alpha factor.  If alpha is 0.0, a
       copy of the first image is returned. If alpha is 1.0, a copy of
       the second image is returned. There are no restrictions on the
       alpha value. If necessary, the result is clipped to fit into
       the allowed output range.
    :returns: An Image object.
    """

    im1.load()
    im2.load()
    return im1._new(core.blend(im1.im, im2.im, alpha))


def composite(image1, image2, mask):
    """
    Create composite image by blending images using a transparency mask.

    :param image1: The first image.
    :param image2: The second image.  Must have the same mode and
       size as the first image.
    :param mask: A mask image.  This image can can have mode
       "1", "L", or "RGBA", and must have the same size as the
       other two images.
    """

    image = image2.copy()
    image.paste(image1, None, mask)
    return image


def eval(image, *args):
    """
    Applies the function (which should take one argument) to each pixel
    in the given image. If the image has more than one band, the same
    function is applied to each band. Note that the function is
    evaluated once for each possible pixel value, so you cannot use
    random components or other generators.

    :param image: The input image.
    :param function: A function object, taking one integer argument.
    :returns: An Image object.
    """

    return image.point(args[0])


def merge(mode, bands):
    """
    Merge a set of single band images into a new multiband image.

    :param mode: The mode to use for the output image.
    :param bands: A sequence containing one single-band image for
        each band in the output image.  All bands must have the
        same size.
    :returns: An Image object.
    """

    if getmodebands(mode) != len(bands) or "*" in mode:
        raise ValueError("wrong number of bands")
    for im in bands[1:]:
        if im.mode != getmodetype(mode):
            raise ValueError("mode mismatch")
        if im.size != bands[0].size:
            raise ValueError("size mismatch")
    im = core.new(mode, bands[0].size)
    for i in range(getmodebands(mode)):
        bands[i].load()
        im.putband(bands[i].im, i)
    return bands[0]._new(im)

# --------------------------------------------------------------------
# Plugin registry

def register_open(id, factory, accept=None):
    """
    Register an image file plugin.  This function should not be used
    in application code.

    :param id: An image format identifier.
    :param factory: An image file factory method.
    :param accept: An optional function that can be used to quickly
       reject images having another format.
    """
    id = id.upper()
    ID.append(id)
    OPEN[id] = factory, accept


def register_mime(id, mimetype):
    """
    Registers an image MIME type.  This function should not be used
    in application code.

    :param id: An image format identifier.
    :param mimetype: The image MIME type for this format.
    """
    MIME[id.upper()] = mimetype


def register_save(id, driver):
    """
    Registers an image save function.  This function should not be
    used in application code.

    :param id: An image format identifier.
    :param driver: A function to save images in this format.
    """
    SAVE[id.upper()] = driver


def register_extension(id, extension):
    """
    Registers an image extension.  This function should not be
    used in application code.

    :param id: An image format identifier.
    :param extension: An extension used for this format.
    """
    EXTENSION[extension.lower()] = id.upper()


# --------------------------------------------------------------------
# Simple display support.  User code may override this.

def _show(image, **options):
    # override me, as necessary
    _showxv(image, **options)

def _showxv(image, title=None, **options):
    from PIL import ImageShow
    ImageShow.show(image, title, **options)