# -*- coding: utf-8 -*-
# imageio is distributed under the terms of the (new) BSD License.

"""Read/Write images using pillow/PIL (legacy).

Backend Library: `Pillow <https://pillow.readthedocs.io/en/stable/>`_

Pillow is a friendly fork of PIL (Python Image Library) and supports
reading and writing of common formats (jpg, png, gif, tiff, ...). While
these docs provide an overview of some of its features, pillow is
constantly improving. Hence, the complete list of features can be found
in pillows official docs (see the Backend Library link).

Parameters for Reading
----------------------
pilmode : str
    (Available for all formats except GIF-PIL)
    From the Pillow documentation:

    * 'L' (8-bit pixels, grayscale)
    * 'P' (8-bit pixels, mapped to any other mode using a color palette)
    * 'RGB' (3x8-bit pixels, true color)
    * 'RGBA' (4x8-bit pixels, true color with transparency mask)
    * 'CMYK' (4x8-bit pixels, color separation)
    * 'YCbCr' (3x8-bit pixels, color video format)
    * 'I' (32-bit signed integer pixels)
    * 'F' (32-bit floating point pixels)

    PIL also provides limited support for a few special modes, including
    'LA' ('L' with alpha), 'RGBX' (true color with padding) and 'RGBa'
    (true color with premultiplied alpha).

    When translating a color image to grayscale (mode 'L', 'I' or 'F'),
    the library uses the ITU-R 601-2 luma transform::

        L = R * 299/1000 + G * 587/1000 + B * 114/1000
as_gray : bool
    (Available for all formats except GIF-PIL)
    If True, the image is converted using mode 'F'. When `mode` is
    not None and `as_gray` is True, the image is first converted
    according to `mode`, and the result is then "flattened" using
    mode 'F'.
ignoregamma : bool
    (Only available in PNG-PIL)
    Avoid gamma correction. Default True.
exifrotate : bool
    (Only available in JPEG-PIL)
    Automatically rotate the image according to exif flag. Default True.


Parameters for saving
---------------------
optimize : bool
    (Only available in PNG-PIL)
    If present and true, instructs the PNG writer to make the output file
    as small as possible. This includes extra processing in order to find
    optimal encoder settings.
transparency:
    (Only available in PNG-PIL)
    This option controls what color image to mark as transparent.
dpi: tuple of two scalars
    (Only available in PNG-PIL)
    The desired dpi in each direction.
pnginfo: PIL.PngImagePlugin.PngInfo
    (Only available in PNG-PIL)
    Object containing text tags.
compress_level: int
    (Only available in PNG-PIL)
    ZLIB compression level, a number between 0 and 9: 1 gives best speed,
    9 gives best compression, 0 gives no compression at all. Default is 9.
    When ``optimize`` option is True ``compress_level`` has no effect
    (it is set to 9 regardless of a value passed).
compression: int
    (Only available in PNG-PIL)
    Compatibility with the freeimage PNG format. If given, it overrides
    compress_level.
icc_profile:
    (Only available in PNG-PIL)
    The ICC Profile to include in the saved file.
bits (experimental): int
    (Only available in PNG-PIL)
    This option controls how many bits to store. If omitted,
    the PNG writer uses 8 bits (256 colors).
quantize:
    (Only available in PNG-PIL)
    Compatibility with the freeimage PNG format. If given, it overrides
    bits. In this case, given as a number between 1-256.
dictionary (experimental): dict
    (Only available in PNG-PIL)
    Set the ZLIB encoder dictionary.
prefer_uint8: bool
    (Only available in PNG-PIL)
    Let the PNG writer truncate uint16 image arrays to uint8 if their values fall
    within the range [0, 255]. Defaults to true for legacy compatibility, however
    it is recommended to set this to false to avoid unexpected behavior when
    saving e.g. weakly saturated images.

quality : scalar
    (Only available in JPEG-PIL)
    The compression factor of the saved image (1..100), higher
    numbers result in higher quality but larger file size. Default 75.
progressive : bool
    (Only available in JPEG-PIL)
    Save as a progressive JPEG file (e.g. for images on the web).
    Default False.
optimize : bool
    (Only available in JPEG-PIL)
    On saving, compute optimal Huffman coding tables (can reduce a few
    percent of file size). Default False.
dpi : tuple of int
    (Only available in JPEG-PIL)
    The pixel density, ``(x,y)``.
icc_profile : object
    (Only available in JPEG-PIL)
    If present and true, the image is stored with the provided ICC profile.
    If this parameter is not provided, the image will be saved with no
    profile attached.
exif : dict
    (Only available in JPEG-PIL)
    If present, the image will be stored with the provided raw EXIF data.
subsampling : str
    (Only available in JPEG-PIL)
    Sets the subsampling for the encoder. See Pillow docs for details.
qtables : object
    (Only available in JPEG-PIL)
    Set the qtables for the encoder. See Pillow docs for details.
quality_mode : str
    (Only available in JPEG2000-PIL)
    Either `"rates"` or `"dB"` depending on the units you want to use to
    specify image quality.
quality : float
    (Only available in JPEG2000-PIL)
    Approximate size reduction (if quality mode is `rates`) or a signal to noise ratio
    in decibels (if quality mode is `dB`).
loop : int
    (Only available in GIF-PIL)
    The number of iterations. Default 0 (meaning loop indefinitely).
duration : {float, list}
    (Only available in GIF-PIL)
    The duration (in milliseconds) of each frame. Either specify one value
    that is used for all frames, or one value for each frame.
fps : float
    (Only available in GIF-PIL)
    The number of frames per second. If duration is not given, the
    duration for each frame is set to 1/fps. Default 10.
palettesize : int
    (Only available in GIF-PIL)
    The number of colors to quantize the image to. Is rounded to
    the nearest power of two. Default 256.
subrectangles : bool
    (Only available in GIF-PIL)
    If True, will try and optimize the GIF by storing only the
    rectangular parts of each frame that change with respect to the
    previous. Default False.

Notes
-----
To enable JPEG 2000 support, you need to build and install the OpenJPEG library,
version 2.0.0 or higher, before building the Python Imaging Library. Windows
users can install the OpenJPEG binaries available on the OpenJPEG website, but
must add them to their PATH in order to use PIL (if you fail to do this, you
will get errors about not being able to load the ``_imaging`` DLL).

GIF images read with this plugin are always RGBA. The alpha channel is ignored
when saving RGB images.
"""

import logging
import threading

import numpy as np

from ..core import Format, image_as_uint
from ..core.request import URI_FILE, URI_BYTES

logger = logging.getLogger(__name__)


# todo: Pillow ImageGrab module supports grabbing the screen on Win and OSX.


GENERIC_DOCS = """
    Parameters for reading
    ----------------------

    pilmode : str
        From the Pillow documentation:

        * 'L' (8-bit pixels, grayscale)
        * 'P' (8-bit pixels, mapped to any other mode using a color palette)
        * 'RGB' (3x8-bit pixels, true color)
        * 'RGBA' (4x8-bit pixels, true color with transparency mask)
        * 'CMYK' (4x8-bit pixels, color separation)
        * 'YCbCr' (3x8-bit pixels, color video format)
        * 'I' (32-bit signed integer pixels)
        * 'F' (32-bit floating point pixels)

        PIL also provides limited support for a few special modes, including
        'LA' ('L' with alpha), 'RGBX' (true color with padding) and 'RGBa'
        (true color with premultiplied alpha).

        When translating a color image to grayscale (mode 'L', 'I' or 'F'),
        the library uses the ITU-R 601-2 luma transform::

            L = R * 299/1000 + G * 587/1000 + B * 114/1000
    as_gray : bool
        If True, the image is converted using mode 'F'. When `mode` is
        not None and `as_gray` is True, the image is first converted
        according to `mode`, and the result is then "flattened" using
        mode 'F'.
"""


class PillowFormat(Format):
    """
    Base format class for Pillow formats.
    """

    _pillow_imported = False
    _Image = None
    _modes = "i"
    _description = ""

    def __init__(self, *args, plugin_id: str = None, **kwargs):
        super(PillowFormat, self).__init__(*args, **kwargs)
        # Used to synchronize _init_pillow(), see #244
        self._lock = threading.RLock()

        self._plugin_id = plugin_id

    @property
    def plugin_id(self):
        """The PIL plugin id."""
        return self._plugin_id  # Set when format is created

    def _init_pillow(self):
        with self._lock:
            if not self._pillow_imported:
                self._pillow_imported = True  # more like tried to import
                import PIL

                if not hasattr(PIL, "__version__"):  # pragma: no cover
                    raise ImportError(
                        "Imageio Pillow plugin requires " "Pillow, not PIL!"
                    )
                from PIL import Image

                self._Image = Image
            elif self._Image is None:  # pragma: no cover
                raise RuntimeError("Imageio Pillow plugin requires " "Pillow lib.")
            Image = self._Image

        if self.plugin_id in ("PNG", "JPEG", "BMP", "GIF", "PPM"):
            Image.preinit()
        else:
            Image.init()
        return Image

    def _can_read(self, request):
        Image = self._init_pillow()
        if self.plugin_id in Image.OPEN:
            factory, accept = Image.OPEN[self.plugin_id]
            if accept:
                if request.firstbytes and accept(request.firstbytes):
                    return True

    def _can_write(self, request):
        Image = self._init_pillow()
        if request.extension in self.extensions or request._uri_type in [
            URI_FILE,
            URI_BYTES,
        ]:
            if self.plugin_id in Image.SAVE:
                return True

    class Reader(Format.Reader):
        def _open(self, pilmode=None, as_gray=False):
            Image = self.format._init_pillow()
            try:
                factory, accept = Image.OPEN[self.format.plugin_id]
            except KeyError:
                raise RuntimeError("Format %s cannot read images." % self.format.name)
            self._fp = self._get_file()
            self._im = factory(self._fp, "")
            if hasattr(Image, "_decompression_bomb_check"):
                Image._decompression_bomb_check(self._im.size)
            # Save the raw mode used by the palette for a BMP because it may not be the number of channels
            # When the data is read, imageio hands the palette to PIL to handle and clears the rawmode argument
            # However, there is a bug in PIL with handling animated GIFs with a different color palette on each frame.
            # This issue is resolved by using the raw palette data but the rawmode information is now lost. So we
            # store the raw mode for later use
            if self._im.palette and self._im.palette.dirty:
                self._im.palette.rawmode_saved = self._im.palette.rawmode
            pil_try_read(self._im)
            # Store args
            self._kwargs = dict(
                as_gray=as_gray, is_gray=_palette_is_grayscale(self._im)
            )
            # setting mode=None is not the same as just not providing it
            if pilmode is not None:
                self._kwargs["mode"] = pilmode
            # Set length
            self._length = 1
            if hasattr(self._im, "n_frames"):
                self._length = self._im.n_frames

        def _get_file(self):
            self._we_own_fp = False
            return self.request.get_file()

        def _close(self):
            save_pillow_close(self._im)
            if self._we_own_fp:
                self._fp.close()
            # else: request object handles closing the _fp

        def _get_length(self):
            return self._length

        def _seek(self, index):
            try:
                self._im.seek(index)
            except EOFError:
                raise IndexError("Could not seek to index %i" % index)

        def _get_data(self, index):
            if index >= self._length:
                raise IndexError("Image index %i > %i" % (index, self._length))
            i = self._im.tell()
            if i > index:
                self._seek(index)  # just try
            else:
                while i < index:  # some formats need to be read in sequence
                    i += 1
                    self._seek(i)
            if self._im.palette and self._im.palette.dirty:
                self._im.palette.rawmode_saved = self._im.palette.rawmode
            self._im.getdata()[0]
            im = pil_get_frame(self._im, **self._kwargs)
            return im, self._im.info

        def _get_meta_data(self, index):
            if not (index is None or index == 0):
                raise IndexError()
            return self._im.info

    class Writer(Format.Writer):
        def _open(self):
            Image = self.format._init_pillow()
            try:
                self._save_func = Image.SAVE[self.format.plugin_id]
            except KeyError:
                raise RuntimeError("Format %s cannot write images." % self.format.name)
            self._fp = self.request.get_file()
            self._meta = {}
            self._written = False

        def _close(self):
            pass  # request object handled closing _fp

        def _append_data(self, im, meta):
            if self._written:
                raise RuntimeError(
                    "Format %s only supports single images." % self.format.name
                )
            # Pop unit dimension for grayscale images
            if im.ndim == 3 and im.shape[-1] == 1:
                im = im[:, :, 0]
            self._written = True
            self._meta.update(meta)
            img = ndarray_to_pil(
                im, self.format.plugin_id, self._meta.pop("prefer_uint8", True)
            )
            if "bits" in self._meta:
                img = img.quantize()  # Make it a P image, so bits arg is used
            img.save(self._fp, format=self.format.plugin_id, **self._meta)
            save_pillow_close(img)

        def set_meta_data(self, meta):
            self._meta.update(meta)


class PNGFormat(PillowFormat):
    """See :mod:`imageio.plugins.pillow_legacy`"""

    class Reader(PillowFormat.Reader):
        def _open(self, pilmode=None, as_gray=False, ignoregamma=True):
            return PillowFormat.Reader._open(self, pilmode=pilmode, as_gray=as_gray)

        def _get_data(self, index):
            im, info = PillowFormat.Reader._get_data(self, index)
            if not self.request.kwargs.get("ignoregamma", True):
                # The gamma value in the file represents the gamma factor for the
                # hardware on the system where the file was created, and is meant
                # to be able to match the colors with the system on which the
                # image is shown. See also issue #366
                try:
                    gamma = float(info["gamma"])
                except (KeyError, ValueError):
                    pass
                else:
                    scale = float(65536 if im.dtype == np.uint16 else 255)
                    gain = 1.0
                    im[:] = ((im / scale) ** gamma) * scale * gain + 0.4999
            return im, info

    # --

    class Writer(PillowFormat.Writer):
        def _open(self, compression=None, quantize=None, interlaced=False, **kwargs):
            # Better default for compression
            kwargs["compress_level"] = kwargs.get("compress_level", 9)

            if compression is not None:
                if compression < 0 or compression > 9:
                    raise ValueError("Invalid PNG compression level: %r" % compression)
                kwargs["compress_level"] = compression
            if quantize is not None:
                for bits in range(1, 9):
                    if 2**bits == quantize:
                        break
                else:
                    raise ValueError(
                        "PNG quantize must be power of two, " "not %r" % quantize
                    )
                kwargs["bits"] = bits
            if interlaced:
                logger.warning("PIL PNG writer cannot produce interlaced images.")

            ok_keys = (
                "optimize",
                "transparency",
                "dpi",
                "pnginfo",
                "bits",
                "compress_level",
                "icc_profile",
                "dictionary",
                "prefer_uint8",
            )
            for key in kwargs:
                if key not in ok_keys:
                    raise TypeError("Invalid arg for PNG writer: %r" % key)

            PillowFormat.Writer._open(self)
            self._meta.update(kwargs)

        def _append_data(self, im, meta):
            if str(im.dtype) == "uint16" and (im.ndim == 2 or im.shape[-1] == 1):
                im = image_as_uint(im, bitdepth=16)
            else:
                im = image_as_uint(im, bitdepth=8)
            PillowFormat.Writer._append_data(self, im, meta)


class JPEGFormat(PillowFormat):
    """See :mod:`imageio.plugins.pillow_legacy`"""

    class Reader(PillowFormat.Reader):
        def _open(self, pilmode=None, as_gray=False, exifrotate=True):
            return PillowFormat.Reader._open(self, pilmode=pilmode, as_gray=as_gray)

        def _get_file(self):
            # Pillow uses seek for JPG, so we cannot directly stream from web
            if self.request.filename.startswith(
                ("http://", "https://")
            ) or ".zip/" in self.request.filename.replace("\\", "/"):
                self._we_own_fp = True
                return open(self.request.get_local_filename(), "rb")
            else:
                self._we_own_fp = False
                return self.request.get_file()

        def _get_data(self, index):
            im, info = PillowFormat.Reader._get_data(self, index)

            # Handle exif
            if "exif" in info:
                from PIL.ExifTags import TAGS

                info["EXIF_MAIN"] = {}
                for tag, value in self._im._getexif().items():
                    decoded = TAGS.get(tag, tag)
                    info["EXIF_MAIN"][decoded] = value

            im = self._rotate(im, info)
            return im, info

        def _rotate(self, im, meta):
            """Use Orientation information from EXIF meta data to
            orient the image correctly. Similar code as in FreeImage plugin.
            """
            if self.request.kwargs.get("exifrotate", True):
                try:
                    ori = meta["EXIF_MAIN"]["Orientation"]
                except KeyError:  # pragma: no cover
                    pass  # Orientation not available
                else:  # pragma: no cover - we cannot touch all cases
                    # www.impulseadventure.com/photo/exif-orientation.html
                    if ori in [1, 2]:
                        pass
                    if ori in [3, 4]:
                        im = np.rot90(im, 2)
                    if ori in [5, 6]:
                        im = np.rot90(im, 3)
                    if ori in [7, 8]:
                        im = np.rot90(im)
                    if ori in [2, 4, 5, 7]:  # Flipped cases (rare)
                        im = np.fliplr(im)
            return im

    # --

    class Writer(PillowFormat.Writer):
        def _open(self, quality=75, progressive=False, optimize=False, **kwargs):
            # The JPEG quality can be between 0 (worst) and 100 (best)
            quality = int(quality)
            if quality < 0 or quality > 100:
                raise ValueError("JPEG quality should be between 0 and 100.")

            kwargs["quality"] = quality
            kwargs["progressive"] = bool(progressive)
            kwargs["optimize"] = bool(progressive)

            PillowFormat.Writer._open(self)
            self._meta.update(kwargs)

        def _append_data(self, im, meta):
            if im.ndim == 3 and im.shape[-1] == 4:
                raise IOError("JPEG does not support alpha channel.")
            im = image_as_uint(im, bitdepth=8)
            PillowFormat.Writer._append_data(self, im, meta)
            return


class JPEG2000Format(PillowFormat):
    """See :mod:`imageio.plugins.pillow_legacy`"""

    class Reader(PillowFormat.Reader):
        def _open(self, pilmode=None, as_gray=False):
            return PillowFormat.Reader._open(self, pilmode=pilmode, as_gray=as_gray)

        def _get_file(self):
            # Pillow uses seek for JPG, so we cannot directly stream from web
            if self.request.filename.startswith(
                ("http://", "https://")
            ) or ".zip/" in self.request.filename.replace("\\", "/"):
                self._we_own_fp = True
                return open(self.request.get_local_filename(), "rb")
            else:
                self._we_own_fp = False
                return self.request.get_file()

        def _get_data(self, index):
            im, info = PillowFormat.Reader._get_data(self, index)

            # Handle exif
            if "exif" in info:
                from PIL.ExifTags import TAGS

                info["EXIF_MAIN"] = {}
                for tag, value in self._im._getexif().items():
                    decoded = TAGS.get(tag, tag)
                    info["EXIF_MAIN"][decoded] = value

            im = self._rotate(im, info)
            return im, info

        def _rotate(self, im, meta):
            """Use Orientation information from EXIF meta data to
            orient the image correctly. Similar code as in FreeImage plugin.
            """
            if self.request.kwargs.get("exifrotate", True):
                try:
                    ori = meta["EXIF_MAIN"]["Orientation"]
                except KeyError:  # pragma: no cover
                    pass  # Orientation not available
                else:  # pragma: no cover - we cannot touch all cases
                    # www.impulseadventure.com/photo/exif-orientation.html
                    if ori in [1, 2]:
                        pass
                    if ori in [3, 4]:
                        im = np.rot90(im, 2)
                    if ori in [5, 6]:
                        im = np.rot90(im, 3)
                    if ori in [7, 8]:
                        im = np.rot90(im)
                    if ori in [2, 4, 5, 7]:  # Flipped cases (rare)
                        im = np.fliplr(im)
            return im

    # --

    class Writer(PillowFormat.Writer):
        def _open(self, quality_mode="rates", quality=5, **kwargs):
            # Check quality - in Pillow it should be no higher than 95
            if quality_mode not in {"rates", "dB"}:
                raise ValueError("Quality mode should be either 'rates' or 'dB'")

            quality = float(quality)

            if quality_mode == "rates" and (quality < 1 or quality > 1000):
                raise ValueError(
                    "The quality value {} seems to be an invalid rate!".format(quality)
                )
            elif quality_mode == "dB" and (quality < 15 or quality > 100):
                raise ValueError(
                    "The quality value {} seems to be an invalid PSNR!".format(quality)
                )

            kwargs["quality_mode"] = quality_mode
            kwargs["quality_layers"] = [quality]

            PillowFormat.Writer._open(self)
            self._meta.update(kwargs)

        def _append_data(self, im, meta):
            if im.ndim == 3 and im.shape[-1] == 4:
                raise IOError(
                    "The current implementation of JPEG 2000 does not support alpha channel."
                )
            im = image_as_uint(im, bitdepth=8)
            PillowFormat.Writer._append_data(self, im, meta)
            return


def save_pillow_close(im):
    # see issue #216 and #300
    if hasattr(im, "close"):
        if hasattr(getattr(im, "fp", None), "close"):
            im.close()


# Func from skimage

# This cells contains code from scikit-image, in particular from
# http://github.com/scikit-image/scikit-image/blob/master/
# skimage/io/_plugins/pil_plugin.py
# The scikit-image license applies.


def pil_try_read(im):
    try:
        # this will raise an IOError if the file is not readable
        im.getdata()[0]
    except IOError as e:
        site = "http://pillow.readthedocs.io/en/latest/installation.html"
        site += "#external-libraries"
        pillow_error_message = str(e)
        error_message = (
            'Could not load "%s" \n'
            'Reason: "%s"\n'
            "Please see documentation at: %s"
            % (im.filename, pillow_error_message, site)
        )
        raise ValueError(error_message)


def _palette_is_grayscale(pil_image):
    if pil_image.mode != "P":
        return False
    elif pil_image.info.get("transparency", None):  # see issue #475
        return False
    # get palette as an array with R, G, B columns
    # Note: starting in pillow 9.1 palettes may have less than 256 entries
    palette = np.asarray(pil_image.getpalette()).reshape((-1, 3))
    # Not all palette colors are used; unused colors have junk values.
    start, stop = pil_image.getextrema()
    valid_palette = palette[start : stop + 1]
    # Image is grayscale if channel differences (R - G and G - B)
    # are all zero.
    return np.allclose(np.diff(valid_palette), 0)


def pil_get_frame(im, is_gray=None, as_gray=None, mode=None, dtype=None):
    """
    is_gray: Whether the image *is* gray (by inspecting its palette).
    as_gray: Whether the resulting image must be converted to gaey.
    mode: The mode to convert to.
    """

    if is_gray is None:
        is_gray = _palette_is_grayscale(im)

    frame = im

    # Convert ...
    if mode is not None:
        # Mode is explicitly given ...
        if mode != im.mode:
            frame = im.convert(mode)
    elif as_gray:
        pass  # don't do any auto-conversions (but do the explicit one above)
    elif im.mode == "P" and is_gray:
        # Paletted images that are already gray by their palette
        # are converted so that the resulting numpy array is 2D.
        frame = im.convert("L")
    elif im.mode == "P":
        # Paletted images are converted to RGB/RGBA. We jump some loops to make
        # this work well.
        if im.info.get("transparency", None) is not None:
            # Let Pillow apply the transparency, see issue #210 and #246
            frame = im.convert("RGBA")
        elif im.palette.mode in ("RGB", "RGBA"):
            # We can do this ourselves. Pillow seems to sometimes screw
            # this up if a  multi-gif has a palette for each frame ...
            # Create palette array
            p = np.frombuffer(im.palette.getdata()[1], np.uint8)
            # Restore the raw mode that was saved to be used to parse the palette
            if hasattr(im.palette, "rawmode_saved"):
                im.palette.rawmode = im.palette.rawmode_saved
            mode = im.palette.rawmode if im.palette.rawmode else im.palette.mode
            nchannels = len(mode)
            # Shape it.
            p.shape = -1, nchannels
            if p.shape[1] == 3 or (p.shape[1] == 4 and mode[-1] == "X"):
                p = np.column_stack((p[:, :3], 255 * np.ones(p.shape[0], p.dtype)))
            # Swap the axes if the mode is in BGR and not RGB
            if mode.startswith("BGR"):
                p = p[:, [2, 1, 0]] if p.shape[1] == 3 else p[:, [2, 1, 0, 3]]
            # Apply palette
            frame_paletted = np.array(im, np.uint8)
            try:
                frame = p[frame_paletted]
            except Exception:
                # Ok, let PIL do it. The introduction of the branch that
                # tests `im.info['transparency']` should make this happen
                # much less often, but let's keep it, to be safe.
                frame = im.convert("RGBA")
        else:
            # Let Pillow do it. Unlinke skimage, we always convert
            # to RGBA; palettes can be RGBA.
            if True:  # im.format == 'PNG' and 'transparency' in im.info:
                frame = im.convert("RGBA")
            else:
                frame = im.convert("RGB")
    elif "A" in im.mode:
        frame = im.convert("RGBA")
    elif im.mode == "CMYK":
        frame = im.convert("RGB")
    elif im.format == "GIF" and im.mode == "RGB":
        # pillow9 returns RGBA images for subsequent frames so that it can deal
        # with multi-frame GIF that use frame-level palettes and don't dispose
        # all areas.

        # For backwards compatibility, we promote everything to RGBA.
        frame = im.convert("RGBA")

    # Apply a post-convert if necessary
    if as_gray:
        frame = frame.convert("F")  # Scipy compat
    elif not isinstance(frame, np.ndarray) and frame.mode == "1":
        # Workaround for crash in PIL. When im is 1-bit, the call array(im)
        # can cause a segfault, or generate garbage. See
        # https://github.com/scipy/scipy/issues/2138 and
        # https://github.com/python-pillow/Pillow/issues/350.
        #
        # This converts im from a 1-bit image to an 8-bit image.
        frame = frame.convert("L")

    # Convert to numpy array
    if im.mode.startswith("I;16"):
        # e.g. in16 PNG's
        shape = im.size
        dtype = ">u2" if im.mode.endswith("B") else "<u2"
        if "S" in im.mode:
            dtype = dtype.replace("u", "i")
        frame = np.frombuffer(frame.tobytes(), dtype).copy()
        frame.shape = shape[::-1]
    else:
        # Use uint16 for PNG's in mode I
        if im.format == "PNG" and im.mode == "I" and dtype is None:
            dtype = "uint16"
        frame = np.array(frame, dtype=dtype)

    return frame


def ndarray_to_pil(arr, format_str=None, prefer_uint8=True):
    from PIL import Image

    if arr.ndim == 3:
        arr = image_as_uint(arr, bitdepth=8)
        mode = {3: "RGB", 4: "RGBA"}[arr.shape[2]]

    elif format_str in ["png", "PNG"]:
        mode = "I;16"
        mode_base = "I"

        if arr.dtype.kind == "f":
            arr = image_as_uint(arr)

        elif prefer_uint8 and arr.max() < 256 and arr.min() >= 0:
            arr = arr.astype(np.uint8)
            mode = mode_base = "L"

        else:
            arr = image_as_uint(arr, bitdepth=16)

    else:
        arr = image_as_uint(arr, bitdepth=8)
        mode = "L"
        mode_base = "L"

    if mode == "I;16" and int(getattr(Image, "__version__", "0").split(".")[0]) < 6:
        # Pillow < v6.0.0 has limited support for the "I;16" mode,
        # requiring us to fall back to this expensive workaround.
        # tobytes actually creates a copy of the image, which is costly.
        array_buffer = arr.tobytes()
        if arr.ndim == 2:
            im = Image.new(mode_base, arr.T.shape)
            im.frombytes(array_buffer, "raw", mode)
        else:
            image_shape = (arr.shape[1], arr.shape[0])
            im = Image.frombytes(mode, image_shape, array_buffer)
        return im
    else:
        return Image.fromarray(arr, mode)


# imported for backwards compatibility
from .pillowmulti import GIFFormat, TIFFFormat  # noqa: E402, F401
