forked from 170010011/fr
365 lines
12 KiB
Python
365 lines
12 KiB
Python
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"""
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PIL formats for multiple images.
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"""
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import logging
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import numpy as np
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from .pillow import PillowFormat, ndarray_to_pil, image_as_uint
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logger = logging.getLogger(__name__)
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NeuQuant = None # we can implement this when we need it
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class TIFFFormat(PillowFormat):
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_modes = "i" # arg, why bother; people should use the tiffile version
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_description = "TIFF format (Pillow)"
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class GIFFormat(PillowFormat):
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""" A format for reading and writing static and animated GIF, based
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on Pillow.
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Images read with this format are always RGBA. Currently,
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the alpha channel is ignored when saving RGB images with this
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format.
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Parameters for reading
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----------------------
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None
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Parameters for saving
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---------------------
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loop : int
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The number of iterations. Default 0 (meaning loop indefinitely).
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duration : {float, list}
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The duration (in seconds) of each frame. Either specify one value
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that is used for all frames, or one value for each frame.
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Note that in the GIF format the duration/delay is expressed in
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hundredths of a second, which limits the precision of the duration.
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fps : float
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The number of frames per second. If duration is not given, the
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duration for each frame is set to 1/fps. Default 10.
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palettesize : int
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The number of colors to quantize the image to. Is rounded to
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the nearest power of two. Default 256.
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subrectangles : bool
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If True, will try and optimize the GIF by storing only the
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rectangular parts of each frame that change with respect to the
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previous. Default False.
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"""
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_modes = "iI"
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_description = "Static and animated gif (Pillow)"
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class Reader(PillowFormat.Reader):
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def _open(self, playback=None): # compat with FI format
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return PillowFormat.Reader._open(self)
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class Writer(PillowFormat.Writer):
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def _open(
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self,
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loop=0,
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duration=None,
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fps=10,
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palettesize=256,
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quantizer=0,
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subrectangles=False,
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):
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# Check palettesize
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palettesize = int(palettesize)
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if palettesize < 2 or palettesize > 256:
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raise ValueError("GIF quantize param must be 2..256")
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if palettesize not in [2, 4, 8, 16, 32, 64, 128, 256]:
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palettesize = 2 ** int(np.log2(128) + 0.999)
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logger.warning(
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"Warning: palettesize (%r) modified to a factor of "
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"two between 2-256." % palettesize
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)
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# Duratrion / fps
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if duration is None:
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self._duration = 1.0 / float(fps)
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elif isinstance(duration, (list, tuple)):
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self._duration = [float(d) for d in duration]
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else:
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self._duration = float(duration)
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# loop
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loop = float(loop)
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if loop <= 0 or loop == float("inf"):
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loop = 0
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loop = int(loop)
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# Subrectangles / dispose
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subrectangles = bool(subrectangles)
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self._dispose = 1 if subrectangles else 2
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# The "0" (median cut) quantizer is by far the best
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fp = self.request.get_file()
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self._writer = GifWriter(
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fp, subrectangles, loop, quantizer, int(palettesize)
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)
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def _close(self):
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self._writer.close()
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def _append_data(self, im, meta):
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im = image_as_uint(im, bitdepth=8)
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if im.ndim == 3 and im.shape[-1] == 1:
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im = im[:, :, 0]
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duration = self._duration
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if isinstance(duration, list):
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duration = duration[min(len(duration) - 1, self._writer._count)]
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dispose = self._dispose
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self._writer.add_image(im, duration, dispose)
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return
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intToBin = lambda i: i.to_bytes(2, byteorder="little")
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class GifWriter:
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""" Class that for helping write the animated GIF file. This is based on
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code from images2gif.py (part of visvis). The version here is modified
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to allow streamed writing.
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"""
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def __init__(
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self,
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file,
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opt_subrectangle=True,
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opt_loop=0,
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opt_quantizer=0,
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opt_palette_size=256,
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):
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self.fp = file
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self.opt_subrectangle = opt_subrectangle
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self.opt_loop = opt_loop
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self.opt_quantizer = opt_quantizer
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self.opt_palette_size = opt_palette_size
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self._previous_image = None # as np array
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self._global_palette = None # as bytes
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self._count = 0
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from PIL.GifImagePlugin import getdata
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self.getdata = getdata
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def add_image(self, im, duration, dispose):
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# Prepare image
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im_rect, rect = im, (0, 0)
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if self.opt_subrectangle:
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im_rect, rect = self.getSubRectangle(im)
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im_pil = self.converToPIL(im_rect, self.opt_quantizer, self.opt_palette_size)
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# Get pallette - apparently, this is the 3d element of the header
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# (but it has not always been). Best we've got. Its not the same
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# as im_pil.palette.tobytes().
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from PIL.GifImagePlugin import getheader
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palette = getheader(im_pil)[0][3]
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# Write image
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if self._count == 0:
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self.write_header(im_pil, palette, self.opt_loop)
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self._global_palette = palette
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self.write_image(im_pil, palette, rect, duration, dispose)
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# assert len(palette) == len(self._global_palette)
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# Bookkeeping
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self._previous_image = im
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self._count += 1
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def write_header(self, im, globalPalette, loop):
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# Gather info
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header = self.getheaderAnim(im)
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appext = self.getAppExt(loop)
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# Write
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self.fp.write(header)
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self.fp.write(globalPalette)
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self.fp.write(appext)
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def close(self):
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self.fp.write(";".encode("utf-8")) # end gif
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def write_image(self, im, palette, rect, duration, dispose):
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fp = self.fp
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# Gather local image header and data, using PIL's getdata. That
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# function returns a list of bytes objects, but which parts are
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# what has changed multiple times, so we put together the first
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# parts until we have enough to form the image header.
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data = self.getdata(im)
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imdes = b""
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while data and len(imdes) < 11:
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imdes += data.pop(0)
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assert len(imdes) == 11
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# Make image descriptor suitable for using 256 local color palette
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lid = self.getImageDescriptor(im, rect)
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graphext = self.getGraphicsControlExt(duration, dispose)
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# Write local header
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if (palette != self._global_palette) or (dispose != 2):
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# Use local color palette
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fp.write(graphext)
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fp.write(lid) # write suitable image descriptor
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fp.write(palette) # write local color table
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fp.write(b"\x08") # LZW minimum size code
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else:
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# Use global color palette
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fp.write(graphext)
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fp.write(imdes) # write suitable image descriptor
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# Write image data
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for d in data:
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fp.write(d)
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def getheaderAnim(self, im):
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""" Get animation header. To replace PILs getheader()[0]
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"""
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bb = b"GIF89a"
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bb += intToBin(im.size[0])
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bb += intToBin(im.size[1])
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bb += b"\x87\x00\x00"
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return bb
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def getImageDescriptor(self, im, xy=None):
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""" Used for the local color table properties per image.
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Otherwise global color table applies to all frames irrespective of
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whether additional colors comes in play that require a redefined
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palette. Still a maximum of 256 color per frame, obviously.
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Written by Ant1 on 2010-08-22
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Modified by Alex Robinson in Janurari 2011 to implement subrectangles.
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"""
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# Defaule use full image and place at upper left
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if xy is None:
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xy = (0, 0)
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# Image separator,
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bb = b"\x2C"
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# Image position and size
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bb += intToBin(xy[0]) # Left position
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bb += intToBin(xy[1]) # Top position
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bb += intToBin(im.size[0]) # image width
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bb += intToBin(im.size[1]) # image height
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# packed field: local color table flag1, interlace0, sorted table0,
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# reserved00, lct size111=7=2^(7 + 1)=256.
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bb += b"\x87"
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# LZW minimum size code now comes later, begining of [imagedata] blocks
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return bb
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def getAppExt(self, loop):
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""" Application extension. This part specifies the amount of loops.
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If loop is 0 or inf, it goes on infinitely.
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"""
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if loop == 1:
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return b""
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if loop == 0:
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loop = 2 ** 16 - 1
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bb = b""
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if loop != 0: # omit the extension if we would like a nonlooping gif
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bb = b"\x21\xFF\x0B" # application extension
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bb += b"NETSCAPE2.0"
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bb += b"\x03\x01"
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bb += intToBin(loop)
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bb += b"\x00" # end
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return bb
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def getGraphicsControlExt(self, duration=0.1, dispose=2):
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""" Graphics Control Extension. A sort of header at the start of
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each image. Specifies duration and transparancy.
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Dispose
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-------
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* 0 - No disposal specified.
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* 1 - Do not dispose. The graphic is to be left in place.
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* 2 - Restore to background color. The area used by the graphic
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must be restored to the background color.
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* 3 - Restore to previous. The decoder is required to restore the
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area overwritten by the graphic with what was there prior to
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rendering the graphic.
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* 4-7 -To be defined.
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"""
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bb = b"\x21\xF9\x04"
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bb += chr((dispose & 3) << 2).encode("utf-8")
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# low bit 1 == transparency,
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# 2nd bit 1 == user input , next 3 bits, the low two of which are used,
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# are dispose.
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bb += intToBin(int(duration * 100 + 0.5)) # in 100th of seconds
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bb += b"\x00" # no transparant color
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bb += b"\x00" # end
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return bb
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def getSubRectangle(self, im):
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""" Calculate the minimal rectangle that need updating. Returns
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a two-element tuple containing the cropped image and an x-y tuple.
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Calculating the subrectangles takes extra time, obviously. However,
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if the image sizes were reduced, the actual writing of the GIF
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goes faster. In some cases applying this method produces a GIF faster.
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"""
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# Cannot do subrectangle for first image
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if self._count == 0:
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return im, (0, 0)
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prev = self._previous_image
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# Get difference, sum over colors
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diff = np.abs(im - prev)
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if diff.ndim == 3:
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diff = diff.sum(2)
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# Get begin and end for both dimensions
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X = np.argwhere(diff.sum(0))
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Y = np.argwhere(diff.sum(1))
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# Get rect coordinates
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if X.size and Y.size:
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x0, x1 = int(X[0]), int(X[-1] + 1)
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y0, y1 = int(Y[0]), int(Y[-1] + 1)
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else: # No change ... make it minimal
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x0, x1 = 0, 2
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y0, y1 = 0, 2
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return im[y0:y1, x0:x1], (x0, y0)
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def converToPIL(self, im, quantizer, palette_size=256):
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"""Convert image to Paletted PIL image.
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PIL used to not do a very good job at quantization, but I guess
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this has improved a lot (at least in Pillow). I don't think we need
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neuqant (and we can add it later if we really want).
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"""
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im_pil = ndarray_to_pil(im, "gif")
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if quantizer in ("nq", "neuquant"):
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# NeuQuant algorithm
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nq_samplefac = 10 # 10 seems good in general
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im_pil = im_pil.convert("RGBA") # NQ assumes RGBA
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nqInstance = NeuQuant(im_pil, nq_samplefac) # Learn colors
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im_pil = nqInstance.quantize(im_pil, colors=palette_size)
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elif quantizer in (0, 1, 2):
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# Adaptive PIL algorithm
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if quantizer == 2:
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im_pil = im_pil.convert("RGBA")
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else:
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im_pil = im_pil.convert("RGB")
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im_pil = im_pil.quantize(colors=palette_size, method=quantizer)
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else:
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raise ValueError("Invalid value for quantizer: %r" % quantizer)
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return im_pil
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