Pillow/PIL/ImagePalette.py

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#
# The Python Imaging Library.
# $Id$
#
# image palette object
#
# History:
# 1996-03-11 fl Rewritten.
# 1997-01-03 fl Up and running.
# 1997-08-23 fl Added load hack
# 2001-04-16 fl Fixed randint shadow bug in random()
#
# Copyright (c) 1997-2001 by Secret Labs AB
# Copyright (c) 1996-1997 by Fredrik Lundh
#
# See the README file for information on usage and redistribution.
#
import array
from . import ImageColor, GimpPaletteFile, GimpGradientFile, PaletteFile
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class ImagePalette(object):
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"""
Color palette for palette mapped images
:param mode: The mode to use for the Palette. See:
:ref:`concept-modes`. Defaults to "RGB"
:param palette: An optional palette. If given, it must be a bytearray,
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an array or a list of ints between 0-255 and of length ``size``
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times the number of colors in ``mode``. The list must be aligned
by channel (All R values must be contiguous in the list before G
and B values.) Defaults to 0 through 255 per channel.
:param size: An optional palette size. If given, it cannot be equal to
or greater than 256. Defaults to 0.
"""
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def __init__(self, mode="RGB", palette=None, size=0):
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self.mode = mode
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self.rawmode = None # if set, palette contains raw data
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self.palette = palette or bytearray(range(256))*len(self.mode)
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self.colors = {}
self.dirty = None
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if ((size == 0 and len(self.mode)*256 != len(self.palette)) or
(size != 0 and size != len(self.palette))):
raise ValueError("wrong palette size")
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def copy(self):
new = ImagePalette()
new.mode = self.mode
new.rawmode = self.rawmode
if self.palette is not None:
new.palette = self.palette[:]
new.colors = self.colors.copy()
new.dirty = self.dirty
return new
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def getdata(self):
"""
Get palette contents in format suitable # for the low-level
``im.putpalette`` primitive.
.. warning:: This method is experimental.
"""
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if self.rawmode:
return self.rawmode, self.palette
return self.mode + ";L", self.tobytes()
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def tobytes(self):
"""Convert palette to bytes.
.. warning:: This method is experimental.
"""
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if self.rawmode:
raise ValueError("palette contains raw palette data")
if isinstance(self.palette, bytes):
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return self.palette
arr = array.array("B", self.palette)
if hasattr(arr, 'tobytes'):
return arr.tobytes()
return arr.tostring()
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# Declare tostring as an alias for tobytes
tostring = tobytes
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def getcolor(self, color):
"""Given an rgb tuple, allocate palette entry.
.. warning:: This method is experimental.
"""
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if self.rawmode:
raise ValueError("palette contains raw palette data")
if isinstance(color, tuple):
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try:
return self.colors[color]
except KeyError:
# allocate new color slot
if isinstance(self.palette, bytes):
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self.palette = bytearray(self.palette)
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index = len(self.colors)
if index >= 256:
raise ValueError("cannot allocate more than 256 colors")
self.colors[color] = index
self.palette[index] = color[0]
self.palette[index+256] = color[1]
self.palette[index+512] = color[2]
self.dirty = 1
return index
else:
raise ValueError("unknown color specifier: %r" % color)
def save(self, fp):
"""Save palette to text file.
.. warning:: This method is experimental.
"""
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if self.rawmode:
raise ValueError("palette contains raw palette data")
if isinstance(fp, str):
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fp = open(fp, "w")
fp.write("# Palette\n")
fp.write("# Mode: %s\n" % self.mode)
for i in range(256):
fp.write("%d" % i)
for j in range(i*len(self.mode), (i+1)*len(self.mode)):
try:
fp.write(" %d" % self.palette[j])
except IndexError:
fp.write(" 0")
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fp.write("\n")
fp.close()
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# --------------------------------------------------------------------
# Internal
def raw(rawmode, data):
palette = ImagePalette()
palette.rawmode = rawmode
palette.palette = data
palette.dirty = 1
return palette
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# --------------------------------------------------------------------
# Factories
def make_linear_lut(black, white):
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lut = []
if black == 0:
for i in range(256):
lut.append(white*i//255)
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else:
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raise NotImplementedError # FIXME
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return lut
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def make_gamma_lut(exp):
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lut = []
for i in range(256):
lut.append(int(((i / 255.0) ** exp) * 255.0 + 0.5))
return lut
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def negative(mode="RGB"):
palette = list(range(256))
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palette.reverse()
return ImagePalette(mode, palette * len(mode))
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def random(mode="RGB"):
from random import randint
palette = []
for i in range(256*len(mode)):
palette.append(randint(0, 255))
return ImagePalette(mode, palette)
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def sepia(white="#fff0c0"):
r, g, b = ImageColor.getrgb(white)
r = make_linear_lut(0, r)
g = make_linear_lut(0, g)
b = make_linear_lut(0, b)
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return ImagePalette("RGB", r + g + b)
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def wedge(mode="RGB"):
return ImagePalette(mode, list(range(256)) * len(mode))
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def load(filename):
# FIXME: supports GIMP gradients only
with open(filename, "rb") as fp:
for paletteHandler in [
GimpPaletteFile.GimpPaletteFile,
GimpGradientFile.GimpGradientFile,
PaletteFile.PaletteFile
]:
try:
fp.seek(0)
lut = paletteHandler(fp).getpalette()
if lut:
break
except (SyntaxError, ValueError):
# import traceback
# traceback.print_exc()
pass
else:
raise IOError("cannot load palette")
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return lut # data, rawmode