Source code for PIL.ImagePalette

#
# 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


[docs]class ImagePalette(object): """ 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, an array or a list of ints between 0-255 and of length ``size`` 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. """ def __init__(self, mode="RGB", palette=None, size=0): self.mode = mode self.rawmode = None # if set, palette contains raw data self.palette = palette or bytearray(range(256)) * len(self.mode) self.colors = {} self.dirty = None if (size == 0 and len(self.mode) * 256 != len(self.palette)) or ( size != 0 and size != len(self.palette) ): raise ValueError("wrong palette size") 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
[docs] def getdata(self): """ Get palette contents in format suitable for the low-level ``im.putpalette`` primitive. .. warning:: This method is experimental. """ if self.rawmode: return self.rawmode, self.palette return self.mode + ";L", self.tobytes()
[docs] def tobytes(self): """Convert palette to bytes. .. warning:: This method is experimental. """ if self.rawmode: raise ValueError("palette contains raw palette data") if isinstance(self.palette, bytes): return self.palette arr = array.array("B", self.palette) if hasattr(arr, "tobytes"): return arr.tobytes() return arr.tostring()
# Declare tostring as an alias for tobytes tostring = tobytes
[docs] def getcolor(self, color): """Given an rgb tuple, allocate palette entry. .. warning:: This method is experimental. """ if self.rawmode: raise ValueError("palette contains raw palette data") if isinstance(color, tuple): try: return self.colors[color] except KeyError: # allocate new color slot if isinstance(self.palette, bytes): self.palette = bytearray(self.palette) 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)
[docs] def save(self, fp): """Save palette to text file. .. warning:: This method is experimental. """ if self.rawmode: raise ValueError("palette contains raw palette data") if isinstance(fp, str): 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") fp.write("\n") fp.close()
# -------------------------------------------------------------------- # Internal def raw(rawmode, data): palette = ImagePalette() palette.rawmode = rawmode palette.palette = data palette.dirty = 1 return palette # -------------------------------------------------------------------- # Factories def make_linear_lut(black, white): lut = [] if black == 0: for i in range(256): lut.append(white * i // 255) else: raise NotImplementedError # FIXME return lut def make_gamma_lut(exp): lut = [] for i in range(256): lut.append(int(((i / 255.0) ** exp) * 255.0 + 0.5)) return lut def negative(mode="RGB"): palette = list(range(256)) palette.reverse() return ImagePalette(mode, palette * len(mode)) 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) 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) return ImagePalette("RGB", r + g + b) def wedge(mode="RGB"): return ImagePalette(mode, list(range(256)) * len(mode)) 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") return lut # data, rawmode