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
import warnings

from . import GimpGradientFile, GimpPaletteFile, ImageColor, PaletteFile


[docs]class ImagePalette: """ 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. The list must consist of all channels for one color followed by the next color (e.g. RGBRGBRGB). Defaults to an empty palette. :param size: An optional palette size. If given, an error is raised if ``palette`` is not of equal length. """ 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() self.dirty = None if size != 0: warnings.warn( "The size parameter is deprecated and will be removed in Pillow 10 " "(2023-01-02).", DeprecationWarning, ) if size != len(self.palette): raise ValueError("wrong palette size") @property def palette(self): return self._palette @palette.setter def palette(self, palette): self._palette = palette mode_len = len(self.mode) self.colors = {} for i in range(0, len(self.palette), mode_len): color = tuple(self.palette[i : i + mode_len]) if color in self.colors: continue self.colors[color] = i // mode_len def copy(self): new = ImagePalette() new.mode = self.mode new.rawmode = self.rawmode if self.palette is not None: new.palette = self.palette[:] 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, 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) return arr.tobytes()
# Declare tostring as an alias for tobytes tostring = tobytes
[docs] def getcolor(self, color, image=None): """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): if self.mode == "RGB": if len(color) == 4 and color[3] == 255: color = color[:3] elif self.mode == "RGBA": if len(color) == 3: color += (255,) try: return self.colors[color] except KeyError as e: # allocate new color slot if not isinstance(self.palette, bytearray): self._palette = bytearray(self.palette) index = len(self.palette) // 3 special_colors = () if image: special_colors = ( image.info.get("background"), image.info.get("transparency"), ) while index in special_colors: index += 1 if index >= 256: if image: # Search for an unused index for i, count in reversed(list(enumerate(image.histogram()))): if count == 0 and i not in special_colors: index = i break if index >= 256: raise ValueError("cannot allocate more than 256 colors") from e self.colors[color] = index if index * 3 < len(self.palette): self._palette = ( self.palette[: index * 3] + bytes(color) + self.palette[index * 3 + 3 :] ) else: self._palette += bytes(color) self.dirty = 1 return index else: raise ValueError(f"unknown color specifier: {repr(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(f"# Mode: {self.mode}\n") for i in range(256): fp.write(f"{i}") for j in range(i * len(self.mode), (i + 1) * len(self.mode)): try: fp.write(f" {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 * len(mode))) palette.reverse() return ImagePalette(mode, [i // len(mode) for i in palette]) 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"): bands = [make_linear_lut(0, band) for band in ImageColor.getrgb(white)] return ImagePalette("RGB", [bands[i % 3][i // 3] for i in range(256 * 3)]) def wedge(mode="RGB"): palette = list(range(256 * len(mode))) return ImagePalette(mode, [i // len(mode) for i in palette]) 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 OSError("cannot load palette") return lut # data, rawmode