Source code for PIL.ImageMorph

# A binary morphology add-on for the Python Imaging Library
#
# History:
#   2014-06-04 Initial version.
#
# Copyright (c) 2014 Dov Grobgeld <dov.grobgeld@gmail.com>

from __future__ import print_function

from . import Image, _imagingmorph
import re

LUT_SIZE = 1 << 9

# fmt: off
ROTATION_MATRIX = [
    6, 3, 0,
    7, 4, 1,
    8, 5, 2,
]
MIRROR_MATRIX = [
    2, 1, 0,
    5, 4, 3,
    8, 7, 6,
]
# fmt: on


[docs]class LutBuilder(object): """A class for building a MorphLut from a descriptive language The input patterns is a list of a strings sequences like these:: 4:(... .1. 111)->1 (whitespaces including linebreaks are ignored). The option 4 describes a series of symmetry operations (in this case a 4-rotation), the pattern is described by: - . or X - Ignore - 1 - Pixel is on - 0 - Pixel is off The result of the operation is described after "->" string. The default is to return the current pixel value, which is returned if no other match is found. Operations: - 4 - 4 way rotation - N - Negate - 1 - Dummy op for no other operation (an op must always be given) - M - Mirroring Example:: lb = LutBuilder(patterns = ["4:(... .1. 111)->1"]) lut = lb.build_lut() """ def __init__(self, patterns=None, op_name=None): if patterns is not None: self.patterns = patterns else: self.patterns = [] self.lut = None if op_name is not None: known_patterns = { "corner": ["1:(... ... ...)->0", "4:(00. 01. ...)->1"], "dilation4": ["4:(... .0. .1.)->1"], "dilation8": ["4:(... .0. .1.)->1", "4:(... .0. ..1)->1"], "erosion4": ["4:(... .1. .0.)->0"], "erosion8": ["4:(... .1. .0.)->0", "4:(... .1. ..0)->0"], "edge": [ "1:(... ... ...)->0", "4:(.0. .1. ...)->1", "4:(01. .1. ...)->1", ], } if op_name not in known_patterns: raise Exception("Unknown pattern " + op_name + "!") self.patterns = known_patterns[op_name]
[docs] def add_patterns(self, patterns): self.patterns += patterns
[docs] def build_default_lut(self): symbols = [0, 1] m = 1 << 4 # pos of current pixel self.lut = bytearray(symbols[(i & m) > 0] for i in range(LUT_SIZE))
[docs] def get_lut(self): return self.lut
def _string_permute(self, pattern, permutation): """string_permute takes a pattern and a permutation and returns the string permuted according to the permutation list. """ assert len(permutation) == 9 return "".join(pattern[p] for p in permutation) def _pattern_permute(self, basic_pattern, options, basic_result): """pattern_permute takes a basic pattern and its result and clones the pattern according to the modifications described in the $options parameter. It returns a list of all cloned patterns.""" patterns = [(basic_pattern, basic_result)] # rotations if "4" in options: res = patterns[-1][1] for i in range(4): patterns.append( (self._string_permute(patterns[-1][0], ROTATION_MATRIX), res) ) # mirror if "M" in options: n = len(patterns) for pattern, res in patterns[0:n]: patterns.append((self._string_permute(pattern, MIRROR_MATRIX), res)) # negate if "N" in options: n = len(patterns) for pattern, res in patterns[0:n]: # Swap 0 and 1 pattern = pattern.replace("0", "Z").replace("1", "0").replace("Z", "1") res = 1 - int(res) patterns.append((pattern, res)) return patterns
[docs] def build_lut(self): """Compile all patterns into a morphology lut. TBD :Build based on (file) morphlut:modify_lut """ self.build_default_lut() patterns = [] # Parse and create symmetries of the patterns strings for p in self.patterns: m = re.search(r"(\w*):?\s*\((.+?)\)\s*->\s*(\d)", p.replace("\n", "")) if not m: raise Exception('Syntax error in pattern "' + p + '"') options = m.group(1) pattern = m.group(2) result = int(m.group(3)) # Get rid of spaces pattern = pattern.replace(" ", "").replace("\n", "") patterns += self._pattern_permute(pattern, options, result) # compile the patterns into regular expressions for speed for i, pattern in enumerate(patterns): p = pattern[0].replace(".", "X").replace("X", "[01]") p = re.compile(p) patterns[i] = (p, pattern[1]) # Step through table and find patterns that match. # Note that all the patterns are searched. The last one # caught overrides for i in range(LUT_SIZE): # Build the bit pattern bitpattern = bin(i)[2:] bitpattern = ("0" * (9 - len(bitpattern)) + bitpattern)[::-1] for p, r in patterns: if p.match(bitpattern): self.lut[i] = [0, 1][r] return self.lut
[docs]class MorphOp(object): """A class for binary morphological operators""" def __init__(self, lut=None, op_name=None, patterns=None): """Create a binary morphological operator""" self.lut = lut if op_name is not None: self.lut = LutBuilder(op_name=op_name).build_lut() elif patterns is not None: self.lut = LutBuilder(patterns=patterns).build_lut()
[docs] def apply(self, image): """Run a single morphological operation on an image Returns a tuple of the number of changed pixels and the morphed image""" if self.lut is None: raise Exception("No operator loaded") if image.mode != "L": raise Exception("Image must be binary, meaning it must use mode L") outimage = Image.new(image.mode, image.size, None) count = _imagingmorph.apply(bytes(self.lut), image.im.id, outimage.im.id) return count, outimage
[docs] def match(self, image): """Get a list of coordinates matching the morphological operation on an image. Returns a list of tuples of (x,y) coordinates of all matching pixels. See :ref:`coordinate-system`.""" if self.lut is None: raise Exception("No operator loaded") if image.mode != "L": raise Exception("Image must be binary, meaning it must use mode L") return _imagingmorph.match(bytes(self.lut), image.im.id)
[docs] def get_on_pixels(self, image): """Get a list of all turned on pixels in a binary image Returns a list of tuples of (x,y) coordinates of all matching pixels. See :ref:`coordinate-system`.""" if image.mode != "L": raise Exception("Image must be binary, meaning it must use mode L") return _imagingmorph.get_on_pixels(image.im.id)
[docs] def load_lut(self, filename): """Load an operator from an mrl file""" with open(filename, "rb") as f: self.lut = bytearray(f.read()) if len(self.lut) != LUT_SIZE: self.lut = None raise Exception("Wrong size operator file!")
[docs] def save_lut(self, filename): """Save an operator to an mrl file""" if self.lut is None: raise Exception("No operator loaded") with open(filename, "wb") as f: f.write(self.lut)
[docs] def set_lut(self, lut): """Set the lut from an external source""" self.lut = lut