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| # 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 annotations | |
| import re | |
| from . import Image, _imagingmorph | |
| 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 | |
| class LutBuilder: | |
| """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: list[str] | None = None, op_name: str | None = None | |
| ) -> None: | |
| if patterns is not None: | |
| self.patterns = patterns | |
| else: | |
| self.patterns = [] | |
| self.lut: bytearray | None = 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: | |
| msg = "Unknown pattern " + op_name + "!" | |
| raise Exception(msg) | |
| self.patterns = known_patterns[op_name] | |
| def add_patterns(self, patterns: list[str]) -> None: | |
| self.patterns += patterns | |
| def build_default_lut(self) -> None: | |
| symbols = [0, 1] | |
| m = 1 << 4 # pos of current pixel | |
| self.lut = bytearray(symbols[(i & m) > 0] for i in range(LUT_SIZE)) | |
| def get_lut(self) -> bytearray | None: | |
| return self.lut | |
| def _string_permute(self, pattern: str, permutation: list[int]) -> str: | |
| """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: str, options: str, basic_result: int | |
| ) -> list[tuple[str, int]]: | |
| """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[:n]: | |
| patterns.append((self._string_permute(pattern, MIRROR_MATRIX), res)) | |
| # negate | |
| if "N" in options: | |
| n = len(patterns) | |
| for pattern, res in patterns[: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 | |
| def build_lut(self) -> bytearray: | |
| """Compile all patterns into a morphology lut. | |
| TBD :Build based on (file) morphlut:modify_lut | |
| """ | |
| self.build_default_lut() | |
| assert self.lut is not None | |
| 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: | |
| msg = 'Syntax error in pattern "' + p + '"' | |
| raise Exception(msg) | |
| 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 | |
| compiled_patterns = [] | |
| for pattern in patterns: | |
| p = pattern[0].replace(".", "X").replace("X", "[01]") | |
| compiled_patterns.append((re.compile(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 pattern, r in compiled_patterns: | |
| if pattern.match(bitpattern): | |
| self.lut[i] = [0, 1][r] | |
| return self.lut | |
| class MorphOp: | |
| """A class for binary morphological operators""" | |
| def __init__( | |
| self, | |
| lut: bytearray | None = None, | |
| op_name: str | None = None, | |
| patterns: list[str] | None = None, | |
| ) -> 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() | |
| def apply(self, image: Image.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: | |
| msg = "No operator loaded" | |
| raise Exception(msg) | |
| if image.mode != "L": | |
| msg = "Image mode must be L" | |
| raise ValueError(msg) | |
| outimage = Image.new(image.mode, image.size, None) | |
| count = _imagingmorph.apply(bytes(self.lut), image.im.id, outimage.im.id) | |
| return count, outimage | |
| def match(self, image: Image.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: | |
| msg = "No operator loaded" | |
| raise Exception(msg) | |
| if image.mode != "L": | |
| msg = "Image mode must be L" | |
| raise ValueError(msg) | |
| return _imagingmorph.match(bytes(self.lut), image.im.id) | |
| def get_on_pixels(self, image: Image.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": | |
| msg = "Image mode must be L" | |
| raise ValueError(msg) | |
| return _imagingmorph.get_on_pixels(image.im.id) | |
| def load_lut(self, filename: str) -> None: | |
| """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 | |
| msg = "Wrong size operator file!" | |
| raise Exception(msg) | |
| def save_lut(self, filename: str) -> None: | |
| """Save an operator to an mrl file""" | |
| if self.lut is None: | |
| msg = "No operator loaded" | |
| raise Exception(msg) | |
| with open(filename, "wb") as f: | |
| f.write(self.lut) | |
| def set_lut(self, lut: bytearray | None) -> None: | |
| """Set the lut from an external source""" | |
| self.lut = lut | |