ImageMorph module

The ImageMorph module allows morphology operators (“MorphOp”) to be applied to 1 or L mode images:

from PIL import Image, ImageMorph
img = Image.open("Tests/images/hopper.bw")
mop = ImageMorph.MorphOp(op_name="erosion4")
count, imgOut = mop.apply(img)
imgOut.show()

In addition to applying operators, you can also analyse images.

You can inspect an image in isolation to determine which pixels are non-empty:

print(mop.get_on_pixels(img))  # [(0, 0), (1, 0), (2, 0), ...]

Or you can retrieve a list of pixels that match the operator. This is the number of pixels that will be non-empty after the operator is applied:

coords = mop.match(img)
print(coords)  # [(17, 1), (18, 1), (34, 1), ...]
print(len(coords))  # 550

imgOut = mop.apply(img)[1]
print(len(mop.get_on_pixels(imgOut)))  # 550

If you would like more customized operators, you can pass patterns to the MorphOp class:

mop = ImageMorph.MorphOp(patterns=["1:(... ... ...)->0", "4:(00. 01. ...)->1"])

Or you can pass lookup table (“LUT”) data directly. This LUT data can be constructed with the LutBuilder:

builder = ImageMorph.LutBuilder()
mop = ImageMorph.MorphOp(lut=builder.build_lut())

class PIL.ImageMorph.LutBuilder(patterns: list[str] | None = None, op_name: str | None = None)

Bases: 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()

add_patterns(patterns: list[str]) → None

Append to list of patterns.

Parameters:

patterns – Additional patterns.

build_default_lut() → bytearray

Set the current LUT, and return it.

This is the default LUT that patterns will be applied against when building.

build_lut() → bytearray

Compile all patterns into a morphology LUT, and return it.

This is the data to be passed into MorphOp.

get_lut() → bytearray | None

Returns the current LUT

class PIL.ImageMorph.MorphOp(lut: bytearray | None = None, op_name: str | None = None, patterns: list[str] | None = None)

Bases: object

A class for binary morphological operators

apply(image: Image) → tuple[int, Image]

Run a single morphological operation on an image.

Returns a tuple of the number of changed pixels and the morphed image.

Parameters:

image – A 1-mode or L-mode image.

Raises:

• Exception – If the current operator is None.

• ValueError – If the image is not 1 or L mode.

get_on_pixels(image: Image) → list[tuple[int, int]]

Get a list of all turned on pixels in a 1 or L mode image.

Returns a list of tuples of (x,y) coordinates of all non-empty pixels. See Coordinate system.

Parameters:

image – A 1-mode or L-mode image.

Raises:

ValueError – If the image is not 1 or L mode.

load_lut(filename: str) → None

Load an operator from an mrl file

Parameters:

filename – The file to read from.

Raises:

Exception – If the length of the file data is not 512.

match(image: Image) → list[tuple[int, int]]

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 Coordinate system.

Parameters:

image – A 1-mode or L-mode image.

Raises:

• Exception – If the current operator is None.

• ValueError – If the image is not 1 or L mode.

save_lut(filename: str) → None

Save an operator to an mrl file.

Parameters:

filename – The destination file.

Raises:

Exception – If the current operator is None.

set_lut(lut: bytearray | None) → None

Set the LUT from an external source

Parameters:

lut – A new LUT.