ITK Python interop

itkwasm can be used with native itk Python bindings.

Both packages support common Python dictionary representations of the data structures used on interfaces. The non-dictionary types are more convenient to work with directly and provide strong typing for function calls.

Convert from itkwasm to itk

To convert from an itkwasm dataclass interface type to a native itk Python type, first convert the itkwasm type to a dictionary, then use the itk.<type>_from_dict function. Example:

from itkwasm import Image
from dataclasses import asdict
itkwasm_image = Image()
image_dict = asdict(itkwasm_image)

import itk
itk_image = itk.image_from_dict(image_dict)

Convert from itk to itkwasm

To convert from a native itk Python type to an itkwasm dataclass interface type, first convert the itkwasm type to a dictionary with itk.dict_from_<type>, then pass the dictionary as keyword arguments to itkwasm constructor with the ** operator. Example:

import itk
# Create an itk.Image
itk_image = itk.Image.New()
itk_image.SetRegions([8,8])
itk_image.Allocate()
image_dict = itk.dict_from_image(itk_image)

from itkwasm import Image
itkwasm_image = Image(**image_dict)

itkwasm file formats

itkwasm provides file formats corresponding to its interface types. These file formats keep wasm module sizes tiny, enable efficient and one-to-one serialization, assist with debugging, and bridge with Web3 technologies.

The file extensions for these formats are .iwi and .iwm for images and mesh-like data, respectively. When written, these will output directories with an index.json file and raw binary files. When .iwi.cbor or .iwm.cbor extensions are used, a single CBOR file is created.

These file formats can also be used with native ITK Python.

Install the binary Python package:

pip install itk-webassemblyinterface

Then use with itk.imread, itk.imwrite, itk.meshread, itk.meshwrite. Example:

import itk

image = itk.imread('cthead1.png')
itk.imwrite(image, 'cthead1.iwi')
itk.imwrite(image, 'cthead1.iwi.cbor')

mesh = itk.meshread('cow.vtk')
itk.meshwrite(mesh, 'cow.iwm')
itk.meshwrite(mesh, 'cow.iwm.cbor')