Source code for dask.array.image

import os
from glob import glob

try:
    from skimage.io import imread as sk_imread
except (AttributeError, ImportError):
    pass

from ..base import tokenize
from .core import Array


def add_leading_dimension(x):
    return x[None, ...]


[docs]def imread(filename, imread=None, preprocess=None): """Read a stack of images into a dask array Parameters ---------- filename: string A globstring like 'myfile.*.png' imread: function (optional) Optionally provide custom imread function. Function should expect a filename and produce a numpy array. Defaults to ``skimage.io.imread``. preprocess: function (optional) Optionally provide custom function to preprocess the image. Function should expect a numpy array for a single image. Examples -------- >>> from dask.array.image import imread >>> im = imread('2015-*-*.png') # doctest: +SKIP >>> im.shape # doctest: +SKIP (365, 1000, 1000, 3) Returns ------- Dask array of all images stacked along the first dimension. All images will be treated as individual chunks """ imread = imread or sk_imread filenames = sorted(glob(filename)) if not filenames: raise ValueError("No files found under name %s" % filename) name = "imread-%s" % tokenize(filenames, map(os.path.getmtime, filenames)) sample = imread(filenames[0]) if preprocess: sample = preprocess(sample) keys = [(name, i) + (0,) * len(sample.shape) for i in range(len(filenames))] if preprocess: values = [ (add_leading_dimension, (preprocess, (imread, fn))) for fn in filenames ] else: values = [(add_leading_dimension, (imread, fn)) for fn in filenames] dsk = dict(zip(keys, values)) chunks = ((1,) * len(filenames),) + tuple((d,) for d in sample.shape) return Array(dsk, name, chunks, sample.dtype)