Source code for large_image.tilesource.stylefuncs

# This module contains functions for use in styles

import numpy

[docs]def maskPixelValues(image, context, values=None, negative=None, positive=None): """ This is a style utility function that returns a black-and-white 8-bit image where the image is white if the pixel of the source image is in a list of values and black otherwise. The values is a list where each entry can either be a tuple the same length as the band dimension of the output image or a single value which is handled as 0xBBGGRR. :param image: a numpy array of Y, X, Bands. :param context: the style context. context.image is the source image :param values: an array of values, each of which is either an array of the same number of bands as the source image or a single value of the form 0xBBGGRR assuming uint8 data. :param negative: None to use [0, 0, 0, 255], or an RGBA uint8 value for pixels not in the value list. :param positive: None to use [255, 255, 255, 0], or an RGBA uint8 value for pixels in the value list. :returns: an RGBA numpy image which is exactly black or transparent white. """ src = context.image mask = numpy.full(src.shape[:2], False) for val in values: if not isinstance(val, (list, tuple)): if src.shape[-1] == 1: val = [val] else: val = [val % 256, val // 256 % 256, val // 65536 % 256] val = (list(val) + [255] * src.shape[2])[:src.shape[2]] match = numpy.array(val) mask = mask | (src == match).all(axis=-1) image[mask != True] = negative or [0, 0, 0, 255] # noqa E712 image[mask] = positive or [255, 255, 255, 0] image = image.astype(numpy.uint8) return image