Distance Transform¶

Perform distance transform on binary image

plantcv.distance_transform(bin_img, distance_type, mask_size)

returns distance transformed image normalized between 0 and 1

• Parameters:

  • bin_img - Binary image data
  • distance_type - Type of distance. It can be CV_DIST_L1, CV_DIST_L2 , or CV_DIST_C which are 1,2 and 3 respectively.
  • mask_size - Size of the distance transform mask. It can be 3, 5, or CV_DIST_MASK_PRECISE (the latter option is only supported by the first function). In case of the CV_DIST_L1 or CV_DIST_C distance type, the parameter is forced to 3 because a 3 by 3 mask gives the same result as 5 by 5 or any larger aperture.

• Context:

  • Used to perform object segmentation via thresholding and marker-aided watershed segmentation.
• Example use:
  • See below.

Input binary image

from plantcv import plantcv as pcv

# Set global debug behavior to None (default), "print" (to file), or "plot" (Jupyter Notebooks or X11)
pcv.params.debug = "print"

# Perform dilation
# Results in addition of pixels to the boundary of object
distance_transform_img = pcv.distance_transform(mask, 1, 3)

Image after distance transform