Otsu Threshold¶

Creates a binary image from a gray image based on the threshold values.

otsu_auto_threshold(img, maxValue, object_type, device, debug=None)

returns device, thresholded image

• Parameters:
  • img - grayscale img object
  • maxValue - value to apply above threshold (255 = white)
  • objecttype - 'light' or 'dark', is target image light or dark?
  • device- Counter for image processing steps
  • debug- None, "print", or "plot". Print = save to file, Plot = print to screen. Default = None
• Context:
  • Used to help differentiate plant and background

Grayscale image (green-magenta channel)

import plantcv as pcv

# Create binary image from a gray image based on threshold values. Targeting light objects in the image.
device, threshold_light = pcv.otsu_auto_threshold(img, 255, 'dark', device, debug="print")

Thresholded image

Grayscale image (blue-yellow channel)

import plantcv as pcv

# Create binary image from a gray image based on threshold values. Targeting dark objects in the image.
device, threshold_dark = pcv.otsu_auto_threshold(img1, 255, 'light', device, debug="print")

Thresholded image (inverse)