"""
Wraps all the functions related to applying thresholding techniques to an image.
"""
import cv2
import numpy as np
__authors__ = "Stephan Nell, Nicolai van Niekerk"
__copyright__ = "Copyright 2017, Java the Hutts"
__license__ = "BSD"
__maintainer__ = "Stephan Nell"
__email__ = "nellstephanj@gmail.com"
__status__ = "Development"
[docs]class ThresholdingManager:
"""
The Thresholding manager is responsible for applying the different types of thresholding techniques.
"""
def __init__(self, thresholding_type):
"""
Initialise Thresholding manager.
Args:
thresholding_type (str): Indicates the type of thresholding that
should be applied.
Raises:
TypeError: If a parameter is passed that is not of type String.
NameError: If the thresholding type is not Adaptive or Otsu.
Returns:
None
"""
if not isinstance(thresholding_type, str):
raise TypeError(
'Bad type for arg thresholding_type - expected string. Received type "%s".' %
type(thresholding_type).__name__
)
if thresholding_type == "adaptive":
self.thresholding_type = thresholding_type
elif thresholding_type == "otsu":
self.thresholding_type = thresholding_type
else:
raise NameError('Invalid Thresholding Selection! Try "adaptive" or "otsu" thresholding types.')
[docs] def apply(self, image):
"""
This performs the thresholding based on the predefined technique.
Args:
image: The image to which the thresholding must be applied.
Raises:
NameError: If invalid thresholding type is provided. i.e. Adaptive or Otsu.
Returns:
obj:'OpenCV image': The threshold image.
"""
if self.thresholding_type == "adaptive":
return self.adaptiveThresholding(image)
elif self.thresholding_type == "otsu":
return self.otsuThresholding(image)
else:
raise NameError('Invalid Thresholding Selection! Could not Apply Thresholding')
[docs] @staticmethod
def adaptiveThresholding(image):
"""
This function applies a simple adaptive thresholding to the image passed.
Args:
image (:obj:'OpenCV image'): Image to which thresholding should be applied.
Raises:
TypeError: If a parameter is passed that is not of type Numpy array.
Returns:
obj:'OpenCV image': The Threshold image.
"""
if not isinstance(image, np.ndarray):
raise TypeError(
'Bad type for arg image - expected image in numpy array. Received type "%s".' %
type(image).__name__
)
return cv2.adaptiveThreshold(image, 255, cv2.ADAPTIVE_THRESH_GAUSSIAN_C, cv2.THRESH_BINARY_INV, 25, 10)
[docs] @staticmethod
def otsuThresholding(image):
"""
This function applies a simple Binary Inverse Otso thresholding to the image passed.
Args:
image (:obj:'OpenCV image'): Image to which thresholding should be applied.
Raises:
TypeError: If a parameter is passed that is not of type Numpy array.
Returns:
obj:'OpenCV image': The Threshold image.
"""
if not isinstance(image, np.ndarray):
raise TypeError(
'Bad type for arg image - expected image in numpy array. Received type "%s".' %
type(image).__name__
)
(_, threshInv) = cv2.threshold(image, 0, 255, cv2.THRESH_BINARY_INV | cv2.THRESH_OTSU)
return threshInv