Coverage for image_preprocessing/thresholding_manager.py : 82%

import cv2 

import numpy as np 

class ThresholdingManager: 

""" 

The Thresholding manager is responsible for applying the different types of thresholding techniques. 

""" 

def __init__(self, thresholding_type): 

""" 

Initialise Thresholding manager. 

Authors(s): 

Nicolai van Niekerk, Stephan Nell 

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.') 

def apply(self, image): 

""" 

This performs the thresholding based on the predefined technique. 

Author(s): 

Nicolai van Niekerk, Stephan Nell 

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') 

@staticmethod 

def adaptiveThresholding(image): 

""" 

This function applies a simple adaptive thresholding to the image passed. 

Author(s): 

Stephan Nell 

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) 

@staticmethod 

def otsuThresholding(image): 

""" 

This function applies a simple Binary Inverse Otso thresholding to the image passed. 

Author(s): 

Stephan Nell 

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