Processing Module

The processing module provides functions for basic image processing operations such as thresholding.

Image processing operations.

This module provides functions for basic image processing operations such as thresholding.

Functions:

threshold: Apply binary threshold to grayscale images.

cv3.processing.threshold(img: ndarray, thr=127, max=None, type=None, rel=None)

Apply threshold to a grayscale image.

Parameters:

• img (numpy.ndarray) – Input grayscale image.

• thr (int or float, optional) – Threshold value. Defaults to 127.

• max (int or float, optional) – Maximum value to use with the thresholding. If None, defaults to 255. Defaults to None.

• type (int or str, optional) – Threshold type. Can be an OpenCV threshold flag or string. Available string options: ‘binary’, ‘binary_inv’, ‘trunc’, ‘tozero’, ‘tozero_inv’. If None, defaults to opt.THRESHOLD_TYPE. Defaults to None.

• rel (bool, optional) – Whether to use relative threshold value. Defaults to None.

Returns:

Thresholded image.

Return type:

numpy.ndarray

Raises:

AssertionError – If the input image is not a grayscale image.

Note

This function applies thresholding using the specified threshold type. Pixels are processed according to the chosen thresholding method.

Relative threshold values are in the range [0, 1] where 0 is the minimum and 1 is the maximum pixel value in the image.

Example

>>> import cv3
>>> import numpy as np
>>> # Create a simple grayscale image
>>> img = np.zeros((100, 100), dtype=np.uint8)
>>> img[25:75, 25:75] = 128  # Gray square
>>> # Apply threshold with default type
>>> thresh = cv3.threshold(img, 100)
>>> # Apply threshold with custom type
>>> thresh = cv3.threshold(img, 100, type='binary_inv')
>>> # Apply threshold with relative threshold value
>>> thresh = cv3.threshold(img, 0.5, rel=True)

threshold(img[, thr, max, type, rel])

Apply threshold to a grayscale image.