import numpy as np
import cv2
from typing import Union
def sendErrorShape(shapeC):
raise TypeError("Expect contour in form (N, 2) not {}".format(shapeC))
[docs]def make_mask_contour(img_shape: tuple, contour: Union[list, np.ndarray]) -> np.ndarray:
"""
Create a binary mask from a given contour and image shape. The mask sets pixels inside the contour to 1 (True)
and pixels outside to 0 (False).
Args:
img_shape (tuple): The shape of the image given in image coordinates, represented as (width, height).
contour (list or np.ndarray): The contour as outputted by OpenCV, with shape (N, 2).
Returns:
np.ndarray: A boolean image where the area enclosed by the contour is True and the rest is False.
Raises:
TypeError: If the provided contour is not in the form (N, 2), where N is the number of points.
Example::
# Usage example with OpenCV's contour output
img_shape = (640, 480) # Width and height of the target image
contour = np.array([[100, 200], [200, 100], [300, 400]], dtype=np.int32)
mask = make_mask_contour(img_shape, contour)
# 'mask' will contain a binary mask representing the specified contour.
"""
contour = np.array(contour, dtype=np.int32)
shapeC = np.shape(contour)
if len(shapeC) != 2:
sendErrorShape(shapeC)
if shapeC[1] != 2:
sendErrorShape(shapeC)
contour = contour.reshape((1, shapeC[0], 2))
mask = np.zeros((img_shape[1], img_shape[0]), dtype=np.uint8)
cv2.fillPoly(mask, contour, 1)
return mask