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| import cv2 | |
| import khandy | |
| import numpy as np | |
| def get_2d_rotation_matrix(angle, cx=0, cy=0, scale=1, | |
| degrees=True, dtype=np.float32): | |
| """ | |
| References: | |
| `cv2.getRotationMatrix2D` in OpenCV | |
| """ | |
| if degrees: | |
| angle = np.deg2rad(angle) | |
| c = scale * np.cos(angle) | |
| s = scale * np.sin(angle) | |
| tx = cx - cx * c + cy * s | |
| ty = cy - cx * s - cy * c | |
| return np.array([[ c, -s, tx], | |
| [ s, c, ty], | |
| [ 0, 0, 1]], dtype=dtype) | |
| def rotate_image(image, angle, scale=1.0, center=None, | |
| degrees=True, border_value=0, auto_bound=False): | |
| """Rotate an image. | |
| Args: | |
| image : ndarray | |
| Image to be rotated. | |
| angle : float | |
| Rotation angle in degrees, positive values mean clockwise rotation. | |
| center : tuple | |
| Center of the rotation in the source image, by default | |
| it is the center of the image. | |
| scale : float | |
| Isotropic scale factor. | |
| degrees : bool | |
| border_value : int | |
| Border value. | |
| auto_bound : bool | |
| Whether to adjust the image size to cover the whole rotated image. | |
| Returns: | |
| ndarray: The rotated image. | |
| References: | |
| mmcv.imrotate | |
| """ | |
| assert khandy.is_numpy_image(image) | |
| image_height, image_width = image.shape[:2] | |
| if auto_bound: | |
| center = None | |
| if center is None: | |
| center = ((image_width - 1) * 0.5, (image_height - 1) * 0.5) | |
| assert isinstance(center, tuple) | |
| rotation_matrix = get_2d_rotation_matrix(angle, center[0], center[1], scale, degrees) | |
| if auto_bound: | |
| scale_cos = np.abs(rotation_matrix[0, 0]) | |
| scale_sin = np.abs(rotation_matrix[0, 1]) | |
| new_width = image_width * scale_cos + image_height * scale_sin | |
| new_height = image_width * scale_sin + image_height * scale_cos | |
| rotation_matrix[0, 2] += (new_width - image_width) * 0.5 | |
| rotation_matrix[1, 2] += (new_height - image_height) * 0.5 | |
| image_width = int(np.round(new_width)) | |
| image_height = int(np.round(new_height)) | |
| rotated = cv2.warpAffine(image, rotation_matrix[:2,:], (image_width, image_height), | |
| borderValue=border_value) | |
| return rotated | |