# pyright: reportUnusedImport=false
# ruff: noqa: F401
# Imports
from .common import Any, NDArray, check_image, cv2, np
# Functions
[docs]
def zoom_image(image: NDArray[Any], zoom_factor: float, ignore_dtype: bool = False) -> NDArray[Any]:
""" Zoom into an image.
Args:
image (NDArray[Any]): Image to zoom
zoom_factor (float): Zoom factor (greater than 1 for zoom in, less than 1 for zoom out)
ignore_dtype (bool): Ignore the dtype check
Returns:
NDArray[Any]: Zoomed image
>>> ## Basic tests
>>> image = np.array([[1, 2, 3], [4, 5, 6], [7, 8, 9]])
>>> zoomed = zoom_image(image.astype(np.uint8), 1.5)
>>> zoomed.shape == image.shape
True
>>> img = np.eye(4, dtype=np.uint8) * 255
>>> zoomed_in = zoom_image(img, 2.0)
>>> zoomed_in.shape == img.shape # Should preserve size
True
>>> zoomed_out = zoom_image(img, 0.5)
>>> zoomed_out.shape == img.shape # Should preserve size
True
>>> rgb = np.full((4,4,3), 128, dtype=np.uint8)
>>> zoomed_rgb = zoom_image(rgb, 1.5)
>>> zoomed_rgb.shape == (4,4,3)
True
>>> ## Test invalid inputs
>>> zoom_image("not an image", 1.5)
Traceback (most recent call last):
...
AssertionError: Image must be a numpy array
>>> zoom_image(image.astype(np.uint8), "1.5")
Traceback (most recent call last):
...
AssertionError: zoom_factor must be a number, got <class 'str'>
>>> zoom_image(image.astype(np.uint8), -1)
Traceback (most recent call last):
...
AssertionError: zoom_factor must be greater than 0, got -1
"""
# Check input data
check_image(image, ignore_dtype=ignore_dtype)
assert isinstance(zoom_factor, float | int), f"zoom_factor must be a number, got {type(zoom_factor)}"
assert zoom_factor > 0, f"zoom_factor must be greater than 0, got {zoom_factor}"
# Get image dimensions
height, width = image.shape[:2]
# Calculate new dimensions
new_height, new_width = int(height * zoom_factor), int(width * zoom_factor)
# Resize image
zoomed_image: NDArray[Any] = cv2.resize(image, (new_width, new_height))
# Crop or pad to original size
if zoom_factor > 1:
# Crop
start_x: int = (new_width - width) // 2
start_y: int = (new_height - height) // 2
return zoomed_image[start_y:start_y + height, start_x:start_x + width] # pyright: ignore [reportUnknownVariableType]
else:
# Pad
pad_x: int = (width - new_width) // 2
pad_y: int = (height - new_height) // 2
# Ensure value list matches number of channels (max 4 for OpenCV)
value: list[int] = [0] * min(image.shape[-1], 4)
return cv2.copyMakeBorder(zoomed_image, pad_y, pad_y, pad_x, pad_x, cv2.BORDER_CONSTANT, value=value)
