Warum ist der Begrenzungsbox nicht auf das Quadrat ausgerichtet? ⇐ Python

[Anonymous]

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import numpy as np
import matplotlib.pyplot as plt
from matplotlib.patches import Rectangle

def generate_square_image(size, square_size, noise_level=0.0):
"""
Generates an image with a white square in the center.

Args:
size (int): The size of the image (size x size).
square_size (int): The size of the square.
noise_level (float): Standard deviation of Gaussian noise.

Returns:
numpy.ndarray: The image as a numpy array.
numpy.ndarray: The mask.
tuple: Bounding box (x_min, y_min, width, height).
"""

# create mask
mask = np.zeros((size, size))
start = (size - square_size) // 2
end = start + square_size
mask[start:end, start:end] = 1

# create bounding box
bbox = (start, start, square_size, square_size)

# create noisy image
img = mask.copy()
if noise_level > 0:
noise = np.random.normal(0, noise_level, img.shape)
img = np.clip(img + noise, 0, 1)

return img, mask, bbox

# Example usage:
size = 100
square_size = 40
img, mask, bbox = generate_square_image(size, square_size, noise_level=0.1)

# Plot the image
fig, ax = plt.subplots(1, 3, figsize=(15, 5))
ax[0].imshow(img, cmap='gray')
ax[0].set_title('Generated Image')
ax[1].imshow(mask, cmap='gray')
ax[1].set_title('Mask')

# Display the bounding box overlayed on the image
ax[2].imshow(img, cmap='gray')
x, y, width, height = bbox
# The key fix: in matplotlib, the Rectangle coordinates start at the bottom-left corner
# But imshow displays arrays with the origin at the top-left corner
rect = Rectangle((x, y), width, height, linewidth=2, edgecolor='r', facecolor='none')
ax[2].add_patch(rect)
ax[2].set_title('Image with Bounding Box')

# Ensure origin is set to 'upper' to match imshow defaults
for a in ax:
a.set_ylim([size, 0])  # Reverse y-axis to match array indexing

plt.tight_layout()
plt.show()

Frage: < Eins?>