[Python] How to correctly plot a bounding box on a 512x512 image using coordinates in Python?

I am trying to plot a bounding box on a 512x512 image, but when I plot it, the box is not around the expected area of interest. I have extracted the top, left, bottom, and right coordinates from an XML file, and I am using these values to define the bounding box.

Here are the coordinates I have for the bounding box:

• 
  Top: 459
  
  Left: 376
  
  Right: 388
  
  Bottom: 462
  

The following points define the bounding box:

• 
  Top left: (376, 459)
  
  Top right: (388, 459)
  
  Bottom left: (376, 462)
  
  Bottom right: (388, 462)
  

I am using matplotlib to display the image and plot the bounding box on it. However, plotting the bounding box does not seem to align with the area of interest.

Here is the code I am using:

import matplotlib.pyplot as plt

# Coordinates for the bounding box
top = 459
left = 376
right = 388
bottom = 462

# Define bounding box corners
top_left = (left, top)
top_right = (right, top)
bottom_left = (left, bottom)
bottom_right = (right, bottom)

# Create the plot
fig, ax = plt.subplots()

# Set the title to the image name
ax.set_title('Image with Bounding Box')

# Display the image (assuming 'image' is your loaded 512x512 image)
ax.imshow(image, cmap='gray')

# Plot the bounding box by connecting the points
ax.plot(
[top_left[0], top_right[0], bottom_right[0], bottom_left[0], top_left[0]], # x-coordinates
[top_left[1], top_right[1], bottom_right[1], bottom_left[1], top_left[1]], # y-coordinates
markersize=5
)

# Set the limits based on image size
ax.set_xlim(0, image.shape[1]) # Set x-axis limits to the image width
ax.set_ylim(image.shape[0], 0) # Invert y-axis to match the image coordinate system

# Show the plot
plt.show()


The resulting plot is Original Image

Plot of Points on Image

Problem: The bounding box does not align with the expected area of interest. I am plotting the coordinates correctly, but the box seems to be misplaced.

What I’ve tried:

I checked the coordinates and made sure the bounding box points were correct.

I inverted the y-axis using ax.set_ylim(image.shape[0], 0) to match the image coordinate system.

Questions

What could be causing the bounding box to be misaligned?

Are there any adjustments I need to make to the plotting code for the box to align properly with the image

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