I have an image which has a lot of rectangular smaller images on it. how to extract and save them in python?

Question

I have a group of images. Each image is a collage of multiple images.

I want to extract all the smaller images from the collage. I have tried multiple edge detection algorithms. Please suggest an alternative to my following approach.

def detect_objects(frame):
    # Convert the frame to grayscale
    gray_image = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)

    # Apply Canny edge detection
    edges = cv2.Canny(gray_image, 5, 150)

    # Convert edges to binary image using a threshold
    _, binary_edges = cv2.threshold(edges, 50, 255, cv2.THRESH_BINARY)

    # Find contours in the binary image
    contours, _ = cv2.findContours(
        binary_edges.astype(np.uint8), cv2.RETR_EXTERNAL, cv2.CHAIN_APPROX_SIMPLE
    )

    # Iterate through each contour
    for i, contour in enumerate(contours):
        # Approximate the contour to a polygon
        epsilon = 0.02 * cv2.arcLength(contour, True)
        approx = cv2.approxPolyDP(contour, epsilon, True)

        # Check if the polygon has 4 sides
        if len(approx) == 4 and cv2.contourArea(contour) > 1500:
            # Draw the contour on the frame
            cv2.drawContours(frame, [contour], -1, (0, 255, 0), 3)

            # Calculate the area of the contour
            area = cv2.contourArea(contour)
            print(f"Area of contour {i+1}: {area}")

    # Return the frame with contours
    return frame

How to make this code better? Is there a better approach to this?