I have images where there will be outer boundaries like rectangles or even hand shapes and within their borders will be some other shapes including complex ones. I need to separate the outer shape (rectangle, etc.) and the inner content. I would like them to maintain their thickness, etc. For example this is how my input images look, in simple cases: All my images will be black and white like that. I would like the above image to be separated like this: I have tried many things, but nothing seems to work. For example this: def remove_outer_boundary(image_path, border_thickness=20, inpaint_radius=3): """ Removes only the outer frame lines of thickness `border_thickness`, preserving all interior content. Args: image_path (str): Path to the input image. border_thickness (int): Approximate pixel thickness of the outer border. inpaint_radius (int): Radius for the inpainting algorithm. Returns: result (np.ndarray): Image with only the border removed. """ # 1. Load and gray img = cv2.imread(image_path) if img is None: raise FileNotFoundError(f"Cannot read: {image_path}") gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY) # 2. Binary inverse threshold to pick up lines thresh = cv2.adaptiveThreshold( gray, 255, cv2.ADAPTIVE_THRESH_GAUSSIAN_C, cv2.THRESH_BINARY_INV, blockSize=51, C=10) # 3. Find largest external contour contours, _ = cv2.findContours( thresh, cv2.RETR_EXTERNAL, cv2.CHAIN_APPROX_SIMPLE) if not contours: return img.copy() outer = max(contours, key=cv2.contourArea) # 4. Fill that contour to get its full region filled = np.zeros_like(gray) cv2.drawContours(filled, [outer], -1, 255, thickness=cv2.FILLED) # 5. Morphological gradient to isolate just the border k = border_thickness // 2 * 2 + 1 # make it odd kernel = cv2.getStructuringElement(cv2.MORPH_RECT, (k, k)) border_mask = cv2.morphologyEx(filled, cv2.MORPH_GRADIENT, kernel) # 6. Inpaint only the border_mask result = cv2.inpaint(img, border_mask, inpaint_radius, cv2.INPAINT_TELEA) return result I was trying to see if removing the outer rectangle might work. But it needs thickness etc. stuff. And doesn't work in some other cases such as hand shapes (outlines), leaves some smudges, etc. Continue reading...
