Color-Based Segmentation

import cv2
import numpy as np

def segment_by_colour(image_path, lower_hsv, upper_hsv, output_path):
    """Segment and extract objects by colour range."""

    image = cv2.imread(image_path)
    hsv = cv2.cvtColor(image, cv2.COLOR_BGR2HSV)

    # Create colour mask
    mask = cv2.inRange(hsv, np.array(lower_hsv), np.array(upper_hsv))

    # Clean mask with morphological operations
    kernel = np.ones((7, 7), np.uint8)
    mask = cv2.morphologyEx(mask, cv2.MORPH_OPEN, kernel)   # Remove noise
    mask = cv2.morphologyEx(mask, cv2.MORPH_CLOSE, kernel)  # Fill gaps
    mask = cv2.dilate(mask, kernel, iterations=1)            # Slightly expand

    # Extract colour region
    segmented = cv2.bitwise_and(image, image, mask=mask)

    # Create a result with white background for the non-masked area
    background = np.ones_like(image) * 255  # White background
    inverse_mask = cv2.bitwise_not(mask)
    background_part = cv2.bitwise_and(background, background, mask=inverse_mask)
    result = cv2.add(segmented, background_part)

    cv2.imwrite(output_path, result)
    print(f"Segmented coverage: {cv2.countNonZero(mask)/mask.size*100:.1f}%")
    return result, mask

# Example: segment green plants from a garden image
segment_by_colour(
    "garden.jpg",
    lower_hsv=[35, 60, 60],
    upper_hsv=[85, 255, 255],
    output_path="plants_segmented.jpg"
)