import cv2
import numpy as np

def preprocess_image(image: np.ndarray) -> np.ndarray:
    # Simple preprocessing: enhance contrast
    lab = cv2.cvtColor(image, cv2.COLOR_BGR2LAB)
    clahe = cv2.createCLAHE(clipLimit=2.0, tileGridSize=(8, 8))
    lab[:, :, 0] = clahe.apply(lab[:, :, 0])
    return cv2.cvtColor(lab, cv2.COLOR_LAB2BGR)

def extract_features(image: np.ndarray, mask: np.ndarray) -> dict:
    # Extract color histogram
    color_histogram = cv2.calcHist([image], [0, 1, 2], mask, [8, 8, 8], [0, 256, 0, 256, 0, 256])
    color_histogram = cv2.normalize(color_histogram, color_histogram).flatten()
    return {'color': color_histogram}