import tensorflow as tf

def preprocess_image(image_path, target_size=(299, 299)):
    """
    Preprocesses a chest X-ray image for the model.
    
    Args:
        image_path: Path to the image file
        target_size: Target size for resizing
        
    Returns:
        Preprocessed image tensor ready for prediction
    """
    # Read image
    img = tf.io.read_file(image_path)
    img = tf.image.decode_image(img, channels=3)
    
    # Resize
    img = tf.image.resize(img, target_size)
    
    # Normalize to [0,1]
    img = img / 255.0
    
    # Add batch dimension
    img = tf.expand_dims(img, 0)
    
    return img