import cv2

def to_black(image, transfer_style):
    if transfer_style == "Hayao":
         output = cv2.cvtColor(image, cv2.COLOR_BGR2GRAY)# 转换为灰度图像
         return output
    elif transfer_style == "Shinkai":
        return image
    elif transfer_style == "Kon Satoshi":
        return image
    else:
        return image