import numpy as np
from keras.models import *
from keras.layers import *
from keras.applications.vgg16 import VGG16
from keras.preprocessing.image import ImageDataGenerator
from keras.optimizers import *
from keras.callbacks import ModelCheckpoint
import cv2

def train_generator(batch_size=32):
    data_gen_args = dict(featurewise_center=True,
                         rotation_range=90.,
                         width_shift_range=0.1,
                         height_shift_range=0.1,
                         fill_mode="constant",
                         cval=255,
                         horizontal_flip=True,
                         vertical_flip=True,
                         zoom_range=0.2)
    image_datagen = ImageDataGenerator(**data_gen_args)
    mask_datagen = ImageDataGenerator(**data_gen_args)

    seed = 1
    image_generator = image_datagen.flow_fr