我用2403张1280x720 px的图像训练CNN。这是我正在运行的代码：

from tensorflow.keras.preprocessing.image import ImageDataGenerator
import tensorflow as tf
from tensorflow import keras
from tensorflow.keras.layers import Conv2D,MaxPooling2D,Activation,Dense,Flatten,Dropout
model = keras.Sequential()
model.add(Conv2D(32, (3, 3), input_shape=(1280,720,3)))
model.add(Activation('relu'))
model.add(MaxPooling2D(pool_size=(2, 2)))
model.add(Conv2D(32, (3, 3)))
model.add(Activation('relu'))
model.add(MaxPooling2D(pool_size=(2, 2)))
model.add(Conv2D(64, (3, 3)))
model.add(Activation('relu'))
model.add(MaxPooling2D(pool_size=(2, 2)))
model.add(Flatten())
model.add(Dense(64))
model.add(Activation('relu'))
model.add(Dropout(0.5))
model.add(Dense(3))
model.add(Activation('softmax'))
model.compile(loss='categorical_crossentropy',
              optimizer='rmsprop',
              metrics=['accuracy'])
train_datagen = ImageDataGenerator(
    rescale=1. / 255,
    shear_range=0.2,
    zoom_range=0.2,
    horizontal_flip=True)
# this is the augmentation configuration we will use for testing:
# only rescaling
test_datagen = ImageDataGenerator(rescale=1. / 255)
train_generator = train_datagen.flow_from_directory(
    '/gdrive/MyDrive/shot/training',
    target_size=(1280, 720),
    batch_size=640,
    class_mode='categorical')
history = model.fit(
    train_generator,
    steps_per_epoch= 2403//640,
    epochs= 15,
)

会话在第一个epoch之前崩溃。有什么方法可以减少RAM的使用吗？我还有其他选择吗？