discriminator.py

from keras.models import Sequential
from keras.layers import Dense, Activation
from keras.layers import LeakyReLU
from keras.layers import MaxPooling2D, Conv2D, Flatten

def build_discriminator():
    dis_model = Sequential()
    dis_model.add(
        Conv2D(128, (5, 5),
               padding='same',
               input_shape=(64, 64, 3))
    )
    dis_model.add(LeakyReLU(alpha=0.2))
    dis_model.add(MaxPooling2D(pool_size=(2, 2)))

    dis_model.add(Conv2D(256, (3, 3)))
    dis_model.add(LeakyReLU(alpha=0.2))
    dis_model.add(MaxPooling2D(pool_size=(2, 2)))

    dis_model.add(Conv2D(512, (3, 3)))
    dis_model.add(LeakyReLU(alpha=0.2))
    dis_model.add(MaxPooling2D(pool_size=(2, 2)))

    dis_model.add(Flatten())
    dis_model.add(Dense(1024))
    dis_model.add(LeakyReLU(alpha=0.2))

    dis_model.add(Dense(1))
    dis_model.add(Activation('sigmoid'))

    return dis_model