Modified from Keras examples:
https://github.com/fchollet/keras/blob/master/examples/mnist_acgan.py
Original repo: https://github.com/lukedeo/keras-acgan
Here, we use the tensorflow backend. The learning rate is decreased.
In [2]:
from PIL import Image
from keras.datasets import mnist
from keras.layers import Input, Dense, Reshape, Flatten, Embedding, Dropout
from keras.layers import Multiply, LeakyReLU, UpSampling2D, Conv2D
from keras.models import Sequential, Model
from keras.optimizers import Adam
import numpy as np
np.random.seed(1337)
In [3]:
def build_generator(latent_size):
# we will map a pair of (z, L), where z is a latent vector and L is a
# label drawn from P_c, to image space (..., 28, 28, 1)
cnn = Sequential()
cnn.add(Dense(1024, input_dim=latent_size, activation='relu'))
cnn.add(Dense(128 * 7 * 7, activation='relu'))
cnn.add(Reshape((7, 7, 128)))
# upsample to (..., 14, 14)
cnn.add(UpSampling2D(size=(2, 2)))
cnn.add(Conv2D(256, 5, padding='same', activation='relu',
kernel_initializer='glorot_normal'))
# upsample to (..., 28, 28)
cnn.add(UpSampling2D(size=(2, 2)))
cnn.add(Conv2D(128, 5, padding='same', activation='relu',
kernel_initializer='glorot_normal'))
# take a channel axis reduction
cnn.add(Conv2D(1, 2, padding='same', activation='tanh',
kernel_initializer='glorot_normal'))
# this is the z space commonly refered to in GAN papers
latent = Input(shape=(latent_size,))
# this will be our label
image_class = Input(shape=(1,), dtype='int32')
# 10 classes in MNIST
emb = Embedding(10, latent_size, embeddings_initializer='glorot_normal')(image_class)
cls = Flatten()(emb)
# hadamard product between z-space and a class conditional embedding
h = Multiply()([latent, cls])
fake_image = cnn(h)
return Model([latent, image_class], fake_image)
def build_discriminator():
# build a relatively standard conv net, with LeakyReLUs as suggested in
# the reference paper
cnn = Sequential()
cnn.add(Conv2D(32, 3, padding='same', strides=2, input_shape=(28, 28, 1)))
cnn.add(LeakyReLU())
cnn.add(Dropout(0.3))
cnn.add(Conv2D(64, 3, padding='same', strides=1))
cnn.add(LeakyReLU())
cnn.add(Dropout(0.3))
cnn.add(Conv2D(128, 3, padding='same', strides=2))
cnn.add(LeakyReLU())
cnn.add(Dropout(0.3))
cnn.add(Conv2D(256, 3, padding='same', strides=1))
cnn.add(LeakyReLU())
cnn.add(Dropout(0.3))
cnn.add(Flatten())
image = Input(shape=(28, 28, 1))
features = cnn(image)
# first output (name=generation) is whether or not the discriminator
# thinks the image that is being shown is fake, and the second output
# (name=auxiliary) is the class that the discriminator thinks the image
# belongs to.
fake = Dense(1, activation='sigmoid', name='generation')(features)
aux = Dense(10, activation='softmax', name='auxiliary')(features)
return Model(image, [fake, aux])
In [4]:
# batch and latent size taken from the paper
epochs = 50
batch_size = 100
latent_size = 100
# Adam parameters suggested in https://arxiv.org/abs/1511.06434
# decreased learning rate from repo settings
adam_lr = 0.00005
adam_beta_1 = 0.5
# build the discriminator
discriminator = build_discriminator()
discriminator.compile(
optimizer=Adam(lr=adam_lr, beta_1=adam_beta_1),
loss=['binary_crossentropy', 'sparse_categorical_crossentropy']
)
# build the generator
generator = build_generator(latent_size)
generator.compile(
optimizer=Adam(lr=adam_lr, beta_1=adam_beta_1),
loss='binary_crossentropy'
)
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generator.summary()
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discriminator.summary()
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latent = Input(shape=(latent_size, ))
image_class = Input(shape=(1,), dtype='int32')
# get a fake image
fake = generator([latent, image_class])
# we only want to be able to train generation for the combined model
discriminator.trainable = False
fake, aux = discriminator(fake)
combined = Model([latent, image_class], [fake, aux])
combined.compile(
optimizer=Adam(lr=adam_lr, beta_1=adam_beta_1),
loss=['binary_crossentropy', 'sparse_categorical_crossentropy']
)
# get our mnist data, and force it to be of shape (..., 28, 28, 1) with
# range [-1, 1]
(X_train, y_train), (X_test, y_test) = mnist.load_data()
X_train = (X_train.astype(np.float32) - 127.5) / 127.5
X_train = np.expand_dims(X_train, axis=3)
X_test = (X_test.astype(np.float32) - 127.5) / 127.5
X_test = np.expand_dims(X_test, axis=3)
num_train, num_test = X_train.shape[0], X_test.shape[0]
In [8]:
print('Epoch\tL_s(G)\tL_s(G)\tL_s(D)\tL_s(D)\tL_c(G)\tL_c(G)\tL_c(D)\tL_c(D)')
for epoch in range(epochs):
print(epoch + 1, end='\t', flush=True)
num_batches = int(X_train.shape[0] / batch_size)
epoch_gen_loss = []
epoch_disc_loss = []
for index in range(num_batches):
# generate a new batch of noise
noise = np.random.uniform(-1, 1, (batch_size, latent_size))
# get a batch of real images
image_batch = X_train[index * batch_size:(index + 1) * batch_size]
label_batch = y_train[index * batch_size:(index + 1) * batch_size]
# sample some labels from p_c
sampled_labels = np.random.randint(0, 10, batch_size)
# generate a batch of fake images, using the generated labels as a
# conditioner. We reshape the sampled labels to be
# (batch_size, 1) so that we can feed them into the embedding
# layer as a length one sequence
generated_images = generator.predict(
[noise, sampled_labels.reshape((-1, 1))], verbose=0)
X = np.concatenate((image_batch, generated_images))
y = np.array([1] * batch_size + [0] * batch_size)
aux_y = np.concatenate((label_batch, sampled_labels), axis=0)
# see if the discriminator can figure itself out...
epoch_disc_loss.append(discriminator.train_on_batch(X, [y, aux_y]))
# make new noise. we generate 2 * batch size here such that we have
# the generator optimize over an identical number of images as the
# discriminator
noise = np.random.uniform(-1, 1, (2 * batch_size, latent_size))
sampled_labels = np.random.randint(0, 10, 2 * batch_size)
# we want to train the generator to trick the discriminator
# For the generator, we want all the {fake, not-fake} labels to say
# not-fake
trick = np.ones(2 * batch_size)
epoch_gen_loss.append(
combined.train_on_batch(
[noise, sampled_labels.reshape((-1, 1))],
[trick, sampled_labels]
)
)
# evaluate the testing loss here
# generate a new batch of noise
noise = np.random.uniform(-1, 1, (num_test, latent_size))
# sample some labels from p_c and generate images from them
sampled_labels = np.random.randint(0, 10, num_test)
generated_images = generator.predict(
[noise, sampled_labels.reshape((-1, 1))], verbose=0)
X = np.concatenate((X_test, generated_images))
y = np.array([1] * num_test + [0] * num_test)
aux_y = np.concatenate((y_test, sampled_labels), axis=0)
# see if the discriminator can figure itself out...
discriminator_test_loss = discriminator.evaluate(X, [y, aux_y], verbose=0)
discriminator_train_loss = np.mean(np.array(epoch_disc_loss), axis=0)
# make new noise
noise = np.random.uniform(-1, 1, (2 * num_test, latent_size))
sampled_labels = np.random.randint(0, 10, 2 * num_test)
trick = np.ones(2 * num_test)
generator_test_loss = combined.evaluate(
[noise, sampled_labels.reshape((-1, 1))],
[trick, sampled_labels],
verbose=0
)
generator_train_loss = np.mean(np.array(epoch_gen_loss), axis=0)
print('{:.4f}\t{:.4f}\t{:.4f}\t{:.4f}\t{:.4f}\t{:.4f}\t{:.4f}\t{:.4f}'.format(
# generation loss
generator_train_loss[1], generator_test_loss[1],
discriminator_train_loss[1], discriminator_test_loss[1],
# auxillary loss
generator_train_loss[2], generator_test_loss[2],
discriminator_train_loss[2], discriminator_test_loss[2],
))
# save weights every epoch
generator.save_weights('mnist_acgan/mnist_acgan_g_weights.hdf5', True)
discriminator.save_weights('mnist_acgan/mnist_acgan_d_weights.hdf5', True)
# generate some digits to display
noise = np.random.uniform(-1, 1, (100, latent_size))
sampled_labels = np.array([[i] * 10 for i in range(10)]).reshape(-1, 1)
# get a batch to display
generated_images = generator.predict([noise, sampled_labels], verbose=0)
# arrange them into a grid
img = (np.concatenate([r.reshape(-1, 28)
for r in np.split(generated_images, 10)
], axis=-1) * 127.5 + 127.5).astype(np.uint8)
Image.fromarray(img).save('mnist_acgan/mnist_acgan_generated_{0:03d}.png'.format(epoch))
print('done.')
In [9]:
with open('mnist_acgan.json', 'w') as f:
f.write(generator.to_json())
In [34]:
!cp mnist_acgan/mnist_acgan_g_weights.hdf5 ./mnist_acgan.hdf5
epoch 50:
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import matplotlib.pyplot as plt
%matplotlib inline
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def make_digit(digit=None):
noise = np.random.uniform(-1, 1, (1, latent_size))
sampled_label = np.array([
digit if digit is not None else np.random.randint(0, 10, 1)
]).reshape(-1, 1)
generated_image = generator.predict(
[noise, sampled_label], verbose=0)
return np.squeeze((generated_image * 127.5 + 127.5).astype(np.uint8))
In [33]:
plt.imshow(make_digit(digit=6), cmap='gray_r', interpolation='nearest')
plt.axis('off')
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