text stringlengths 0 4.99k |
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plt.title(\"Original\") |
plt.show() |
2021-11-24 01:11:00.182447: I tensorflow/stream_executor/cuda/cuda_blas.cc:1774] TensorFloat-32 will be used for the matrix multiplication. This will only be logged once. |
png |
MLP |
This serves as the fully connected feed forward network of the transformer architecture. |
def mlp(x, dropout_rate, hidden_units): |
for units in hidden_units: |
x = layers.Dense(units, activation=tf.nn.gelu)(x) |
x = layers.Dropout(dropout_rate)(x) |
return x |
MAE encoder |
The MAE encoder is ViT. The only point to note here is that the encoder outputs a layer normalized output. |
def create_encoder(num_heads=ENC_NUM_HEADS, num_layers=ENC_LAYERS): |
inputs = layers.Input((None, ENC_PROJECTION_DIM)) |
x = inputs |
for _ in range(num_layers): |
# Layer normalization 1. |
x1 = layers.LayerNormalization(epsilon=LAYER_NORM_EPS)(x) |
# Create a multi-head attention layer. |
attention_output = layers.MultiHeadAttention( |
num_heads=num_heads, key_dim=ENC_PROJECTION_DIM, dropout=0.1 |
)(x1, x1) |
# Skip connection 1. |
x2 = layers.Add()([attention_output, x]) |
# Layer normalization 2. |
x3 = layers.LayerNormalization(epsilon=LAYER_NORM_EPS)(x2) |
# MLP. |
x3 = mlp(x3, hidden_units=ENC_TRANSFORMER_UNITS, dropout_rate=0.1) |
# Skip connection 2. |
x = layers.Add()([x3, x2]) |
outputs = layers.LayerNormalization(epsilon=LAYER_NORM_EPS)(x) |
return keras.Model(inputs, outputs, name=\"mae_encoder\") |
MAE decoder |
The authors point out that they use an asymmetric autoencoder model. They use a lightweight decoder that takes \"<10% computation per token vs. the encoder\". We are not specific with the \"<10% computation\" in our implementation but have used a smaller decoder (both in terms of depth and projection dimensions). |
def create_decoder( |
num_layers=DEC_LAYERS, num_heads=DEC_NUM_HEADS, image_size=IMAGE_SIZE |
): |
inputs = layers.Input((NUM_PATCHES, ENC_PROJECTION_DIM)) |
x = layers.Dense(DEC_PROJECTION_DIM)(inputs) |
for _ in range(num_layers): |
# Layer normalization 1. |
x1 = layers.LayerNormalization(epsilon=LAYER_NORM_EPS)(x) |
# Create a multi-head attention layer. |
attention_output = layers.MultiHeadAttention( |
num_heads=num_heads, key_dim=DEC_PROJECTION_DIM, dropout=0.1 |
)(x1, x1) |
# Skip connection 1. |
x2 = layers.Add()([attention_output, x]) |
# Layer normalization 2. |
x3 = layers.LayerNormalization(epsilon=LAYER_NORM_EPS)(x2) |
# MLP. |
x3 = mlp(x3, hidden_units=DEC_TRANSFORMER_UNITS, dropout_rate=0.1) |
# Skip connection 2. |
x = layers.Add()([x3, x2]) |
x = layers.LayerNormalization(epsilon=LAYER_NORM_EPS)(x) |
x = layers.Flatten()(x) |
pre_final = layers.Dense(units=image_size * image_size * 3, activation=\"sigmoid\")(x) |
outputs = layers.Reshape((image_size, image_size, 3))(pre_final) |
return keras.Model(inputs, outputs, name=\"mae_decoder\") |
MAE trainer |
This is the trainer module. We wrap the encoder and decoder inside of a tf.keras.Model subclass. This allows us to customize what happens in the model.fit() loop. |
class MaskedAutoencoder(keras.Model): |
def __init__( |
self, |
train_augmentation_model, |
test_augmentation_model, |
patch_layer, |
patch_encoder, |
encoder, |
decoder, |
**kwargs, |
): |
super().__init__(**kwargs) |
self.train_augmentation_model = train_augmentation_model |
self.test_augmentation_model = test_augmentation_model |
self.patch_layer = patch_layer |
self.patch_encoder = patch_encoder |
self.encoder = encoder |
self.decoder = decoder |
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