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199/199 [==============================] - 31s 157ms/step - loss: 0.2360 - val_loss: 0.3950 |
Epoch 11/15 |
199/199 [==============================] - 31s 157ms/step - loss: 0.2247 - val_loss: 0.4139 |
Epoch 12/15 |
199/199 [==============================] - 31s 157ms/step - loss: 0.2126 - val_loss: 0.3861 |
Epoch 13/15 |
199/199 [==============================] - 31s 157ms/step - loss: 0.2026 - val_loss: 0.4138 |
Epoch 14/15 |
199/199 [==============================] - 31s 156ms/step - loss: 0.1932 - val_loss: 0.4265 |
Epoch 15/15 |
199/199 [==============================] - 31s 157ms/step - loss: 0.1857 - val_loss: 0.3959 |
<tensorflow.python.keras.callbacks.History at 0x7f6e11107b70> |
Visualize predictions |
# Generate predictions for all images in the validation set |
val_gen = OxfordPets(batch_size, img_size, val_input_img_paths, val_target_img_paths) |
val_preds = model.predict(val_gen) |
def display_mask(i): |
\"\"\"Quick utility to display a model's prediction.\"\"\" |
mask = np.argmax(val_preds[i], axis=-1) |
mask = np.expand_dims(mask, axis=-1) |
img = PIL.ImageOps.autocontrast(keras.preprocessing.image.array_to_img(mask)) |
display(img) |
# Display results for validation image #10 |
i = 10 |
# Display input image |
display(Image(filename=val_input_img_paths[i])) |
# Display ground-truth target mask |
img = PIL.ImageOps.autocontrast(load_img(val_target_img_paths[i])) |
display(img) |
# Display mask predicted by our model |
display_mask(i) # Note that the model only sees inputs at 150x150. |
jpeg |
png |
png |
Similarity learning using a siamese network trained with a contrastive loss. |
Introduction |
Siamese Networks are neural networks which share weights between two or more sister networks, each producing embedding vectors of its respective inputs. |
In supervised similarity learning, the networks are then trained to maximize the contrast (distance) between embeddings of inputs of different classes, while minimizing the distance between embeddings of similar classes, resulting in embedding spaces that reflect the class segmentation of the training inputs. |
Setup |
import random |
import numpy as np |
import tensorflow as tf |
from tensorflow import keras |
from tensorflow.keras import layers |
import matplotlib.pyplot as plt |
Hyperparameters |
epochs = 10 |
batch_size = 16 |
margin = 1 # Margin for constrastive loss. |
Load the MNIST dataset |
(x_train_val, y_train_val), (x_test, y_test) = keras.datasets.mnist.load_data() |
# Change the data type to a floating point format |
x_train_val = x_train_val.astype(\"float32\") |
x_test = x_test.astype(\"float32\") |
Define training and validation sets |
# Keep 50% of train_val in validation set |
x_train, x_val = x_train_val[:30000], x_train_val[30000:] |
y_train, y_val = y_train_val[:30000], y_train_val[30000:] |
del x_train_val, y_train_val |
Create pairs of images |
We will train the model to differentiate between digits of different classes. For example, digit 0 needs to be differentiated from the rest of the digits (1 through 9), digit 1 - from 0 and 2 through 9, and so on. To carry this out, we will select N random images from class A (for example, for digit 0) and pair them wi... |
def make_pairs(x, y): |
\"\"\"Creates a tuple containing image pairs with corresponding label. |
Arguments: |
x: List containing images, each index in this list corresponds to one image. |
y: List containing labels, each label with datatype of `int`. |
Returns: |
Tuple containing two numpy arrays as (pairs_of_samples, labels), |
where pairs_of_samples' shape is (2len(x), 2,n_features_dims) and |
labels are a binary array of shape (2len(x)). |
\"\"\" |
num_classes = max(y) + 1 |
digit_indices = [np.where(y == i)[0] for i in range(num_classes)] |
pairs = [] |
labels = [] |
for idx1 in range(len(x)): |
# add a matching example |
x1 = x[idx1] |
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