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Training of Convolutional Neural Network (CNN) in TensorFlow

  • Difficulty Level : Expert
  • Last Updated : 10 Jan, 2022

In this article, we are going to implement and train a convolutional neural network CNN using TensorFlow a massive machine learning library.

Now in this article, we are going to work on a dataset called ‘rock_paper_sissors’ where we need to simply classify the hand signs as rock paper or scissors. 

Stepwise Implementation

Step 1: Importing the libraries

We are going to start with importing some important libraries. They are TensorFlow, NumPy, Matplotlib, and finally from TensorFlow, we need TensorFlow datasets and Keras

Python




pip install -q tensorflow tensorflow-datasets
 
# Importing the packages
import matplotlib.pyplot as plt
import numpy as np
 
import tensorflow as tf
import tensorflow_datasets as tfds
 
from tensorflow import keras

Step 2: Loading the dataset

Before choosing the dataset feel free to explore all the datasets available in TensorFlow

Python




tfds.list_builders()

Output:

['abstract_reasoning',
 'accentdb',
 'aeslc',
 'aflw2k3d',
 'ag_news_subset',
 'ai2_arc',
 'ai2_arc_with_ir',
 'amazon_us_reviews',
 'anli',
 'arc',
 'bair_robot_pushing_small',
 'bccd',
 'beans',
 'big_patent',
 ....
 ..
 .

Before loading the dataset we shall see some info about our dataset so that it will be easy for us to work with the data and to gather some very important information.

Python




# Getting info about the dataset
Dataset = tfds.builder('rock_paper_scissors')
info = Dataset.info
 
print(info)

Output: 

tfds.core.DatasetInfo(
    name='rock_paper_scissors',
    full_name='rock_paper_scissors/3.0.0',
    description="""
    Images of hands playing rock, paper, scissor game.
    """,
    homepage='http://laurencemoroney.com/rock-paper-scissors-dataset',
    data_path='C:\\Users\\ksaty\\tensorflow_datasets\\rock_paper_scissors\\3.0.0',
    download_size=Unknown size,
    dataset_size=Unknown size,
    features=FeaturesDict({
        'image': Image(shape=(300, 300, 3), dtype=tf.uint8),
        'label': ClassLabel(shape=(), dtype=tf.int64, num_classes=3),
    }),
    supervised_keys=('image', 'label'),
    disable_shuffling=False,
    splits={
    },
    citation="""@ONLINE {rps,
    author = "Laurence Moroney",
    title = "Rock, Paper, Scissors Dataset",
    month = "feb",
    year = "2019",
    url = "http://laurencemoroney.com/rock-paper-scissors-dataset"
    }""",
)

Finally loading the dataset,

Python




# Loading the dataset
ds_train = tfds.load(name="rock_paper_scissors", split="train")
ds_test = tfds.load(name="rock_paper_scissors", split="test")

Output:

Downloading and preparing dataset Unknown size (download: Unknown size, generated: Unknown size, total: Unknown size) to C:\Users\ksaty\tensorflow_datasets\rock_paper_scissors\3.0.0…

Dl Completed…: 100%

2/2 [00:50<00:00, 25.01s/ url]

Dl Size…: 100%

219/219 [00:50<00:00, 4.38 MiB/s]

Dataset rock_paper_scissors downloaded and prepared to C:\Users\ksaty\tensorflow_datasets\rock_paper_scissors\3.0.0. Subsequent calls will reuse this data.

Some of the examples 

Step 3: Analyzing and preprocessing the images

First, to keep it clean we are going to iterate over the data and store it as a NumPy array and cancel the dimensions of the image and store it as train_images, and test images with labels.

Python




# Iterating over the images and storing
# it in train and test datas
train_images = np.array([image['image'].numpy()[:, :, 0]
                         for image in ds_train])
train_labels = np.array([image['label']
                         .numpy() for image in ds_train])
 
test_images = np.array([image['image'].numpy()[:, :, 0] for image in ds_test])
test_labels = np.array([image['label'].numpy() for image in ds_test])

and then, now we are going to reshape the images and then convert the datatype to float32 from uint8, and then we are going to get all the values down to 0 to 1 for making it easier for the model to learn from it.

Python




# Reshaping the images
train_images = train_images.reshape(2520, 300, 300, 1)
test_images = test_images.reshape(372, 300, 300, 1)
 
# Changing the datatype
train_images = train_images.astype('float32')
test_images = test_images.astype('float32')
 
# getting the values down to 0 and 1
train_images /= 255
test_images /= 255

Step 4: A basic convolutional neural network

Now we are going to create a basic CNN with only 2 convolutional layers with a relu activation function and 64 and 32 kernels and a kernel size of 3 and flatten the image to a 1D array and the convolutional layers are directly connected to the output layer.

And for compiling we use Adam optimizer and for the loss we are using SparseCategoricalCrossentropy() and for metrics, we use accuracy and going to fit the data.

Python




# A convolutional neural network
 
# Defining the model
model = keras.Sequential([
    keras.layers.Conv2D(64, 3, activation='relu',
                        input_shape=(300, 300, 1)),
    keras.layers.Conv2D(32, 3, activation='relu'),
    keras.layers.Flatten(),
    keras.layers.Dense(3, activation='softmax')
])
 
# Compiling the model
model.compile(optimizer='adam',
              loss=keras.losses.SparseCategoricalCrossentropy(),
              metrics=['accuracy'])
 
# Fitting the model with data
model.fit(train_images, train_labels, epochs=5,
          batch_size=32)

Output:

And to evaluate the model

Python




model.evaluate(test_images, test_labels)

As you can see there is a very low accuracy in unseen data this is called model overfitting which means the model is overfitted by the training data so it cannot handle the unseen data to solve this we can modify the model a little bit.

Better convolutional neural network

We can improve this model by adding:

  • Dropout nodes
  • Pooling
  • Fully connected dense layers

Python




# A better convolutional neural network
 
# Model defining
model = keras.Sequential([
    keras.layers.AveragePooling2D(6, 3,
                                  input_shape=(300, 300, 1)),
    keras.layers.Conv2D(64, 3, activation='relu'),
    keras.layers.Conv2D(32, 3, activation='relu'),
    keras.layers.MaxPool2D(2, 2),
    keras.layers.Dropout(0.5),
    keras.layers.Flatten(),
    keras.layers.Dense(128, activation='relu'),
    keras.layers.Dense(3, activation='softmax')
])
 
# Compiling a model
model.compile(optimizer='adam',
              loss=keras.losses.SparseCategoricalCrossentropy(),
              metrics=['accuracy'])
 
# Fitting the model
model.fit(train_images, train_labels, epochs=5,
          batch_size=32)

Now if we evaluate our model, As you can see the model has improved a lot.

These are the steps to train a convolutional neural network.

Note: You can still make some tweaks and turns to the model to increase the accuracy. IT is a continuous learning process.


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