Description
Question 1: Autoencoder [2.5 pts]
Implement autoencoder using MNIST dataset. The input size of the images will be 28×28 with single channel. You
will implement two different variations, one with fully connected layers (standard neural network), and the other
with convolutional neural network.
Your tasks:
• Implement an autoencoder using fully connected layers. The encoder will have 2 layers (with 256, and 128
neurons) and the decoder will also have two layers (with 256 and 784 neurons). Train this network using MSE
loss for 10 epochs. Compare the number of parameters in the encoder and the decoder.
Show 20 sample
reconstructed images from testing data in the report (2 image for each class) along with the original images.
• Implement a convolutional autoencoder for MNIST dataset. The encoder will have two concolutional layers,
and two max-pooling layers followed by each convolutional layers.
Use kernel size 3×3, relu activation, and
padding of 1 to preserve the shape of the input feature map. The decoder will have three convolutional layers
with kernel shape 3×3 and padding of 1 to preserve the feature map shape. The first two convolution layer will
be followed by an upsampling layer, which will double the resolution of feature maps using linear interpolation.
Train this network for 10 epochs.
Compare the number of parameters in the encoder and the decoder. Also,
compare the total parameters in this autoencoder with the autoencoder in the previous task. Show 20 sample
reconstructed images from testing data in the report (2 image for each class) along with the original images.
Also compate the reconstructed results with the previous autoencoder.
NOTE: You are free to choose any optimizer, but use the same optimizer for both the variations. Feel free to use
the code shared in the first assignment for data loader and other base classes.
What to submit:
• Code
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• A short write-up about your implementation with results (as indicated for each variation) and your observations
from each training.
Question 2: Nearest Neighbor Classification [2.5 pts]
In this question, the task is to implement nearest neighbor classifier for digit classification. You will use the digit
dataset available from sklearn library. There are around 1800 images in total with 10 digit classes, and each image
is 8×8 sized with single channel. You will have to split the dataset into training and testing, keep 500 images for
testing (you will have to choose them randomly with 50 images per class).
NOTE: We have not covered this topic in class yet, it will be discussed next week.
Sample code to load the dataset from sklearn,
from sklearn.datasets import load_digits
digits = load_digits()
Your tasks:
• Implement a nearest neighbor classifier using pixels as features. Test the method for classification accuray.
• Implement a k-nearest neighbor classifier using pixels as features. Test the method for k=3, 5, and 7 and
compute classification accuracy.
NOTE: You can use L2-norm for distance between two samples.
What to submit:
• Code
• A short write-up about your implementation with results: 1) Accuracy scores for all the variations, 2) Compare
all the variations using accuracy scores. Comment of how the accuracy changes when you increase the value
of k.
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