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Shiva Charan
Shiva Charan

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GAN - RNN - CNN - Explained

1️⃣ Generative Adversarial Network (GAN)

πŸ‘‰ What it is (simple words)

A GAN is a system of two neural networks competing against each other to generate fake data that looks real.

Think of it like:

  • Generator = a counterfeiter
  • Discriminator = a police officer

They train together until the counterfeiter becomes extremely good.


πŸ—οΈ Internal Structure

GAN has two networks:

  1. Generator
  • Takes random noise
  • Produces fake images, text, audio, etc.
  1. Discriminator
  • Takes real + fake data
  • Decides: real or fake?

They play a zero-sum game.


πŸ” Training Logic

  1. Generator creates fake data
  2. Discriminator checks it
  3. Discriminator gives feedback
  4. Generator improves
  5. Loop until fake looks real

βœ… Where GANs are used

  • Image generation (faces, art)
  • Image enhancement (super-resolution)
  • Deepfakes
  • Data augmentation
  • Style transfer

⚠️ Weaknesses

  • Hard to train
  • Can collapse (mode collapse)
  • No clear accuracy metric

2️⃣ Recurrent Neural Network (RNN)

πŸ‘‰ What it is (simple words)

An RNN is designed to remember past information.

It processes sequences step by step and carries memory forward.

Think:

  • Sentence reading
  • Time-series prediction
  • Speech recognition

πŸ—οΈ Internal Structure

  • Input at time t
  • Hidden state (memory)
  • Output at time t
  • Hidden state passes to time t+1

Same network reused at every step.


πŸ” How it works

Example: Sentence

I β†’ love β†’ AWS
Enter fullscreen mode Exit fullscreen mode
  • When reading "AWS", the model still remembers "I love"

βœ… Where RNNs are used

  • Language translation
  • Chatbots (older ones)
  • Speech recognition
  • Stock price prediction
  • Log analysis

⚠️ Weaknesses

  • Struggles with long sequences
  • Vanishing gradient problem
  • Slower training

(Reason why LSTM and GRU were invented)


3️⃣ Convolutional Neural Network (CNN)

πŸ‘‰ What it is (simple words)

A CNN is specialized for images.

It learns by detecting patterns like edges, shapes, textures, then combines them into objects.


πŸ—οΈ Internal Structure

  1. Convolution layers
  • Apply filters
  • Detect features
  1. Pooling layers
  • Reduce size
  • Keep important info
  1. Fully connected layers
  • Final decision

πŸ” How it works

Image β†’

  • Detect edges β†’
  • Detect shapes β†’
  • Detect objects β†’
  • Classification

βœ… Where CNNs are used

  • Image classification
  • Face recognition
  • Object detection
  • Medical imaging
  • Video analysis

⚠️ Weaknesses

  • Needs lots of data
  • Computationally heavy
  • Not good for sequences

πŸ”₯ Side-by-Side Comparison (IMPORTANT)

πŸ†š GAN vs RNN vs CNN

Feature GAN RNN CNN
Primary Purpose Generate new data Process sequences Process images
Key Idea Competition (Generator vs Discriminator) Memory over time Spatial feature extraction
Input Type Random noise + real data Sequential data Grid-like data (images)
Output New synthetic data Prediction per step or sequence Classification / detection
Memory ❌ No βœ… Yes ❌ No
Training Style Adversarial Sequential backprop Feedforward
Hard to Train βœ… Very ⚠️ Medium ❌ Easier
Typical Use Case Image generation Language, time-series Computer vision

🧠 One-Line Memory Trick

  • GAN = Create fake data
  • RNN = Remember the past
  • CNN = See patterns in images

🎯 Selection Guide

Question Mentions Choose
Generate images, fake data, deepfakes GAN
Time-series, text, speech, logs RNN
Images, vision, object detection CNN

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