What is a Convolutional Neural Network (CNN) and how does it extract features from images?

Updated May 16, 2026

Short answer

CNNs are neural networks designed to process grid-like data such as images by learning spatial hierarchies of features using convolutional filters.

Deep explanation

Convolutional Neural Networks (CNNs) revolutionized computer vision by enabling automatic feature extraction from raw pixels.

Core idea: Instead of manually designing features, CNNs learn filters that detect patterns such as edges, textures, and shapes.

Key components:

  1. Convolution Layers:
  • Apply learnable filters across input images.
  • Detect spatial patterns.
  1. Filters/Kernels:
  • Small matrices (e.g., 3x3).
  • Slide across image producing feature maps.
  1. Feature Maps:
  • Output of convolution operation.
  1. Activation Functions:
  • Introduce non-linearity (ReLU).

5.…

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