CNN

CNNs learn features from raw pixels: input feature map (width, height, RGB depth) and a stack of convolution, ReLU, pooling.

Intro to CNN.

https://developers.google.com/machine-learning/practica/image-classification/convolutional-neural-networks

Convoluted Neural Network. Breakthrough: progressively extract higher- and higher-level representations of the image content.

Instead of preprocessing the data to derive features like textures and shapes, a CNN takes just the image's raw pixel data as input and "learns" how to extract these features, and ultimately infer what object they constitute.

Input feature map

Matrix:

  • Width: image width.
  • Height: image height.
  • Depth: R, G, B.

Modules

A CNN comprises a stack of modules. Each module performs 3 tasks:

  1. Convolution.
  2. ReLU.
  3. Pooling.

Convoluted map

Convolution extracts tiles of the input feature map and applies filters. Two factors:

  1. Size of tile — typically 3x3 or 5x5.
  2. Depth: number of filters.

Application of filter:

Updated: 2026 Aug 26