university computervision week1 theory

Histogram Equalization

Source:

Goal

Create a new image whose intensities are spread more evenly across the available range.

Core mapping

The lecture uses the normalized cumulative histogram as a lookup table:

Then each input value u is replaced by \phi(u).

Key idea

  • compute histogram
  • compute cumulative histogram
  • normalize it
  • use it as a lookup table for output intensities

This preserves intensity ordering while improving contrast.