Multi-spectral image

From Wikipedia, the free encyclopedia

This article may require cleanup to meet Wikipedia's quality standards.
Please discuss this issue on the talk page or replace this tag with a more specific message.
This article has been tagged since December 2005.

The human eye has three colour receptors for red, green and blue. Multi-spectral images are images that are taken with additional receptors sensitive to other frequences of the visible light, or to frequencies beyond visible light, like the infrared region of electromagnetic continuum. This can allow to extract additional information that the human eye fails to capture.

Multi-spectral images are the main type of images acquired by Remote sensing (RS) radiometers. Multi-spectral is the opposite of panchromatic. Usually satellites have 3 to 7 or more radiometers (France's SPOT has 3, Landsat has 7). Each one acquires one digital image (in remote sensing, called a scene) in a small band of visible spectra, ranging 0.7 µm to 0.4 µm, called red-green-blue (RGB) region, and going to infra-red wavelengths of 0.7 µm to 10 or more µm, classified as NIR-Near InfraRed, MIR-Middle InfraRed and FIR-Far InfraRed or Thermal. In the Landsat case there are 7 scenes comprising a 7 band multi spectral image.