I. Introduction
The spot 4 satellite has collected images with spatial resolutions of 10 m in panchromatic mode and 20 m in multispectral mode. Its performance has been improved by adding a new short wave infrared (SWIR) spectral band and improving its operational stability. In environmental studies and agriculture, the sensitivity of the SWIR band to the variation of canopy or soil water content creates a strong contrast between soil and vegetation reflectance. It is, thus, easier to identify variations in canopy structure using the SPOT 4 SWIR band. This band is also significant for the discrimination of forest types, the classification of some crops and vegetation areas, estimation of bare soil-vegetation ratios, and detection of forest fires [1]–[5].