LAND - Land cover

Global land cover of Africa.
Spot 4/Vegetation (2000).
Source: Global Land Cover 2000 database. European Commission, Joint Research Centre, 2003.
Useful information at global level
Many people think Africa is all rainforest or deserts. This map tells the truth !
The left image is a mosaic image, obtained by putting together thousands of images. Single cloud-free images were combined in a huge mosaic of the continent.
The right image was classified to highlight the main surface cover types (desert, forest, savannah, etc.).
Click here to get the colour legend.
Question: How was the classified image obtained ?