The display colour assignment for any band of a multispectral In case, the colour of a target in the displayed image does not have any resemblance to its actual colour. The resulting product is known as a false colour composite image. some scheme may be more suitable for detecting certain objects in the image.
A very common false colour composite scheme for displaying a SPOT multispectral image is shown below:
R = XS3 (NIR band)
G = XS2 (red band)
B = XS1 (green band)
This false colour composite scheme allows vegetation to be detected readily in the image. In this type of false colour composite images, vegetation appears in different shades of red depending on the types and conditions of the vegetation, since it has a high reflectance in the NIR band (as shown in the graph of spectral reflectance signature).
Clear water appears dark-bluish (higher green band reflectance), while turbid water appears cyan (higher red reflectance due to sediments) compared to clear water. Bare soils, roads and buildings may appear in various shades of blue, yellow or grey, depending on their composition.