3.5 - RGB images

RGB images can be used to extract information about vegetation cover. RGB techniques work by associating a colour to a particular channel.To extract maximum information from a single image each colour (Red, Green or Blue) should be associate to a different channel with distinct physical properties.

To extract information about vegetation cover, the RGB composite 1.6; 0.8; 0.6 μm, often referred as "Day natural colours" composite, can be used.

In this composite Red is associated to NIR 1.6 μm; Green to VIS 0.8 μm and Blue to VIS 0.6 μm. So as you can see in the image:

Figure 3.12 – Meteosat-9 colour composite image of 1.6μm; 0.8μm and 0.6 μm

  • Reddish/pink is dominant for bare soil and arid regions.
  • Green is the dominant component for vegetation.
  • Cyan is evident in ice clouds.

A complete description of how to apply RGB techniques in satellite images and forecasting, can be found in www.zamg.ac.at/eumetrain/CAL_Modules/CALRGB/

Based on what you have learned so far, try to interpret this RGB image in terms of some main features on the global distribution of vegetation. Drag the adequate labels to the right spot in the image: