Satellite Composite Color Image

For multiband imagery, we display three bands in red, green, and blue, which is the color scheme for TV and computer displays. If we have red, green, and blue bands, we have a "true color" image. But we often have some infrared bands, and typically they contain valuable information (for example, the contrast between land and water is much clearer in the IR than in the visible, and vegetation reflects strongly in the IR). In contrast, the blue channel typically contains little of interest. Thus a typical "false color" scheme would show the green in blue, the red in green, and the IR in red, such as the center image below. On such a scene the vegetation shows up in red because its IR signature is so strong.

 

 

Annapolis Landsat TM Scene With Different Band Combinations

True color.  TM Bands 1, 2, 3 for the older Landsats, and 2,3,4 for Landsat 8.  This is a true color image. Note that the coastline does not show up clearly.  Band 1 in particular usually has limited information. False color. TM Bands 2, 3, 4 for the older Landsats, and 3,4,5 for Landsat 8.  This is a false color IR image, with the red being the near IR band (which we cannot see), but which clearly shows the vegetation and its health.  This may be the most common band combination used in remote sensing.  While it requires some training for users, it has the most information.  In addition to vegetation, it very clearly shows the difference between water and other features. TM bands 4, 5, and 7 for the older Landsats, all invisible to humans in the near to mid IR.  Any time a TM scene involves "unusual" colors like this blue or yellows or purple, it almost certainly means that the IR bands are being displayed.  One prominent use of these bands is to enhance geology.

Landsat 8 changed the bands substantially.


Last revision 4/23/2018