Image Processing Online - Help Geoscience Australia

Updated: 21 April 2006

Suggested Band Combinations

Try the following band combinations by setting the red, green and blue colour bands as suggested:

red= band 3, green= band 2, blue= band 1 - This band combination looks similar to a normal aerial photograph.
red= band 7, green= band 4, blue= band 1 - This band combination provides the greatest contrast between bands and simulates natural colour.
red= band 7, green= band 5, blue= band 4 - This band combination provides good contrast between vegetation (blue) and rock (shades of orange and brown).
red= band 1, green= band 1, blue= band 1 - Making all colour guns the same band will give you a black and white scene of that band.

The Processing Method - Enhancing the Image

Try selecting Vegetation Index from the processing method table. This will process the scene using the Normalised Difference Vegetation Index (band4-band3)/(band4+band3), areas of dense vegetation appear in red, sparse vegetation in blue.

The Water Depth algorithm shows deeper water in blue and shallow water in red, but note that there are inaccuracies due to variations in the sea-foor reflectivity and due to suspended matter in the water column. This is an approximate algorithm only.

The Water Chloryphyll algorithm measures the amount of organic material present in the water column as a ratio of TM band 2/band 1. Water containing high levels of organic material appear in red, low organic concentrations are blue. Again, it should be remembered that these algorithms are approximate only.

NOTE: An understanding of the properties of marine and terrestrial materials and their interaction to produce a complex signal at the satellite sensor is required to properly analyse the processed imagery. Variability in scene contents will always result in subjective and relative accuracies of imagery.

Do not base important decisions on these satellite images.

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