COLOUR COMPOSITES in remote sensing.pptx

Colour composites in remote sensing

1. COLOUR COMPOSITES Submitted by

2. Contents Colour Composites True Colour Composit e False Colour Composite

3. Introduction Information contained in an optical image having colours are often utilized for image interpretation. “Colour is defined as the aspect of things that is caused by differing qualities of light being reflected or emitted by them.”

4. True Colour Composite If a multispectral image consists of the three visual primary colour bands the three bands may be combined to produce a "true colour" image. The colours of the resulting colour composite image resemble closely what would be observed by the human eyes.

5. False Colour Composite The most commonly seen false-color images display the very-near infrared as red, red as green, and green as blue. In this 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.

6. Other False colour composite scheme R = SWIR band (SPOT4 band 4, Landsat TM band 5) G = NIR band (SPOT4 band 3, Landsat TM band 4) B = Red band (SPOT4 band 2, Landsat TM band 3) In this display scheme, vegetation appears in shades of green. Bare soils and clear cut areas appear purplish or magenta. The patch of bright red area on the left is the location of active fires. A smoke plume originating from the active fire site appears faint bluish in colour. FCC of SPOT 4 multispectral image including the SWIR Band.

7. Advantages of FCC Allow us to visualize the wavelengths the human eye does not see (near the infrared range). The use of bands, such as near infrared, increases spectral separation and can enhance the interpretability of data. This band combination is valuable for gauging plant health . Plants reflect near infrared and green light, while absorbing red. Since they reflect more near infrared than green, plant covered land appears deep red. TCC FCC

8. Colour signatures on standard false colour Composite of Earth Surface Earth surface features Colours in standard FCC Earth surface features Colours in standard FCC Evergreen Red to magenta Clear water Dark blue to black Deciduous Brown to red Turbid water Light blue Scrubs Light brown with red patches Shallow ravines Light green Cropped land Pink to Bright red Wetlands Motelled black Fallow land Light blue to white Built up area High density Dark blue to bluish green Wetland vegetation Blue to grey low density Light blue

9. Applications of FCC The monitoring of forest fires. Surfaces with elevated temperatures, such as forest fires and calderas of volcanoes, saturate the image in medium IR channels and are displayed in shades of red or yellow. Study of vegetation health.

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