Based on colour in image we differentiate the features of earth. and I'd like to know which colour represents what. And I'd like to know for true color image, false color image.
Transmitted light, or Additive Color (RGB wavelengths) begins with the absence of light, or Black. When wavelengths of RGB are combined, at full strength it creates white. e.g. your TV, or computer monitor colors. (Sharma, 2004). Printed materials use a Subtractive Color (CMYK inks/toners) and start with a substrate, for example a white paper. As the cyan, magenta, and yellow inks are added the density of the inks build on each other. Therefore creating a dense color, almost black. (Sharma, 2004). So your true or false color could be created differently. It depends if you are looking at a printed image or an image on a computer, to how the color was added or converted.
Understanding Color Management by Abhay Sharma, Thompson Publishing
Please refer to the web links, as it will assist with specifics for your answer.
http://earthobservatory.nasa.gov/Features/FalseColor/page6.php
http://www.allthesky.com/articles/imagecolor.html
False color in an image is a post-processing technique to enhance some desired features to be perceived by an human observer. E.G., gray tone images induce visual confusion, so false colors are assigned to certain gray levels for enhancement purposes. False color is introduced "a posteriori" to reveal some feature, already segmented before. Be careful with artifacts, which is another source of different colors caused by detection / acquisition issues.
False color representation is normally used to represent hyperspectral data. That data contain band above 700 nm, which are not visible to human eye, therefor false color representation is used. In this case, living organisms like trees and grass may appear red because of their reluctance in bands above visible range.
I think Khan's and mine answers show the motivations of false colors uses.
There is an explicit information regarding your question on these sites: http://web.pdx.edu/~emch/ip1/bandcombinations.html
https://earthobservatory.nasa.gov/features/FalseColor/page6.php
True color uses the Red, Green and Blue Color normally termed the (RGB). The imaged composed will be showing the natural colors that would be observed by our eyes. For example vegetation is green that means vegetation will be depicted by the green color . This is exactly the color our camera would show when taking photos.
False color would also use the RGB and other colours and the colours use would not be the true reflection of what we see with our eyes . Example vegetation can be depicted with red colour or grey colour under the grey scale.
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