<P> In addition, variants of false color such as pseudocolor, density slicing, and choropleths are used for information visualization of either data gathered by a single grayscale channel or data not depicting parts of the electromagnetic spectrum (e.g. elevation in relief maps or tissue types in magnetic resonance imaging). </P> <P> To understand false color, a look at the concept behind true color is helpful . An image is called a true - color image when it offers a natural color rendition, or when it comes close to it . This means that the colors of an object in an image appear to a human observer the same way as if this observer was to directly view the object: A green tree appears green in the image, a red apple red, a blue sky blue, and so on . When applied to black - and - white images, true - color means that the perceived lightness of a subject is preserved in its depiction . </P> <P> Absolute true - color rendering is impossible . There are three major sources of color error (metameric failure): </P> <Ul> <Li> Different spectral sensitivities of the human eye and of an image capture device (e.g. a camera). </Li> <Li> Different spectral emissions / reflections of the object and of the image render process (e.g. a printer or monitor). </Li> <Li> Differences in spectral irradiance in the case of reflective images (e.g. photo prints) or reflective objects--see color rendering index (CRI) for details . </Li> </Ul>

What information do the pseudocolor images provide that you cannot get from the natural color image