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Terminology. Remote Sensing

Absorptance : The ratio of the radiant energy absorbed by a substance to the energy
it receives.

Band : The specific wavelength interval in the electromagnetic spectrum.

Digital image : An array of digital numbers (DN) arranged in rows and columns,
having the property of an intensity value and their locations.

Digital Number : An intensity value of a pixel in a digital image.

Digital Image Processing : The numerical manipulation of DN values for the purpose
of extracting information about the phenomena of the surface they represent.

Electromagnetic Radiation (EMR) : The Energy propagated through a space or a
medium at a speed of light.

Electromagnetic Spectrum : The continuum of EMR that ranges from short wave
high frequency cosmic radiations to long wavelength low frequency radio waves.

False Colour Composite (FCC) : An artificially generated colour image in which
blue, green and red colours are assigned to the wavelength regions to which they do
not belong in nature. For example, in standard a False Colour Composite blue is
assigned to green radiations (0.5 to 0.6 µm), green is assigned to red radiations (0.6
to 0.7 µm and red is assigned to Near Infrared radiation (0.7 to 0.8 µm).

Gray scale : A medium to calibrate the variations in the brightness of an image that
ranges from black to white with intermediate grey values.

Image : The permanent record of a scene comprising of natural and man-made
features and activities, produced by photographic and non–photographic means.

Scene : The ground area covered by an image or a photograph.

Sensor : Any imaging or non–imaging device that receives EMR and converts it into
a signal that can be recorded and displayed as photographic or digital image.

Reflectance : The ratio of the radiant energy reflected by a substance to the energy
it receives.

Spectral Band : The range of the wavelengths in the continuous spectrum such as
the green band ranges from 0.5 to .6 µ and the range of NIR band 0.7 to 1.1 µ.




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