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Preprocessing

In order to view and analyse images of remote sensing systems, they have to be preprocessed first. This is due to the fact that the radiation that reaches the satellite sensor is influenced by many phenomena that cause radiometric and geometric distortion. To compensate these distortions, radiometric and geometric correction is needed. To simplify visual analyses, contrast and acuity of an image can be altered. The work stages before image data can be analysed is called preprocessing.

 

 

 

The atmospheric correction tries to subtract the influence of the atmosphere out of the image. Without this technique of image processing it would be impossible to draw inferences from the data about the spectral characteristics of the land surface.


The geometric correction of an image compensates distortions. This means, that the distorted image is assigned a standardised geometry, i.e. coordinates.

Visual correction includes, among other things, the field of blurring or sharpening as well as highlighting edges and lines. This kind of image processing aids visual analyses.