Describe BRT1 here.

      FUNCTION BRT1(Z,Z0,KK,DN,ESZ)

 Calculates the brightness DN of a pixel in the image using maplet coordinates.
Confidence - 50%

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 * Return value :  
 
 Brightness value at a specific point Z


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*       DOUBLE PRECISION      Z(2)
 Pixel/Line within the image of the center of the maplet
 Passed in
 

*       INTEGER               Z0(2)
 X and Y within the maplet of the location to sample.
 Passed in

*       INTEGER               KK
 Movement rate in image space for each step in maplet space.
 Passed in

*       INTEGER               DN(-1300:1300,-1300:1300)
 DN of the image.  Passed in.

*       INTEGER               ESZ
 Size of maplet.  Used to check boundaries
 Passed in


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categorySubroutine