/*-------------------------------------------------------------------------*/
/**
   @file    median.h
   @author  N. Devillard
   @date    1998
   @version $Revision: 1.10 $
   @brief   Fast median finding routines.
*/
/*--------------------------------------------------------------------------*/

/*
    $Id: median.h,v 1.10 2001/11/07 14:45:27 yjung Exp $
    $Author: yjung $
    $Date: 2001/11/07 14:45:27 $
    $Revision: 1.10 $
*/

#ifndef _MEDIAN_H_
#define _MEDIAN_H_

/*---------------------------------------------------------------------------
   								Includes
 ---------------------------------------------------------------------------*/

/* Get the definition of a pixelvalue */
#include "local_types.h"

/*---------------------------------------------------------------------------
   							Function prototypes
 ---------------------------------------------------------------------------*/


/*-------------------------------------------------------------------------*/
/**
  @brief    Find the kth smallest element in an array.
  @param    a   Array to consider for median search.
  @param    n   Number of elements in the array.
  @param    k   Rank of the element to find (between 0 and n-1).
  @return   One element from the array.

  Provide an array of n pixelvalues and the rank of the value you want
  to find. A rank of 0 means the minimum element, a rank of n-1 is the
  maximum element, and a rank of n/2 is the median. Use the
  median_WIRTH macro to find the median directly.

  NB: The input array is modified. Some elements are swapped, until
  the requested value is found. The array is left in an undefined
  sorted state.
  
  This algorithm was taken from the following book:
  \begin{verbatim}
                Author: Wirth, Niklaus 
                 Title: Algorithms + data structures = programs 
             Publisher: Englewood Cliffs: Prentice-Hall, 1976 
  Physical description: 366 p. 
                Series: Prentice-Hall Series in Automatic Computation 
  \end{verbatim}
 */
/*--------------------------------------------------------------------------*/
pixelvalue
kth_smallest(pixelvalue a[], int n, int k) ;


/*-------------------------------------------------------------------------*/
/**
  @brief    Optimized search of the median of 3 values.
  @param    p   Array of 3 pixelvalues
  @return   Median of the input values.

  Found on sci.image.processing. Cannot go faster unless some
  assumptions are made about the nature of the input signal, or the
  underlying hardware.

  The input array is modified.
 */
/*--------------------------------------------------------------------------*/
pixelvalue
opt_med3(pixelvalue * p) ;


/*-------------------------------------------------------------------------*/
/**
  @brief    Optimized search of the median of 5 values.
  @param    p   Array of 5 pixelvalues
  @return   Median of the input values.

  Found on sci.image.processing. Cannot go faster unless some
  assumptions are made about the nature of the input signal, or the
  underlying hardware.

  The input array is modified.
 */
/*--------------------------------------------------------------------------*/
pixelvalue
opt_med5(pixelvalue * p) ;


/*-------------------------------------------------------------------------*/
/**
  @brief    Optimized search of the median of 7 values.
  @param    p   Array of 7 pixelvalues
  @return   Median of the input values.

  Found on sci.image.processing. Cannot go faster unless some
  assumptions are made about the nature of the input signal, or the
  underlying hardware.

  The input array is modified.
 */
/*--------------------------------------------------------------------------*/
pixelvalue
opt_med7(pixelvalue * p) ;


/*-------------------------------------------------------------------------*/
/**
  @brief    Optimized search of the median of 9 values.
  @param    p   Array of 9 pixelvalues
  @return   Median of the input values.

  Formula from:
  \begin{verbatim}
  XILINX XCELL magazine, vol. 23 by John L. Smith
  \end{verbatim}

  The result array is guaranteed to contain the median value in middle
  position, but other elements are NOT sorted.

  The input array is modified.
 */
/*--------------------------------------------------------------------------*/
pixelvalue
opt_med9(pixelvalue * p) ;


/*-------------------------------------------------------------------------*/
/**
  @brief    Optimized search of the median of 25 values.
  @param    p   Array of 25 pixelvalues
  @return   Median of the input values.

  Formula from:
  \begin{verbatim}
  Graphic Gems source code
  \end{verbatim}

  The result array is guaranteed to contain the median value in middle
  position, but other elements are NOT sorted.

  The input array is modified.
 */
/*--------------------------------------------------------------------------*/
pixelvalue
opt_med25(pixelvalue * p) ;


/*-------------------------------------------------------------------------*/
/**
  @brief    Compute the median pixel value of an array.
  @param    a   Array to consider.
  @param    n   Number of pixels in the array.
  @return   The median of the array.

  This is the generic method that should be called to get the median
  out of an array of pixelvalues. It calls in turn the most efficient
  method depending on the number of values in the array.

  The input array is always modified.
 */
/*--------------------------------------------------------------------------*/
pixelvalue
median_pixelvalue(pixelvalue * a, int n) ;

#endif