Manual Pages for UNIX Operating System command usage for man mlib_ImageExtremaLocations

mediaLib Library Functions      mlib_ImageExtremaLocations(3MLIB)



NAME
     mlib_ImageExtremaLocations, mlib_ImageExtremaLocations_Fp  -
     image extrema and their locations

SYNOPSIS
     cc [ flag... ] file... -lmlib [ library... ]
     #include 

     mlib_status mlib_ImageExtremaLocations( mlib_s32 *min, mlib_s32 *max,
          const mlib_image *img, mlib_s32 xStart, mlib_s32 yStart,
          mlib_s32 xPeriod, mlib_s32 yPeriod, mlib_s32 saveLocations,
          mlib_s32 maxRuns, mlib_s32 *minCounts, mlib_s32 *maxCounts,
          mlib_s32 **minLocations, mlib_s32 **maxLocations, mlib_s32 len);


     mlib_status mlib_ImageExtremaLocations_Fp( mlib_d64 *min, mlib_d64 *max,
          const mlib_image *img, mlib_s32 xStart, mlib_s32 yStart,
          mlib_s32 xPeriod, mlib_s32 yPeriod, mlib_s32 saveLocations,
          mlib_s32 maxRuns, mlib_s32 *minCounts, mlib_s32 *maxCounts,
          mlib_s32 **minLocations, mlib_s32 **maxLocations, mlib_s32 len);


DESCRIPTION
     Each of the functions finds the image-wise minimum and  max-
     imum  pixel  values  for each channel, and optionally, their
     locations.


     Each of the functions scans an image, finds the minimum  and
     maximum  pixel  values for each channel, and finds the loca-
     tions of those pixels with the minimum or maximum values.


     The user provides initial minimum/maximum values through the
     arguments min and max.  This function will update them based
     on findings.


     The set of pixels scanned  may  furthermore  be  reduced  by
     specifying  xPeriod  and yPeriod parameters that specify the
     sampling rate along each axis.


     The set of pixels to be scanned may  be  obtained  from  the
     following equation:

       x = xStart + p*xPeriod;  0 < p < (w - xStart)/xPeriod
       y = yStart + q*yPeriod;  0 < q < (h - yStart)/yPeriod







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mediaLib Library Functions      mlib_ImageExtremaLocations(3MLIB)



     The locations of the minimum/maximum, if asked, are recorded
     in  a  format of run-length coding. Each run-length code, or
     simply called a  run,  has  a  format  of  (xStart,  yStart,
     length).  Here length is defined on the low-resolution image
     (with downsampling factors of 1/xPeriod, 1/yPeriod) and does
     not  cross  rows.  So  the  run-length code (xStart, yStart,
     length) means that the pixels at (xStart, yStart), (xStart +
     xPeriod,  yStart),  ...,  (xStart  +  (length  - 1)*xPeriod,
     yStart)  of  the  original  image  have  a  value   of   the
     minimum/maximum.


     The buffers for minLocations and maxLocations are  organized
     in the following format for each channel i:

       minLocations[i][0] = xStart0;  // the 1st run
       minLocations[i][1] = yStart0;
       minLocations[i][2] = length0;
       minLocations[i][3] = xStart1;  // the 2nd run
       minLocations[i][4] = yStart1;
       minLocations[i][5] = length1;
                   ......             // more runs
       minLocations[i][len-1] = ...;



     It is the user's responsibility to  allocate  enough  memory
     for  the  buffers  for  minLocations and maxLocations.  This
     function may return MLIB_OUTOFRANGE, if any of  the  buffers
     is not big enough.

PARAMETERS
     The function takes the following arguments:

     min              Pointer to the minimum values.


     max              Pointer to the maximum values.


     img              Pointer to the input image.


     xStart           Initial X sample coordinate.


     yStart           Initial Y sample coordinate.


     xPeriod          X sampling rate. xPeriod > 1.





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mediaLib Library Functions      mlib_ImageExtremaLocations(3MLIB)



     yPeriod          Y sampling rate. yPeriod > 1.


     saveLocations    If true (i.e., saveLocations  !=  0),  find
                      the  extrema locations; otherwise only find
                      the extrema.


     maxRuns           Number of runs of the minimum/maximum  the
                      caller  expects for each channel. maxRuns >
                      1.  If  it   is   MLIB_S32_MAX,   all   the
                      minimum/maximum    locations    should   be
                      recorded.


     minCounts        Pointer to  the  numbers  of  runs  of  the
                      minimum recorded in minLocations.


     maxCounts        Pointer to the numbers of runs of the  max-
                      imum recorded in maxLocations.


     minLocations     Pointer to the minimum locations in a  for-
                      mat of run-length coding.


     maxLocations     Pointer to the maximum locations in a  for-
                      mat of run-length coding.


     len              Length   of    the    buffers    for    the
                      minimum/maximum locations in each channel.


RETURN VALUES
     The function returns MLIB_SUCCESS if  successful.  Otherwise
     it returns MLIB_FAILURE.

ATTRIBUTES
     See attributes(5) for descriptions of the  following  attri-
     butes:













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mediaLib Library Functions      mlib_ImageExtremaLocations(3MLIB)



     ____________________________________________________________
    |       ATTRIBUTE TYPE        |       ATTRIBUTE VALUE       |
    |_____________________________|_____________________________|
    | Interface Stability         | Committed                   |
    |_____________________________|_____________________________|
    | MT-Level                    | MT-Safe                     |
    |_____________________________|_____________________________|


SEE ALSO
     mlib_ImageExtrema2(3MLIB),         mlib_ImageMaximum(3MLIB),
     mlib_ImageMaximum_Fp(3MLIB),       mlib_ImageMinimum(3MLIB),
     mlib_ImageMinimum_Fp(3MLIB), attributes(5)










































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