mediaLib Library Functions              mlibImageDivAlpha(3MLIB)



NAME
     mlibImageDivAlpha - alpha channel division

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

     mlibstatus mlibImageDivAlpha(mlibimage *dst, const mlibimage *src,
          mlibs32 cmask);


DESCRIPTION
     The mlibImageDivAlpha() function divides color channels  by
     the alpha channel on a pixel-by-pixel basis.


     For the MLIBYTE image, it uses the following equation:

       dst[x][y][c] = src[x][y][c] / (src[x][y][a] * 2**(-8))



     For the MLIBSHORT image, it uses the following equation:

       dst[x][y][c] = src[x][y][c] / (src[x][y][a] * 2**(-15))



     For the MLIBUSHORT image, it uses the following equation:

       dst[x][y][c] = src[x][y][c] / (src[x][y][a] * 2**(-16))



     For the MLIBINT image, it uses the following equation:

       dst[x][y][c] = src[x][y][c] / (src[x][y][a] * 2**(-31))



     where c and a are the indices for the color channels and the
     alpha channel, respectively, so c != a.


     In the case of src[x][y][a] = 0,

       dst[x][y][c] = 0              if src[x][y][c] = 0
       dst[x][y][c] = DATATYPEMAX  if src[x][y][c] > 0
       dst[x][y][c] = DATATYPEMIN  if src[x][y][c] < 0






SunOS 5.11           Last change: 2 Mar 2007                    1






mediaLib Library Functions              mlibImageDivAlpha(3MLIB)



     where DATATYPE is MLIBU8, MLIBS16, MLIBU16, or  MLIBS32
     for  an image of type MLIBYTE, MLIBSHORT, MLIBUSHORT, or
     MLIBINT, respectively.

PARAMETERS
     The function takes the following arguments:

     dst      Pointer to destination image.


     src      Pointer to source image.


     cmask    Channel mask to indicate the  alpha  channel.  Each
              bit  of the mask represents a channel in the image.
              The channel corresponding to the 1 bit of cmask  is
              the alpha channel.


RETURN VALUES
     The function returns MLIBSUCES if  successful.  Otherwise
     it returns MLIBFAILURE.

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



     
           ATRIBUTE TYPE               ATRIBUTE VALUE       
    
     Interface Stability          Committed                   
    
     MT-Level                     MT-Safe                     
    


SEE ALSO
     mlibImageDivAlphaInp(3MLIB), mlibImageDivAlphaFp(3MLIB),
     mlibImageDivAlphaFpInp(3MLIB), attributes(5)














SunOS 5.11           Last change: 2 Mar 2007                    2