mlib_ImageDivAlpha(3MLIB)				    mediaLib Library Functions					 mlib_ImageDivAlpha(3MLIB)

NAME

       mlib_ImageDivAlpha - alpha channel division

SYNOPSIS

       cc [ flag... ] file... -lmlib [ library... ]
       #include <mlib.h>

       mlib_status mlib_ImageDivAlpha(mlib_image *dst, const mlib_image *src, mlib_s32 cmask);

DESCRIPTION

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

       For the MLIB_BYTE image, it uses the following equation:

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

       For the MLIB_SHORT image, it uses the following equation:

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

       For the MLIB_USHORT image, it uses the following equation:

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

       For the MLIB_INT 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] = DATA_TYPE_MAX  if src[x][y][c] > 0
       dst[x][y][c] = DATA_TYPE_MIN  if src[x][y][c] < 0

       where  DATA_TYPE  is MLIB_U8, MLIB_S16, MLIB_U16, or MLIB_S32 for an image of type MLIB_BYTE, MLIB_SHORT, MLIB_USHORT, or MLIB_INT, respec-
       tively.

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 correspond-
		       ing to the 1 bit of cmask is the alpha channel.

RETURN VALUES

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

ATTRIBUTES

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Interface Stability	     |Evolving			   |
       +-----------------------------+-----------------------------+
       |MT-Level		     |MT-Safe			   |
       +-----------------------------+-----------------------------+

SEE ALSO

       mlib_ImageDivAlpha_Inp(3MLIB), mlib_ImageDivAlpha_Fp(3MLIB), mlib_ImageDivAlpha_Fp_Inp(3MLIB), attributes(5)

SunOS 5.10							    10 Nov 2004 					 mlib_ImageDivAlpha(3MLIB)