opensolaris man page for mlib_imagedivalpha

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  corresponding	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	     |Committed 		   |
       +-----------------------------+-----------------------------+
       |MT-Level		     |MT-Safe			   |
       +-----------------------------+-----------------------------+

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

SunOS 5.11							    2 Mar 2007						 mlib_ImageDivAlpha(3MLIB)