Content-type: text/html Man page of mlib_ImageMulAlpha

# mlib_ImageMulAlpha

Section: mediaLib Library Functions (3MLIB)
Updated: 2 Mar 2007
Index Return to Main Contents

## NAME

mlib_ImageMulAlpha - alpha channel multiplication

## SYNOPSIS

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

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

## DESCRIPTION

The mlib_ImageMulAlpha() function multiplies 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.

## 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

## SEE ALSO

mlib_ImageMulAlpha_Inp(3MLIB), mlib_ImageMulAlpha_Fp(3MLIB), mlib_ImageMulAlpha_Fp_Inp(3MLIB), attributes(5)

## Index

NAME
SYNOPSIS
DESCRIPTION
PARAMETERS
RETURN VALUES
ATTRIBUTES
SEE ALSO

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Time: 02:38:12 GMT, October 02, 2010