mlib_ImageGradient3x3

- 3x3 gradient filter

Synopsis

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

mlib_status mlib_ImageGradient3x3(mlib_image *dst, const mlib_image *src,
     const mlib_d64 *hmask, const mlib_d64 *vmask, mlib_s32 cmask, mlib_edge edge);

Description

The mlib_ImageGradient3x3() function performs edge detection by computing the magnitude of the image gradient vector in two orthogonal directions using 3x3 gradient filtering.

It uses the following equation:

dst[x][y][i] = ( SH(x,y,i)**2 + SV(x,y,i)**2 )**0.5

where SH() and SV() are the horizontal and vertical gradient images generated from the corresponding channel of the source image by correlating it with the supplied orthogonal (horizontal and vertical) gradient masks.

Parameters

The function takes the following arguments:

dst

Pointer to destination image.

src

Pointer to source image.

hmask

Pointer to horizontal mask in row-major order.

vmask

Pointer to vertical mask in row-major order.

cmask

Channel mask to indicate the channels to be convolved, each bit of which represents a channel in the image. The channels corresponding to 1 bits are those to be processed. For a single channel image, the channel mask is ignored.

edge

Type of edge condition. It can be one of the following:

MLIB_EDGE_DST_NO_WRITE
MLIB_EDGE_DS_FILL_ZERO
MLIB_EDGE_DST_COPY_SRC
MLIB_EDGE_SR_EXTEND

Return Values

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

Attributes

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

See Also

mlib_ImageGradient3x3_Fp(3MLIB), mlib_ImageGradientMxN(3MLIB), mlib_ImageGradientMxN_Fp(3MLIB), attributes(5)