Functions
regions
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Find blobs in given image. More...

Functions

AFAPI array regions (const array &in, const af::connectivity connectivity=AF_CONNECTIVITY_4, const dtype type=f32)
 C++ Interface for getting regions in an image. More...
 
AFAPI af_err af_regions (af_array *out, const af_array in, const af_connectivity connectivity, const af_dtype ty)
 C Interface for regions in an image. More...
 

Detailed Description

Find blobs in given image.

Given a binary image (with zero representing background pixels), regions computes a floating point image where each connected component is labeled from 1 to N, the total number of components in the image.

A component is defined as one or more nonzero pixels that are connected by the specified connectivity (either 4-way(AF_CONNECTIVITY_4) or 8-way(AF_CONNECTIVITY_8)) in two dimensions.

regions_8conn.jpg
An example input and output for 8-connectivity

The default connectivity is AF_CONNECTIVITY_4.

Function Documentation

AFAPI af_err af_regions ( af_array *  out,
const af_array  in,
const af_connectivity  connectivity,
const af_dtype  ty 
)

C Interface for regions in an image.

Parameters
[out]outarray will have labels indicating different regions
[in]inarray should be binary image of type b8
[in]connectivitycan take one of the following [AF_CONNECTIVITY_4 | AF_CONNECTIVITY_8]
[in]tyis type of output array
Returns
AF_SUCCESS if the regions are identified successfully, otherwise an appropriate error code is returned.
AFAPI array af::regions ( const array &  in,
const af::connectivity  connectivity = AF_CONNECTIVITY_4,
const dtype  type = f32 
)

C++ Interface for getting regions in an image.

Below given are sample input and output for each type of connectivity value for type

Example for type == AF_CONNECTIVITY_8 Example for type == AF_CONNECTIVITY_4
af::array in(8, 8, input);
//af_print(in);
// in =
// 0 0 0 0 1 0 1 0
// 0 0 0 0 0 0 1 1
// 0 1 0 1 0 0 0 0
// 0 0 1 0 1 1 0 1
// 1 1 0 0 0 1 0 1
// 0 0 0 1 0 0 0 1
// 0 0 0 0 1 0 0 1
// 0 1 0 0 0 1 0 0
// Compute the label matrix using 8-way connectivity
af::array out = regions(in.as(b8), AF_CONNECTIVITY_8);
//af_print(out);
// 0 0 0 0 4 0 5 0
// 0 0 0 0 0 0 5 5
// 0 1 0 1 0 0 0 0
// 0 0 1 0 1 1 0 6
// 1 1 0 0 0 1 0 6
// 0 0 0 3 0 0 0 6
// 0 0 0 0 3 0 0 6
// 0 2 0 0 0 3 0 0
af::array in(8, 8, input);
//af_print(in.T());
//in
//0 0 0 0 1 0 1 0
//0 0 0 0 0 0 1 1
//0 1 0 1 0 0 0 0
//0 0 1 0 1 1 0 1
//1 1 0 0 0 1 0 1
//0 0 0 1 0 0 0 1
//0 0 0 0 1 0 0 1
//0 1 0 0 0 1 0 0
// Compute the label matrix using 4-way connectivity
af::array out = regions(in.as(b8), AF_CONNECTIVITY_4);
//af_print(out.T());
//out
//0 0 0 0 7 0 11 0
//0 0 0 0 0 0 11 11
//0 2 0 5 0 0 0 0
//0 0 4 0 8 8 0 12
//1 1 0 0 0 8 0 12
//0 0 0 6 0 0 0 12
//0 0 0 0 9 0 0 12
//0 3 0 0 0 10 0 0
Parameters
[in]inarray should be binary image of type b8
[in]connectivitycan take one of the following [AF_CONNECTIVITY_4 | AF_CONNECTIVITY_8]
[in]typeis type of output array
Returns
returns array with labels indicating different regions. Throws exceptions if any issue occur.