The C interface for erode. More...

afError	af_erode_B (bool d_out, unsigned in_ndims, const unsigned in_dims, const bool d_in, unsigned nhood_ndims, const unsigned nhood_dims, const bool *h_nhood, unsigned batch)
	Erode an Image. More...

afError	af_erode_S (float d_out, unsigned in_ndims, const unsigned in_dims, const float d_in, unsigned nhood_ndims, const unsigned nhood_dims, const float *h_nhood, unsigned batch)
	Single precision, Image Erosion. More...

afError	af_erode_D (double d_out, unsigned in_ndims, const unsigned in_dims, const double d_in, unsigned nhood_ndims, const unsigned nhood_dims, const double *h_nhood, unsigned batch)
	Double precision, Image Erosion. More...

Detailed Description

The C interface for erode.

The erosion function is a morphological transformation on an image that requires two inputs. The first is the image to be morphed, and the second is the mask indicating neighborhood that must be white in order to preserve each pixel.

In erode, for each pixel, the mask is centered at the pixel. If each pixel of the mask matches the corresponding pixel on the image, then no change is made. If there is at least one mismatch, then pixels are changed to the background color (black).

Erosion supports n-channel images (ie. 3D matrices). However a tile must be 2D and will be same for all channels. If you wish to use separate masks for channels, you can extract the channel, apply the operation and store the resulting channel back in the array.

Image erosion is useful for making edges more defined.

// Erode an image, 8-neighbor connectivity
array mask8 = constant(1,3, 3);
array img_out = erode(img_in, mask8);
// erode an image, 4-neighbor connectivity
const float h_mask4[] = { 0.0, 1.0, 0.0,
                          1.0, 1.0, 1.0,
                          0.0, 1.0, 0.0 };
array mask4 = array(3, 3, h_mask4);
array img_out = erode(img_in, mask4);

Original

Mask (8-neighbor connectivity)

Intermediate

Result

For further reference, you can look at the wikipedia page: Erosion (morphology)

Function Documentation

afError af_erode_B	(	bool *	d_out,
		unsigned	in_ndims,
		const unsigned *	in_dims,
		const bool *	d_in,
		unsigned	nhood_ndims,
		const unsigned *	nhood_dims,
		const bool *	h_nhood,
		unsigned	batch
	)

Erode an Image.

Parameters

[out]	d_out	The eroded image
[in]	in_ndims	Number of dimension elements in `in_dims`
[in]	in_dims	Dimensions of `d_in`
[in]	d_in	Input image
[in]	nhood_ndims	Number of dimension elements in `nhood_dims`
[in]	nhood_dims	Dimensions of `h_nhood`
[in]	h_nhood	neighborhood patch (on host)
[in]	batch	Number of input images (1 or ngfor)

Note: h_nhood must be square and odd (3x3,5x5,7x7,...)Boolean, Image Erosion

afError af_erode_S	(	float *	d_out,
		unsigned	in_ndims,
		const unsigned *	in_dims,
		const float *	d_in,
		unsigned	nhood_ndims,
		const unsigned *	nhood_dims,
		const float *	h_nhood,
		unsigned	batch
	)

Single precision, Image Erosion.

afError af_erode_D	(	double *	d_out,
		unsigned	in_ndims,
		const unsigned *	in_dims,
		const double *	d_in,
		unsigned	nhood_ndims,
		const unsigned *	nhood_dims,
		const double *	h_nhood,
		unsigned	batch
	)

Double precision, Image Erosion.