DistanceTransform

Calculates the distance from each non-zero pixel to the nearest zero pixel within the source image.

The function interface is declared as follows:

HmppResult HMPPI_DistanceTransform_3x3_8u32f_C1R(const uint8_t* pSrc, int srcStep, float* pDst, int dstStep, HmppiSize roiSize, float* pMetrics);

pMetrics can be defined as follows:

Manhattan distance

Ipp32f pMetrics[3*3] = {
     1, 1, 1,
     1, 0, 1,
     1, 1, 1 
};

Euclidean distance

Ipp32f pMetrics[3*3] = {
     1.4142f, 1.0f, 1.4142f,
     1.0f,    0.0f, 1.0f,
     1.4142f, 1.0f, 1.4142f
 };

Parameters

Parameter	Description	Value Range	Input/Output
pSrc	Pointer to the source vector	The value cannot be NULL.	Input
srcStep	Distance between starts of consecutive lines in the source image, in bytes	(0, INT_MAX]	Input
pDst	Pointer to the destination vector	The value cannot be NULL.	Output
dstStep	Distance between starts of consecutive lines in the destination image, in bytes	(0, INT_MAX]	Input
roiSize	Size of the ROI of the source and destination images, in pixels	roiSize.width ∈ (0, INT_MAX], roiSize.height ∈ (0, INT_MAX]	Input
pMetrics	Pointer to a user-defined neighborhood cost table used to customize distance propagation rules	The value cannot be NULL.	Input

Return Value

Success: HMPP_STS_NO_ERR
Failure: An error code is returned.

Error Codes

Error Code	Description
HMPP_STS_NULL_PTR_ERR	The value of pSrc, pDst, or pMetrics is NULL.
HMPP_STS_STEP_ERR	The value of srcStep is less than or equal to 0.
HMPP_STS_SIZE_ERR	The value of roiSize.width or roiSize.height is less than or equal to 0.

Example

#include <stdio.h>
#include "hmppi.h"
#include "hmpp_type.h"
void DistanceTransformExample()
{
    HmppiSize roi = {5, 7};
    uint8_t src[45] = {1, 2, 3, 4, 5,
                       1, 2, 3, 4, 5,
                       1, 2, 3, 4, 5,
                       1, 2, 3, 4, 5,
                       1, 2, 3, 4, 5,
                       1, 2, 3, 4, 5,
                       1, 2, 3, 4, 5,
                       1, 2, 3, 4, 5,
                       1, 2, 3, 4, 5
                      };
    float dst[49] = {0};
    int32_t srcStep = 5 * sizeof(uint8_t);
    int32_t dstStep = 7 * sizeof(float);
    float pMetrics[3*3] = {
        1, 1, 1,
        1, 0, 1,
        1, 1, 1 
    };
    HmppResult res = HMPPI_DistanceTransform_3x3_8u32f_C1R(src, srcStep, dst, dstStep, roi, pMetrics);
    printf("result: %d\n", (int)res);
    for (int i = 0; i < 7; i++) {
        for (int j = 0; j < 7; j++) {
            printf("%f ", dst[i * 7 + j]);
        }
        printf("\n");
    }
}
int main()
{
    DistanceTransformExample();
    return 0;
}

Output:

result: 0
1.00 2.00 3.00 2.00 2.00 0.00 0.00 
1.00 2.00 3.00 2.00 1.00 0.00 0.00 
1.00 2.00 3.00 2.00 1.00 0.00 0.00 
1.00 2.00 3.00 2.00 1.00 0.00 0.00 
1.00 2.00 3.00 2.00 1.00 0.00 0.00 
1.00 4.00 3.00 2.00 1.00 0.00 0.00 
5.00 4.00 3.00 2.00 1.00 0.00 0.00

Parent topic: Image Statistics