Canny

Intel® Integrated Performance Primitives Developer Guide and Reference

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ID 790148

Date 11/07/2023

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Canny

Implements Canny algorithm for edge detection.

Syntax

IppStatus ippiCanny_16s8u_C1R(Ipp16s* pSrcDx, int srcDxStep, Ipp16s* pSrcDy, int srcDyStep, Ipp8u* pDstEdges, int dstEdgeStep, IppiSize roiSize, Ipp32f lowThreshold, Ipp32f highThreshold, Ipp8u* pBuffer);

IppStatus ippiCanny_32f8u_C1R(Ipp32f* pSrcDx, int srcDxStep, Ipp32f* pSrcDy, int srcDyStep, Ipp8u* pDstEdges, int dstEdgeStep, IppiSize roiSize, Ipp32f lowThreshold, Ipp32f highThreshold, Ipp8u* pBuffer);

Platform-aware functions

IppStatus ippiCanny_16s8u_C1R_L(Ipp16s* pSrcDx, IppSizeL srcDxStep, Ipp16s* pSrcDy, IppSizeL srcDyStep, Ipp8u* pDstEdges, IppSizeL dstEdgeStep, IppiSizeL roiSize, Ipp32f lowThreshold, Ipp32f highThreshold, IppNormType norm, Ipp8u* pBuffer);

IppStatus ippiCanny_32f8u_C1R_L(Ipp32f* pSrcDx, IppSizeL srcDxStep, Ipp32f* pSrcDy, IppSizeL srcDyStep, Ipp8u* pDstEdges, IppSizeL dstEdgeStep, IppiSizeL roiSize, Ipp32f lowThreshold, Ipp32f highThreshold, IppNormType norm, Ipp8u* pBuffer);

Include Files

ippcv.h

Flavors with the _L suffix: ippcv_l.h

Domain Dependencies

Headers: ippcore.h, ippvm.h, ipps.h, ippi.h

Libraries: ippcore.lib, ippvm.lib, ipps.lib, ippi.lib

Parameters

pSrcDx: Pointer to the source image ROI x-derivative.
srcDxStep: Distance in bytes between starts of consecutive lines in the source image pSrcDx.
pSrcDy: Pointer to the source image ROI y-derivative.
srcDyStep: Distance, in bytes, between the starting points of consecutive lines in the source image pSrcDy.
pDstEdges: Pointer to the output array of the detected edges.
dstEdgeStep: Distance, in bytes, between the starting points of consecutive lines in the output image.
roiSize: Size of the source image ROI in pixels.
lowThreshold: Lower threshold for edges detection.
highThreshold: Upper threshold for edges detection.
norm: Normalization type; supported values: ippNormL1 and ippNormL2.
pBuffer: Pointer to the pre-allocated temporary buffer.

Description

This function operates with ROI (see Regions of Interest in Intel IPP). This function finds edges in the source image ROI and stores them into the output image pDstEdges using the Canny algorithm. The function requires a temporary working buffer; its size should be computed previously by calling the function ippiCannyGetSize.

Return Values

ippStsNoErr	Indicates no error. Any other value indicates an error or a warning.
ippStsNullPtrErr	Indicates an error condition if one of the specified pointers is `NULL`.
ippStsSizeErr	Indicates an error condition if pRoiSize has a field with zero or negative value.
ippStsStepErr	Indicates an error condition if srcDxStep, srcDyStep or dstEdgeStep is less than roi.width*<pixelSize>.
ippStsBadArgErr	Indicates an error when lowThresh is negative or highThresh is less than lowThresh.
ippStsNotEvenStepErr	Indicates an error condition if one of the step values is not divisible by 2 for 16s images, and by 4 for 32f images.

Example

/*******************************************************************************
* Copyright 2015 Intel Corporation.
*
*
* This software and the related documents are Intel copyrighted materials, and your use of them is governed by
* the express license under which they were provided to you ('License'). Unless the License provides otherwise,
* you may not use, modify, copy, publish, distribute, disclose or transmit this software or the related
* documents without Intel's prior written permission.
* This software and the related documents are provided as is, with no express or implied warranties, other than
* those that are expressly stated in the License.
*******************************************************************************/

// A simple example of the edge detection algorithm implemented with Intel(R) Integrated Primitives (Intel(R) IPP) functions:
//     ippiFilterSobelNegVertBorder_8u16s_C1R
//     ippiFilterSobelHorizBorder_8u16s_C1R
//     ippiCanny_16s8u_C1R


#include <stdio.h>
#include "ipp.h"

#define WIDTH  128  /* image width */
#define HEIGHT  64  /* image height */
#define THRESH_LOW    50.f /* Low   threshold for edges detection */
#define THRESH_HIGHT 150.f /* Upper threshold for edges detection */
#define BORDER_VAL 0

/* Next two defines are created to simplify code reading and understanding */
#define EXIT_MAIN exitLine:                                  /* Label for Exit */
#define check_sts(st) if((st) != ippStsNoErr) goto exitLine; /* Go to Exit if Intel(R) IPP function returned status different from ippStsNoErr */

/* Results of ippMalloc() are not validated because Intel(R) IPP functions perform bad arguments check and will return an appropriate status  */

int main(void)
{
    IppStatus status = ippStsNoErr;
    Ipp8u* pSrc = NULL, *pDst = NULL;  /* Pointers to source/destination images */
    int srcStep = 0, dstStep = 0;      /* Steps, in bytes, through the source/destination images */
    IppiSize roiSize = { WIDTH, HEIGHT }; /* Size of source/destination ROI in pixels */

    int iTmpBufSizeSobV  = 0;
    int iTmpBufSizeSobH  = 0;
    int iTmpBufSizeCanny = 0;
    int iTmpBufSize = 0;         /* Common work buffer size */
    int  dxStep = 0, dyStep = 0; /* Steps, in bytes, through buffer_dx/buffer_dy */
    Ipp8u *buffer = NULL;        /* Pointer to the common work buffer */
    Ipp16s* buffer_dx = NULL, *buffer_dy = NULL; /* Pointer to the buffer for first derivatives with respect to X / Y */

    pSrc = ippiMalloc_8u_C1(roiSize.width, roiSize.height, &srcStep);
    pDst = ippiMalloc_8u_C1(roiSize.width, roiSize.height, &dstStep);

    /* Start Edge Detection algorithm */
    {
        buffer_dx = ippiMalloc_16s_C1(roiSize.width, roiSize.height, &dxStep);
        buffer_dy = ippiMalloc_16s_C1(roiSize.width, roiSize.height, &dyStep);

        check_sts(  status = ippiFilterSobelVertBorderGetBufferSize(roiSize, ippMskSize3x3, ipp8u, ipp16s, 1, &iTmpBufSizeSobV) )
        check_sts(  status = ippiFilterSobelHorizBorderGetBufferSize(roiSize, ippMskSize3x3, ipp8u, ipp16s, 1, &iTmpBufSizeSobH) )

        check_sts(  ippiCannyGetSize(roiSize, &iTmpBufSizeCanny) )

        /* Find maximum buffer size */
        iTmpBufSize = (iTmpBufSizeSobV > iTmpBufSizeSobH) ? iTmpBufSizeSobV : iTmpBufSizeSobH;
        iTmpBufSize = (iTmpBufSize > iTmpBufSizeCanny) ? iTmpBufSize : iTmpBufSizeCanny;
        buffer = ippsMalloc_8u(iTmpBufSize);

        check_sts(  status = ippiFilterSobelNegVertBorder_8u16s_C1R(pSrc, srcStep, buffer_dx, dxStep, roiSize, ippMskSize3x3, ippBorderRepl, BORDER_VAL, buffer) )

        check_sts(  status = ippiFilterSobelHorizBorder_8u16s_C1R(pSrc, srcStep, buffer_dy, dyStep, roiSize, ippMskSize3x3, ippBorderRepl, BORDER_VAL, buffer) )

        check_sts(  status = ippiCanny_16s8u_C1R(buffer_dx, dxStep, buffer_dy, dyStep, pDst, dstStep, roiSize, THRESH_LOW, THRESH_HIGHT, buffer) )
    }

EXIT_MAIN
    ippsFree(buffer);
    ippiFree(buffer_dx);
    ippiFree(buffer_dy);
    ippiFree(pSrc);
    ippiFree(pDst);
    printf("Exit status %d (%s)\n", (int)status, ippGetStatusString(status));
    return (int)status;
}

Parent topic: Canny Edge Detector

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Intel® Integrated Performance Primitives Developer Guide and Reference

Canny

Syntax

Include Files

Domain Dependencies

Parameters

Description

Return Values

Example