CannyBorder

Syntax

Include Files

ippcv.h

Domain Dependencies

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

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

Parameters

pSrc

Pointer to the source image.

srcStep

Distance, in bytes, between the starting points of consecutive lines in the source image.

pDst

Pointer to the destination image.

dstStep

Distance, in bytes, between the starting points of consecutive lines in the destination image.

roiSize

Size of the source image ROI in pixels.

filterType

Type of the filter to be applied. Possible values are ippFilterSobel and ippFilterScharr.

mask

The size of the mask. Possible values are ippMskSize3x3 and ippMskSize5x5 for ippFilterSobel, and ippMskSize3x3 for ippFilterScharr.

borderType

Type of border. Possible values are:

ippBorderConst	Values of all border pixels are set to constant.
ippBorderRepl	Border is replicated from the edge pixels.
ippBorderInMem	Border is obtained from the source image pixels in memory.

Mixed borders are also supported. They can be obtained by the bitwise operation OR between ippBorderRepl and ippBorderInMemTop, ippBorderInMemBottom, ippBorderInMemLeft, ippBorderInMemRight.

borderValue

Constant value to assign to pixels of the constant border. This parameter is applicable only to the ippBorderConst border type.

lowThresh

Lower threshold for edges detection.

highThresh

Upper threshold for edges detection.

norm

Normalization mode. Possible values are ippNormL1 and ippNormL2.

pBuffer

Pointer to the pre-allocated temporary buffer. To calculate the size of the temporary buffer, use the CannyBorderGetSize function.

Description

This function operates with ROI (see Regions of Interest in Intel IPP). This function finds edges in the ROI of the source image with the user-defined border types using the Canny edge detector algorithm. The output image is stored in pDst.

Before using this function, compute the size of the temporary work buffer using the CannyBorderGetSize function.

Return Values

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 edge detection algorithm implemented with Intel® Integrated Performance Primitives (Intel® IPP) functions:
//     ippiCannyBorderGetSize
//     ippiCannyBorder_8u_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® IPP function returned status different from ippStsNoErr */

/* Results of ippMalloc() are not validated because Intel® 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 */
    Ipp8u *pBuffer = NULL;      /* Pointer to the work buffer */
    int iTmpBufSize = 0;        /* Common work buffer size */
    IppiDifferentialKernel filterType = ippFilterScharr;

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

    /* Start Edge Detection algorithm */
    check_sts( status = ippiCannyBorderGetSize(roiSize, filterType, ippMskSize3x3, ipp8u, &iTmpBufSize) )

    pBuffer = ippsMalloc_8u(iTmpBufSize);

    check_sts( status = ippiCannyBorder_8u_C1R(pSrc, srcStep, pDst, dstStep, roiSize,
        filterType, ippMskSize3x3, ippBorderRepl, BORDER_VAL, THRESH_LOW, THRESH_HIGHT, ippNormL2, pBuffer) )

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