Developer Reference

  • 2020
  • 10/21/2020
  • Public Content
Contents

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 2015-2020 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; }

Product and Performance Information

1

Intel's compilers may or may not optimize to the same degree for non-Intel microprocessors for optimizations that are not unique to Intel microprocessors. These optimizations include SSE2, SSE3, and SSSE3 instruction sets and other optimizations. Intel does not guarantee the availability, functionality, or effectiveness of any optimization on microprocessors not manufactured by Intel. Microprocessor-dependent optimizations in this product are intended for use with Intel microprocessors. Certain optimizations not specific to Intel microarchitecture are reserved for Intel microprocessors. Please refer to the applicable product User and Reference Guides for more information regarding the specific instruction sets covered by this notice.

Notice revision #20110804