HoughProbLine

Intel® Integrated Performance Primitives Developer Guide and Reference

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ID 790148

Date 11/07/2023

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HoughProbLine

Detects lines in the source image using the probabilistic Hough transform.

Syntax

IppStatus ippiHoughProbLine_8u32f_C1R(const Ipp8u* pSrc, int srcStep, IppiSize roiSize, int threshold, int lineLength, int lineGap, IppiPoint* pLine, int maxLineCount, int* pLineCount, Ipp8u* pBuffer, const IppiHoughProbSpec* pSpec);

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 ROI.
srcStep: Distance, in bytes, between the starting points of consecutive lines in the source image.
roiSize: Size of the source image ROI in pixels.
threshold: Minimum number of points that are required to detect the line.
lineLength: Minimum length of the line.
lineGap: Maximum length of the gap between lines.
pLine: Pointer to the detected line: pLine[2*n] indicates beginning of the line, pLine[2*n+1] indicates end of the line.
pLineCount: Number of detected lines.
maxLineCount: Number of elements in the destination buffer.
pBuffer: Pointer to the working buffer.
pSpec: Pointer to the specification structure.

Description

This function operates with ROI.

This function detects line segments of the binary pSrc image using the probabilistic Hough transform. Before using this function, compute the size of the working buffer and specification structure using the ippiHoughProbGetSize function and initialize the structure using the ippiHoughProbLineInit function.

This function implements the probabilistic Hough transform algorithm for line detection, described in [Matas00].

Return Values

ippStsNoErr	Indicates no error.
ippStsNullPtrErr	Indicates an error if one of the specified pointers is `NULL`.
ippStsSizeErr	Indicates an error condition if roiSize has a field with zero or negative value; or if maxLineCount is less than or equal to 0.
ippStsStepErr	Indicates an error condition if srcStep has an illegal value.
ippStsBadArgErr	Indicates an error condition if threshold is less than or equal to 0.
ippStsDstSizeLessExpected	Indicates a warning if number of the detected lines is greater than the size of the destination buffer maxLineCount.

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 detecting lines in the source image using
// the probabilistic Hough transform using Intel(R) Integrated Primitives (Intel(R) IPP) functions:
//     ippiHoughProbLineGetSize_8u_C1R
//     ippiHoughProbLineInit_8u32f_C1R
//     ippiHoughProbLine_8u32f_C1R


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

#define WIDTH  800  /* image width  */
#define HEIGHT 600  /* image height */

/* 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)
{
    int i = 0;
    IppStatus status = ippStsNoErr;
    Ipp8u* pSrc = NULL;    /* Pointers to source images */
    int srcStep = 0;       /* Steps, in bytes, through the source images */
    IppiSize roiSize = { WIDTH, HEIGHT };    /* Size of source ROI in pixels */
    int bufferSize = 0, specSize = 0;/* Size of the working buffer and spec structure */
    Ipp8u *pBuffer = NULL;
    IppiHoughProbSpec*  pSpec = NULL;
    IppiPoint pLineP[128]; /* Pointer to output array of detected lines */
    int threshold = 20, lineLength = 40, ineGap = 4, maxLineCount = 128;
    IppPointPolar delta = { 1, (Ipp32f)IPP_PI / 180.f / 3.f }; /* Step of discretization */
    int  lineCount = 0; /* Number of detected lines. */

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

    check_sts( status = ippiSet_8u_C1R(0, pSrc, srcStep, roiSize) ) /* Zero image */

    for (i = 0; i<70; i++) {     /* Draw line (100,100)-(170,170) */
        pSrc[(i + 100)*srcStep + i + 100] = 255;
    }

    /* Compute the size of the working buffer and spec structure */
    check_sts( status = ippiHoughProbLineGetSize_8u_C1R(roiSize, delta, &specSize, &bufferSize) )

    pBuffer = (Ipp8u*)ippsMalloc_8u(bufferSize);
    pSpec = (IppiHoughProbSpec*)ippsMalloc_8u(specSize);

    /* Initialize the specification structure */
    check_sts( status = ippiHoughProbLineInit_8u32f_C1R(roiSize, delta, ippAlgHintNone, pSpec) )

    /* Detect lines in the source image using the probabilistic Hough transform. */
    check_sts( status = ippiHoughProbLine_8u32f_C1R(pSrc, srcStep, roiSize, threshold, lineLength, ineGap, pLineP, maxLineCount, &lineCount, pBuffer, pSpec) )

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

Parent topic: Hough Transform

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Intel® Integrated Performance Primitives Developer Guide and Reference

HoughProbLine

Syntax

Include Files

Domain Dependencies

Parameters

Description

Return Values

Example

See Also