Intel® Integrated Performance Primitives (Intel® IPP) Developer Guide and Reference

ID 790148
Date 3/22/2024
Public

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Document Table of Contents

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

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* Copyright 2015 Intel Corporation.
*
*
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// A simple example of detecting lines in the source image using
// the probabilistic Hough transform using Intel(R) Integrated Performance 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;
}

See Also