computes the accumulator matrix used by the Hough circles detector ("gradient" method) More...

IPSDKIPLFEATUREDETECTION_API image::ImagePtr	ipsdk::imaproc::fd::houghCircles2dImg (const image::ImageConstPtr &pInGxImg, const image::ImageConstPtr &pInGyImg, const ipsdk::imaproc::attr::HoughCirclesRadiusRangeConstPtr &pRadiusRange)
	wrapper function for detects circles in images of gradient using Hough algorithm More...

IPSDKIPLFEATUREDETECTION_API void	ipsdk::imaproc::fd::houghCircles2dImg (const image::ImageConstPtr &pInGxImg, const image::ImageConstPtr &pInGyImg, const ipsdk::imaproc::attr::HoughCirclesRadiusRangeConstPtr &pRadiusRange, const ipsdk::imaproc::attr::eCircleIntensityType &eCircleIntensityType, const ipReal64 maxAngleWithGradDir, const ipUInt32 nbMaxPtsPerCircle, const image::ImagePtr &pOutImg)
	wrapper function for detects circles in images of gradient using Hough algorithm More...

Detailed Description

computes the accumulator matrix used by the Hough circles detector ("gradient" method)

This algorithm computes, from the 2 gradient images (respectively along x and y axis) of the same grey levels 2d image, the accumulator matrix used to detect circles in an image, using Hough algorithm ("gradient" method).

See Hough circles detection for more information.

Below is an example of image returned by the algorithm on gradient images computed from an image of coins. We can see that positions of high local maxima in accumulation matrix correspond to positions of centers of circles in the original image:

Attributes description

Attribute description for algorithm :

Name	ToolTip	Default Initializer
ipsdk::imaproc::attr::InGxGreyImg2d	[Input] 2d grey levels image of gradient computed along x-axis	X
ipsdk::imaproc::attr::InGyGreyImg2d	[Input] 2d grey levels image of gradient computed along y-axis	X
ipsdk::imaproc::attr::InOptCircleIntensityType	[Input Optional] circle intensity type for detection algorithms	X
ipsdk::imaproc::attr::InOptMaxAngleWithGradDir	[Input Optional] maximum angle with gradient direction, in radians	X
ipsdk::imaproc::attr::InOptNbMaxPtsPerCircle	[Input Optional] maximum number of points per circle	X
ipsdk::imaproc::attr::InOptHoughCirclesRadiusRange	[Input Optional] range of radius of circles to detect using Hough circles algorithm	X
ipsdk::imaproc::attr::OutRealImg	[Output] image for processing operation (data contained in image buffer are reals)	ipsdk::imaproc::duplicateInOut (_pOutRealImg, _pInGxGreyImg2d, ipsdk::image::eImageBufferType::eIBT_Real32)

Global Rule description

Global rule description for algorithm :
ipsdk::imaproc::matchSizeAndType (_pInGxGreyImg2d,_pInGyGreyImg2d) &&
ipsdk::imaproc::matchSize (_pInGxGreyImg2d,_pOutRealImg) && ipsdk::imaproc::matchSize<ipsdk::imaproc::attr::HoughCirclesRadiusRange::MaxRadius>(ipsdk::imaproc::eMatchImageSizeType::eMIST_2d,ipsdk::imaproc::eMatchImageSizeScale::eMISS_HalfSize,_pInGxGreyImg2d,_pInOptHoughCirclesRadiusRange)

Example of Python code :

Example imports

import PyIPSDK
import PyIPSDK.IPSDKIPLFeatureDetection as fd
import PyIPSDK.IPSDKIPLFiltering as filter

Code Example

    # opening of input image
    inImg = PyIPSDK.loadTiffImageFile(inputImgPath)
    
    # associated gradient images computation
    gxImg,  gyImg = filter.gaussianGradient2dImg(inImg,  1.0)
    
    # radius range detection definition
    radiusRange = PyIPSDK.createHoughCirclesRadiusRange(15,  20)
    
    # hough circle detection computation
    outImg = fd.houghCircles2dImg(gxImg,  gyImg,  radiusRange)

Example of C++ code :

Example informations

Associated library

IPSDKIPLFeatureDetection

Header file

#include <IPSDKIPL/IPSDKIPLFeatureDetection/Processor/HoughCircles2dImg/HoughCircles2dImg.h>

Code Example

#include <IPSDKImageFile/Tiff/TiffImageFileUtils.h>
#include <IPSDKIPL/IPSDKIPLFeatureDetection/Processor/HoughCircles2dImg/HoughCircles2dImg.h>
// function returning the accumulation image used by Hough circle detector
// ("gradient" method) applied on an input image loaded from a given file to 
// detect circles of radii belonging to a given range
ImagePtr
computeHoughCircles2dImage(
    const std::string& inImgFilePath,
    ipUInt64 nMinRadius,
    ipUInt64 nMaxRadius)
{
    // load input image from file specified by the user
    ipsdk::image::ImagePtr pInImg =
        ipsdk::image::file::loadTiffImageFile(inImgFilePath);
    // compute gradient images, in x and y
    GradientXYImg gxyImg =
        gaussianGradient2dImg(pInImg, 1.0f, 1.0f, createGaussianCoverage(0.997f, 2));
    ImagePtr pInGxImg = gxyImg._pXGradImg;
    ImagePtr pInGyImg = gxyImg._pYGradImg;
    // apply Hough circles detection on gradient images
    ImagePtr pAccumulationImg =
        ipsdk::imaproc::fd::houghCircles2dImg(
            pInGxImg,
            pInGyImg,
            ipsdk::imaproc::attr::createHoughCirclesRadiusRange(nMinRadius, nMaxRadius));
    // return the accumulation image
    return pAccumulationImg;
}

See also: HoughCircles2dImgLvl1; HoughCircles2dImgLvl2; HoughCircles2dImgLvl3

Function Documentation

◆ houghCircles2dImg() [1/2]

IPSDKIPLFEATUREDETECTION_API image::ImagePtr ipsdk::imaproc::fd::houghCircles2dImg	(	const image::ImageConstPtr &	pInGxImg,
		const image::ImageConstPtr &	pInGyImg,
		const ipsdk::imaproc::attr::HoughCirclesRadiusRangeConstPtr &	pRadiusRange
	)

wrapper function for detects circles in images of gradient using Hough algorithm

Exceptions

ipsdk::processor::IPSDKBaseProcessingException on failure

◆ houghCircles2dImg() [2/2]

IPSDKIPLFEATUREDETECTION_API void ipsdk::imaproc::fd::houghCircles2dImg	(	const image::ImageConstPtr &	pInGxImg,
		const image::ImageConstPtr &	pInGyImg,
		const ipsdk::imaproc::attr::HoughCirclesRadiusRangeConstPtr &	pRadiusRange,
		const ipsdk::imaproc::attr::eCircleIntensityType &	eCircleIntensityType,
		const ipReal64	maxAngleWithGradDir,
		const ipUInt32	nbMaxPtsPerCircle,
		const image::ImagePtr &	pOutImg
	)

wrapper function for detects circles in images of gradient using Hough algorithm

Exceptions

ipsdk::processor::IPSDKBaseProcessingException on failure