Compute the Otsu threshold of an input image, and binarize the image using this threshold. More...

IPSDKIPLBINARIZATION_API OtsuResult	ipsdk::imaproc::bin::otsuThresholdImg (const ipsdk::image::ImageConstPtr &pInImg)
	wrapper function for binarization on one image using Otsu's method. In this version of the function, the histogram of the image is automatically computed, with a bin width of 1.0 More...

IPSDKIPLBINARIZATION_API ipReal64	ipsdk::imaproc::bin::otsuThresholdImg (const ipsdk::image::ImageConstPtr &pInImg, const ipsdk::image::ImagePtr &pOutBinImg)
	wrapper function for binarization on one image using Otsu's method. In this version of the function, the histogram of the image is automatically computed, with a bin width of 1.0 More...

IPSDKIPLBINARIZATION_API OtsuResult	ipsdk::imaproc::bin::otsuThresholdImg (const ipsdk::image::ImageConstPtr &pInImg, const ipsdk::imaproc::attr::HistogramDataPtr &pHistogram)
	wrapper function for binarization on one image using Otsu's method. histogram used to compute the Otsu's threshold is provided as argument of the function More...

IPSDKIPLBINARIZATION_API ipReal64	ipsdk::imaproc::bin::otsuThresholdImg (const ipsdk::image::ImageConstPtr &pInImg, const ipsdk::imaproc::attr::HistogramDataPtr &pHistogram, const ipsdk::image::ImagePtr &pOutBinImg)
	wrapper function for binarization on one image using Otsu's method. histogram used to compute the Otsu's threshold is provided as argument of the function More...

Detailed Description

Compute the Otsu threshold of an input image, and binarize the image using this threshold.

Otsu's method is used to automatically perform the binarization of an input image. It assumes that the image is bi-modal (pixel intensities can be distinguished in 2 classes: background pixels and foreground pixels). It then calculates the optimal threshold that separates these 2 classes, by minimizing their intra-class variance. In this implementation, the alternate method (maximizing the inter-classes variance) is used. It has the advantage to be faster than the first method.

See also: http://en.wikipedia.org/w/index.php?title=Otsu%27s_method&oldid=617320940 for more details.

On output, binarized image values are given by:

$OutBinImg[i] = \begin{cases} 1, & \text{if } InImg[i] \geq OtsuThreshold \\ 0, & \text{otherwise} \end{cases}$

with $OtsuThreshold$ the threshold computed from Otsu's method.

Input and output images must have same size and buffer type.

Here is an example of automatic otsu image thresholding applied to a 8-bits grey level image (on ouput, computed threshold equals 118) :

Attributes description

Attribute description for algorithm :

Name	ToolTip	Default Initializer
ipsdk::imaproc::attr::InImg	[Input] image for processing operation	X
ipsdk::imaproc::attr::InOutOptHistogram	[InOut Optional] histogram properties	X
ipsdk::imaproc::attr::OutThreshold	[Output] threshold value for image binarization	X
ipsdk::imaproc::attr::OutBinImg	[Output] binary image for processing operation	ipsdk::imaproc::duplicateInOut (_pOutBinImg, _pInImg, image::eImageBufferType::eIBT_Binary)

Global Rule description

Global rule description for algorithm :
ipsdk::imaproc::matchSize (_pInImg,_pOutBinImg)

Example of Python code :

Example imports

import PyIPSDK

import PyIPSDK.IPSDKIPLBinarization as bin

Code Example

    # opening of input images
    inImg = PyIPSDK.loadTiffImageFile(inputImgPath)    
    
    # otsu threshold computation
    outImg,  otsuThresholdValue = bin.otsuThresholdImg(inImg)

Example of C++ code :

Example informations

Associated library

IPSDKIPLBinarization

Header file

#include <IPSDKIPL/IPSDKIPLBinarization/Processor/OtsuThresholdImg/OtsuThresholdImg.h>

Code Example

        // open input image
        ImageGeometryPtr pInputImageGeometry = geometry2d(inType, sizeX, sizeY);
        ImagePtr pInImg = loadRawImageFile(inPath, *pInputImageGeometry);
        // Sample with a generated output image
        // ------------------------------------
        // compute thresholded output image
        OtsuResult otsuResult = otsuThresholdImg(pInImg);
        // Sample with a provided output image
        // -----------------------------------
        // create output image
        ImageGeometryPtr pOutputImageGeometry = geometry2d(eImageBufferType::eIBT_Binary, sizeX, sizeY);
        boost::shared_ptr<MemoryImage> pOutImg(boost::make_shared<MemoryImage>());
        pOutImg->init(*pOutputImageGeometry);
        // compute thresholded output image
        ipReal64 fOutThreshold = otsuThresholdImg(pInImg, pOutImg);

See also: OtsuThresholdImgLvl1

Function Documentation

◆ otsuThresholdImg() [1/4]

IPSDKIPLBINARIZATION_API OtsuResult ipsdk::imaproc::bin::otsuThresholdImg ( const ipsdk::image::ImageConstPtr & pInImg )

wrapper function for binarization on one image using Otsu's method. In this version of the function, the histogram of the image is automatically computed, with a bin width of 1.0

Exceptions

ipsdk::processor::IPSDKBaseProcessingException on failure

◆ otsuThresholdImg() [2/4]

IPSDKIPLBINARIZATION_API OtsuResult ipsdk::imaproc::bin::otsuThresholdImg	(	const ipsdk::image::ImageConstPtr &	pInImg,
		const ipsdk::imaproc::attr::HistogramDataPtr &	pHistogram
	)

wrapper function for binarization on one image using Otsu's method. histogram used to compute the Otsu's threshold is provided as argument of the function

Exceptions

ipsdk::processor::IPSDKBaseProcessingException on failure

◆ otsuThresholdImg() [3/4]

IPSDKIPLBINARIZATION_API ipReal64 ipsdk::imaproc::bin::otsuThresholdImg	(	const ipsdk::image::ImageConstPtr &	pInImg,
		const ipsdk::image::ImagePtr &	pOutBinImg
	)

wrapper function for binarization on one image using Otsu's method. In this version of the function, the histogram of the image is automatically computed, with a bin width of 1.0

Exceptions

ipsdk::processor::IPSDKBaseProcessingException on failure

◆ otsuThresholdImg() [4/4]

IPSDKIPLBINARIZATION_API ipReal64 ipsdk::imaproc::bin::otsuThresholdImg	(	const ipsdk::image::ImageConstPtr &	pInImg,
		const ipsdk::imaproc::attr::HistogramDataPtr &	pHistogram,
		const ipsdk::image::ImagePtr &	pOutBinImg
	)

wrapper function for binarization on one image using Otsu's method. histogram used to compute the Otsu's threshold is provided as argument of the function

Exceptions

ipsdk::processor::IPSDKBaseProcessingException on failure