Otsu Threshold computation

Computation of the binary threshold on one image, using Otsu method. More...

Functions
IPSDKIPLBINARIZATION_API ipReal64	ipsdk::imaproc::bin::otsuThreshold (const ipsdk::image::ImageConstPtr &pInImg)
	wrapper function for computing the otsu threshold on one image. 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::otsuThreshold (const ipsdk::image::ImageConstPtr &pInImg, const ipsdk::imaproc::attr::HistogramDataPtr &pHistogram)
	wrapper function for computing the otsu threshold on one image, using the histogram provided as argument More...

Detailed Description

Computation of the binary threshold on one image, using Otsu method.

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.

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

Global Rule description

Global rule description for algorithm :
ipsdk::processor::none ()

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
    otsuThresholdValue = bin.otsuThreshold(inImg)

Example of C++ code :

Example informations

Associated library

IPSDKIPLBinarization

Header file

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

Code Example

        // open input image
        ImageGeometryPtr pInputImageGeometry = geometry2d(inType, sizeX, sizeY);
        ImagePtr pInImg = loadRawImageFile(inPath, *pInputImageGeometry);

        // Sample calculating automatically the histogram
        // ----------------------------------------------

        // compute otsu threshold associated to input image
        ipReal64 outThresholdValue = otsuThreshold(pInImg);

        // Sample with the histogram as input parameter
        // ----------------------------------------------

        // Set the histogram parameters
        const ipReal64 min = 50.;
        const ipReal64 max = 250.;
        const ipReal64 fBinWidth = 2.;
        HistoMsrParamsPtr pHistoPrms = createHistoMsrParamsWithBinWidth(min, max, fBinWidth);

        // Compute the histogram
        HistogramDataPtr pHistogramData = histogramMsr(pInImg, pHistoPrms);

        // compute otsu threshold associated to input image
        ipReal64 outThresholdValue_manualHisto = otsuThreshold(pInImg, pHistogramData);

See also

OtsuThresholdLvl1

Function Documentation

otsuThreshold() [1/2]

IPSDKIPLBINARIZATION_API ipReal64 ipsdk::imaproc::bin::otsuThreshold

(

const ipsdk::image::ImageConstPtr &

pInImg

)

wrapper function for computing the otsu threshold on one image. In this version of the function, the histogram of the image is automatically computed, with a bin width of 1.0

Note

the binarized image is not computed

Exceptions

ipsdk::processor::IPSDKBaseProcessingException

on failure

otsuThreshold() [2/2]

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

wrapper function for computing the otsu threshold on one image, using the histogram provided as argument

Note

the binarized image is not computed

Exceptions

ipsdk::processor::IPSDKBaseProcessingException

on failure