The algorithm assumes that the image contains two classes of pixels following a bi-modal histogram (foreground pixels and background pixels), it then calculates the optimum threshold separating the two classes so that their combined spread is minimal, or equivalently so that their inter-class variance is Otsu. 0 License , respectively. The source code and files included in this project are listed in the project files section, please make sure whether the listed source code meet your needs there. Image thresholding is a simple form of image segmentation. How can I use it in my code? I read about it and I don't understand very well. In global thresholding, we used an arbitrary chosen value as a threshold. May 09, 2016 · 14 Thresholding Matlab Code dimarifii1. math. the pixels that either fall in foreground or For enhancing the performance of the Otsu algorithm further, in this work, an improved median-based Otsu image thresholding algorithm is presented. เนื้อหาในบทนี้ จะเรียนรู้เกี่ยวกับ แบ่งเส้น แบบง่ายๆ (Simple thresholding) ,การแบ่งแบบ Adaptive,การแบ่งแบบ Otsu's In the previous blogs, we discussed various thresholding methods such as Otsu, adaptive, BHT, etc. It is implemented in pure matlab. [ T, EM ] = graythresh(I) also returns the effectiveness metric, EM. OpenCV3 Implementation of Otsu by pure code; OpenCV3 thresholdAlgorithm call Otsu thresholding; Improved version; OpenCV3Function adaptiveThreshold to realize adaptive threshold; two valued graph. Now we need go to each pixel and compute the cumulative histogram for a window of size s*s=2*r+1 $\times$ 2*r +1. We can effectuate \(5\) types of Thresholding operations with this function. import matplotlib. In , the classic Otsu thresholding and static thresholding are applied for object detection using the sector scanning sonar. What I didn't understand was that Otsu, K-Means and Isodata are completely identical for the given inputs. Otsu works by minimizing the spread of background and foreground pixels. Otsu thresholding is an old algorithm that is an adaptive thresholding technique. If you say that the background is dark (black) and the foreground is lighter, then I recommend to use the YUV color space (or any other YXX like YCrCb, etc. • Otsu’smethod (Petrou et al. Then, someone told me about the otsu threshold. Thresholding plays a major role in binarization of images. The following Matlab project contains the source code and Matlab examples used for performs local otsu thresholding on an image, with a user-specified blocksize. Let's say the red range starts at 32 degrees and ends at 33 degrees. First identify the values of the starting and ending thermal values in your image. Abstract: This paper presented an improved image segmentation algorithm based on 2D Otsu, in which two-dimensional histogram was mainly build by gray and neighborhood gray gradient of two tuples, and then calculated the biggest Otsu value of the object area and the background area in image, at last, got the threshold of the image. This pseudo code has nothing to do with Otsu's Method. Check out below example. In the simplest form, the algorithm returns a single intensity threshold that separate pixels into two classes, foreground and background. Thresholding from Java. 2. Sign up An implementation of Otsu's image thresholding algorithm done in C++ for my Computer Vision class at NYU Poly Dec 06, 2012 · The graythresh function uses Otsu's method, which chooses the threshold to minimize the intraclass variance of the black and white pixels. Otsu Thresholding Explained Otsu's thresholding method involves iterating through all the possible threshold values and calculating a measure of spread for the pixel levels each side of the threshold, i. Note: If block size is smaller it can take more time to run and too small block size may not always produce good results. Both grayscale and two value maps are thresholding knowledge. Let’s look at the various threshold types available in OpenCV. Below piece of code compares global thresholding and adaptive thresholding for an image with varying illumination: import cv2 import numpy as np from matplotlib import pyplot as plt img = cv2 . Please try again later. This threshold is determined by minimizing intra-class intensity variance, or equivalently, by maximizing inter-class variance. Then I applied Otsu’s thresholding directly. the pixels that either fall in foreground or background. Lets imagine that you have already converted the image into gray-scale. jar, which can be opened using a ZIP utility Installation: Download Otsu_Thresholding. bw1 = imbinarize(I); imshow(bw1) title( 'Global threshold' ) And here is the binarization using an adaptive threshold. Mar 17, 2014 · my supervisor told me that points you get from your corner detection determine your distance, so it really depends. Using the code. This program show the effect of thresholding. This page describes an algorithm for performing blob detection in monochrome images. I am doing Plant leaf disease detection & classification project. Multi-Otsu Thresholding ¶ The multi-Otsu threshold 1 is a thresholding algorithm that is used to separate the pixels of an input image into several different classes, each one obtained according to the intensity of the gray levels within the image. It uses cv2. This plugin allows the user to segment the current image using any of the 15 thresholding methods from Gabriel Landini's Auto Threshold plugin. please help me. find a suitable thresholding to get the best representation of an object in the image . In order to solve this problem, we present a robust 2D Otsu’s thresholding method in this paper. pyramidal watershed segmentation code source, optimum global thresholding using otsu s method in image processing, ppt on classification of watershed, optimum global thresholding using otsu s method ppton line apply for jubasree in wb, pyramidal watershed segmentation of medical images, improved watershed segmentation algorithm ppt, image segmentation using otsu thresholding matlab code, Mar 28, 2018 · The example code has been updated with the integers cast to floats during the calculation. foreground and background). 7 Otsu threshold on color images. Otsu Thresholding A somewhat technical overview of the Otsu algorithm can be found in section 2 of this paper . The output are four subfigures shown in the same figure: Subfigure 1: The initial "lena" Subfigure 2: Threshold level is one alfa Subfigure 3: Threshold level is two alfa Subfigure 4: Threshold level is three alfa Oct 17, 2014 · % Otsu image thresholding (for image thresholds > 0) % Otsu, N. threshold(image, image, 0, 255, Imgproc. , regions with high homogeneity will have low variance). so i am using some constant threshold value(0. In computer vision and image processing, Otsu's method, named after Nobuyuki Otsu, is used to perform automatic image thresholding. Otsu's method chooses a threshold that minimizes the intraclass variance of the thresholded black and white pixels. Otsu's method is a one-dimensional discrete analog of Fisher's Discriminant Analysis, is related to J Otsu's method chooses a threshold that minimizes the intraclass variance of the thresholded black and white pixels. 3 Histogram Shape-Based Thresholding Methods This category of methods achieves thresholding based on The program is designed for globle image thresholding. GitHub is home to over 40 million developers working together to host and review code, manage projects, and build software together. Otsu method was proposed by Scholar Otsu in 1979. Thus we have used the ability of 32X32 neighborhood processing. Imgproc. The code can be inspected by Otsu method is type of global thresholding in which it depend only gray value of the image. The Otsu’s method chooses the threshold value that minimises the intraclass variance between two classes, the background and foreground. e. Image Thresholding วัตถุประสงค์. It's pretty simple code, but also very useful, so +1 from my side! Liked your threshold comparison study btw, and its amazing conclusion . Hi, I would like to create a multi-level Otsu thresholding routine, but before I try to do it, I wondered if anyone has already done the job? The routine I would like is the same as the 'graythresh' command in Matlab. Otsu's method, named after its inventor Nobuyuki Otsu, is one of the binarization algorithms. Otsu's method is a global thresholding technique. Jul 24, 2016 · As for the name, "Otsu's method" seems to be standard, but "Otsu's Thresholding" is more explicit and sounds better, thanks for the idea, I'll integrate that into the next update. For threshold value, simply pass zero. First, you may convert to gray-scale, but then you have to consider that grayscale still has at least 255 Jul 10, 2014 · OpenCV: Implementation of Threshold by OTSU method Here is a simple example showing implementation of OTSU thresholding in OpenCV. its a really I'm referring to Otsu's thresholding, and saw this from his paper: When he says he's trying to maximize the between class variance of thresholds k* 1 and 2, is it the threshold with maximum value image-processing image-segmentation thresholding Otsu's thresholding algorithm is implemented in the function graythresh(), from the Image Processing Toolbox. The system basically inputs an color image with formats recognizable by the MATLAB, such as JPG, TIF, and PNG. To execute Otsu thresholding with OpenCV it is necessary to pass an additional flag (THRESH_OTSU) to the threshold() function as well as one of the five threshold types explained in the previous section. BoofCV provides several methods for automatically computing global thresholds based on different theories. Otsu's thresholding method involves iterating through all the possible threshold values and calculating a measure of spread for the pixel levels each side of the threshold, i. This method's describes the iterative method to obtain the ideal threshold by Gonzalez and Woods [2002]. . Apr 13, 2017 · Introduction. WINDOW_NORMAL = Enables window to resize. Simply pass 0 as a threshold value, it is omitted anyway. This method involves iterating through all the possible threshold values and calculating a measure of spread for the pixel levels each side of the threshold, i. Moreover, there are many popular thresholding techniques such as Kittler and Illingworth, Kapur , Tsai , Huang , Yen and et al [9]. level is a normalized intensity value that lies in the range [0, 1]. THRESH_OTSU); I have been looking around and I see various recommendations on what to put in for the threshold and max value. repeat this experiment with several images pleasssssssssssse help me before next sunday my regard Aug 20, 2018 · Otsu's thresholding method involves iterating through all the possible threshold values and calculating a measure of spread for the pixel levels each side of the threshold (the pixels that either fall in foreground or background). These are the steps in brief, of this implementation. Contained in Otsu_Thresholding. Another Thresholding technique is Adaptive Thresholding. This is naively equivalent to multiple thresholding where we assign a particular value to the region falling in between the two thresholds. Oct 25, 2017 · Python Program To Apply Otsu Thresholding Using OpenCV. This is typically done in order to separate "object" or foreground pixels from background pixels to aid in image processing. tau. In contrast, Otsu's method avoids having to choose a value and determines it automatically. Otsu method is global selection method, which is widely used because simple and effective [4]. image segmentation using watershed algorithm matlab code, matlab code for image denoising using wavelet thresholding, pyramidal watershed segmentation of medical images, image segmentation using otsu thresholding matlab code, matlab code for image denoising using adaptive wavelet thresholding, ppt on classification of watershed, optimal global shaimaa, you would NOT use Otsu for that. 1, January 1979. C++ Code. Entropy maximizes the entropy between the foreground and background regions. BoofCV provides several algorithms for computing both global and locally adaptive thresholds. EDIT : Jan 27, 2012 · All thresholding classes have an associated calculator class that operates on the histogram to estimate the threshold. , pp. Description: This algorithm is an implementation of the Otsu thresholding technique [otsu79]. … Apr 25, 2012 · OTSU thresolding its true that MATLAB'sgraythresh function is based on that method The OTSU's method considers the threshold value as the valley between two peaks that is one of the foreground pixels and the other of the background pixels Prerequisite: Simple Thresholding using OpenCV. These methods create a histogram then use a heuristic to determine a threshold value. Here is the binarization using a global threshold. $\endgroup$ – user14952 Mar 6 '15 at 10:05 Aug 29, 2017 · Otsu code use for Global Thresholding. www. Last updated on Oct 05, 2019. In this tutorial, we'll be covering thresholding for image and video analysis. 3. They are extracted from open source Python projects. 12 the plugin supports thresholding of 16-bit images. For help but can anyone give me whole matlab code for image binarization by Otsu's thresholding method. Since the Auto Threshold plugin processes the full greyscale space, it can be slow when dealing with 16-bit images. 3. A Java code demo is provided, however, the core algorithm is easily ported to other languages. Documentation and code by the Insight Software Consortium is licensed under a Creative Commons Attribution 3. In this blog, we will learn how to segment out a particular region or color from an image. il How to use the OTSU Threshold in opencv? I was using a fixed threshold but turns out that it's not so good for me. The Otsu method requires A Review on Otsu Image Segmentation Algorithm Jun 23, 2014 · Fig. I'm learning about image processing and trying to figure out basics. Consider an image with only two distinct image values (bimodal image), where the histogram would only consist of two peaks. Then the algorithm finds the optimal threshold value and returns us as the second output, retVal. Compute global image threshold for histogram using Otsu’s method. imread ( 'dave. Otsu's Binarization . THRESH_BINARY+Imgproc. . We will explain them in the following subsections. otsu threshold t is the central idea of the goal with the background class of variance between the two biggest. medianBlur ( img , 5 ) ret , th1 = cv2 . This paper proves that the objective function of Otsu method is equivalent to that of K-means method in multilevel thresholding . java; Concepts: Segmentation; Thresholding; Relevant Videos: New Algorithms in v0. Learn more about otsu stacked, thresholding Image Processing Toolbox I tried this code but it finds the threshold Sep 18, 2013 · First of all, otsu threshold was proposed by Nobuyuki otsu in their paper. One of the most well-known thresholding methods is Otsu’s method: Otsu's method chooses a threshold that minimizes the intraclass variance of the thresholded black and white pixels. jpg' , 0 ) img = cv2 . A good threshold would be in the middle of those two values. To do so one have two options. It is a way to create a binary image from a grayscale or full-color image. Note: OTSU threshold available in OpenCV via the function threshold() and by using the pre-defined operand THRESH_OTSU Otsu¶. More information about each of the methods is available as comments in the source code. It uses the histogram of the image for threshold searching process. g. 1. #cv2. [T SM]=graythresh(input gray image); Where T=Threshold>output from following code function otsuthresh SM=Separability Measure Source: Gonzalez Book (Image Processing+Matlab) Otsu (default) Implements Otsu’s method as described in Nobuyuki Otsu (1979). Image Binarization is an important and effectual area of Global thresholding is extremely fast, but it can be unclear what a good threshold is. com> Description Algorithms for automatically finding appropriate thresholds for numerical data, with special functions for thresholding images. here’s a link to the code that generates Thresholding functions have a trivial interface: they take an image and return a value. If we pass the original image to the function it will blend the segment color code with the original image, so the segmentation will be clearly visible. From version 1. 7. THRESH_OTSU(). It is quick and effective in many situations. jar to the plugins folder, or subfolder, restart ImageJ, and there will be a new Plugins/Filters/Otsu Thresholding command. In Adaptive thresholding, the threshold value is calculated for smaller regions with different threshold values for different regions with respect to the change in lighting. You can use thresh as an input argument to imquantize to convert image A into an image with N + 1 discrete levels. Provides the Blob Detection. Let's say I do it manually using Fiji and it yeields "Result-image Matlab code for image binarization by Otsu's Learn more about otsu, threshold Image Processing Toolbox Otsu’s method is a classic thresholding approach in image segmentation. 9. Thresholding gray scale images is one of the most basic ways to segment an image. You need to do it "manually". This post will talk about the implementation of the otsu threshold of openCV2. com $\begingroup$ i want to retain the original values of all the pixels whose value lies above the threshold. Click here to download the full example code. That includes the blob in this case. The algorithm searches for the threshold that minimizes the intra-class variance, defined as a weighted sum of variances of the two classes. In the previous blogs, we discussed various thresholding methods such as Otsu, adaptive, BHT, etc. It helped me in selecting a proper auto thresholding technique. pyplot as plt. Given an image histogram hist finds the optimal threshold value level for conversion to a binary image with im2bw. ostu thresholding Search and download ostu thresholding open source project / source codes from CodeForge. threshold() function with an extra flag, cv2. 256 brightness levels of grayscale images obtained through an appropriate threshold can still reflect the image binary image of global and local features. Otsu method is one of the most successful methods for image thresholding. Otsu's method is named for Nobuyuki Otsu, who published it in IEEE Transactions on Systems, Man, and Cybernetics, vol. "A threshold selection method from gray-level histograms", IEEE Trans. The aim is to find the threshold value where the sum of foreground and background spreads is at its minimum. To illustrate how these thresholding processes work, let's consider that we have a source image with pixels with intensity values \(src(x,y)\). You can vote up the examples you like or vote down the ones you don't like. $\endgroup$ – mark May 15 '12 at 19:52 $\begingroup$ Matlab Source code for Otsu binarization with value preservation. Oct 16, 2012 · How to apply Otsu method to a stacked images. Dec 06, 2012 · The graythresh function uses Otsu's method, which chooses the threshold to minimize the intraclass variance of the black and white pixels. In Simple Thresholding, a global value of threshold was used which remained constant throughout. 0 Unported License and Apache 2. Figure 2: Thresholded images. The local set is a circular ROI and the central pixel is tested against the Otsu threshold found for that region. Following post will introduce the basic idea of otsu threshold based on the text book Digital image processing 3rd, this could help us understand what are the codes trying to do, I would not try to explain the details of otsu threshold becaus The following are code examples for showing how to use cv2. level = graythresh(I) computes a global threshold (level) that can be used to convert an intensity image to a binary image with im2bw. First I applied global thresholding for a value of 127. But thershold value for some type of leaves could not detect the diseased part correctly. 5 Maintainer Rory Nolan <rorynoolan@gmail. Equivalently, this threshold minimizes the intra-class variance. Sign in to answer this question. Dec 30, 2014 · Thank you. Implements a local version of Otsu's global threshold clustering. Loading Unsubscribe from dimarifii1? Segmentation using Threshold value- Adaptive and Otsu's Method - Duration: 5:05. Otsu threshold Previously, in my post about Canny edge detector , we had seen that one of the required steps for obtaining perfectly thinned edges was thresholding , in the source code example for that post I've used an arbitrary good enough value for the thersholds. Oct 31, 2019 · Otsu's thresholding method [1] is useful to automatically perform clustering-based image thresholding. , "A Threshold Selection Method from Gray-Level Histograms," IEEE Transactions on Systems, Man, and Cybernetics, Vol. Thanks MJW and Eli for all the advice and the time you put into this. WINDOW_AUTOSIZE = Default flag. Input image is a noisy image. Error Our Webroot Geek Squad Agents provide repair, installation and setup services on all kinds of tech at more than 1,100 Best Buy stores – including computer & tablet repair, setup and support, TV & home theater repair, car stereo & GPS installation, cell phone repair and home appliance repair. Background In image processing, Otsu’s thresholding method (1979) is used for automatic binarization level decision, based on the shape of the histogram. The MultiThresholder is macro recordable. Image Thresholding Matlab Codes. Pseudo code is an example of K-mean method not Otsu's Pseudo-code now reflects what I think is Otsu's algorithm. 9 (1): 62-66. now select another object and find the best thresholding for it. In essence, the Auto Threshold plugin, with the correct settings, can reproduce the results of the applet, but not the way round. The thresher function calculates the Otsu's threshold for that 32X32 image and returns a 32X32 binary image calculated with threshold value calculated for that block. Sys. from skimage import use a thresholding program (or write your own ) and see an image at many thresholding levels . A bimodal image (two distinct image values) is considered. ac. The graythresh function uses Otsu's method, which chooses the threshold to minimize the intraclass variance of the black and white pixels. Sign in to comment. thresh = multithresh(A,N) returns thresh a 1-by-N vector containing N threshold values using Otsu’s method. The algorithm assumes that the image to be thresholded contains two classes of pixels (e. The algorithm assumes that the image contains two classes of pixels following a bi-modal histogram (foreground pixels and background pixels), it then calculates the optimum threshold separating the two classes so that their combined spread is minimal, or Otsu Thresholding¶ ITK has a number of histogram based automatic thresholding filters including Huang, MaximumEntropy, Triangle, and the popular Otsu’s method. , Man. SMC-9, no. The global threshold T can be used with imbinarize to convert a grayscale image to a binary image. 6). foreground and background) Jul 21, 2018 · It is very easy to implement Otsu's thresholding in Python without using OpenCV and MATLAB. threshold ( img , 127 , 255 , cv2 . The same paper additionally proposes a modified version of the Otsu algorithm in section 3 that it asserts is less computationally expensive than the traditional Otsu algorithm. In that i am using otsu method to calculate threshold value for all leaves. Jul 20, 2009 · Otsu thresholding is a simple yet effective global automatic thresholding method for binarizing grayscale images such as foregrounds and backgrounds. The two value graph is a special gray map, that is, each pixel is white (0) or black (255). Thresholding functions have a trivial interface: they take an image and return a value. The function createSegmentDisplay creates a displayable image with assigning different colors to different segments. This example illustrates automatic Otsu thresholding. In Otsu Thresholding, a value of the threshold isn’t chosen but is determined automatically. While the two-dimensional (2D) Otsu’s method performs better than the original one in segmenting images corrupted by noise, it is sensitive to Salt&Pepper noise. Here is what the pseudo code looks like # Simple threshold function pseudo code if src(x,y) > thresh dst(x,y) = maxValue else dst(x,y) = 0 More generally, there are many types of thresholding based on different threshold rules applied to src ( x , y ) to get dst ( x , y ). Performs LOCAL Otsu thresholding on an image; user can specify blocksize. 17,0. Example Code: ExampleThresholding. Then compute the Otsu's threshold value associated with each pixel window. Comments, Conclusions & Further Work Histogram-based approaches to estimating thresholds are very useful, but also can be surprisingly sensitive to changes in image characteristics. Mar 29, 2017 · Otsu’s Method for Image Segmentation. OpenCV offers the function cv::threshold to perform thresholding operations. Otsu binarization automatically calculates a threshold value from image histogram for a bimodal image. If your image sizes are different (larger), you might want to either change some of the parameters of the code or resize the images roughly to the sizes used here. The algorithm assumes that the distribution of image pixel intensities follows a bi-modal histogram, and separates those pixels into two classes (e. I can do a standard Binary Threshold so I'm assuming it's something specific with Otsu's method that I've misunderstood. This technique is very important in the analysis of images, especially in cases in which you want to apply a threshold in the thresholding techniques in an efficient manner. At this time, researchers had already explored a variety of ways to choose a threshold automatically by examining the histogram of image pixel values. And it outputs a color thresholded image. Note that for your image having local size that doesn't include an object completely misses the point of Otsu's and will pick-up "noise". --Tomash 22:10, 16 February 2008 (UTC) Otsu thresholding. 28 IDX = OTSU(I,N) segments the image I into N classes by means of Otsu's N-thresholding method. For example, Shape–Sezan and Cluster–Otsu, refer, re-spectively, to the shape-based thresholding method intro-duced in a paper by Sezan and to the clustering-based thresholding method first proposed by Otsu. Otsu's thresholding method [1] is useful to automatically perform clustering-based image thresholding. Welcome to another OpenCV tutorial. Otsu’s method 2 calculates an “optimal” threshold (marked by a red line in the histogram below) by maximizing the variance between two classes of pixels, which are separated by the threshold. The idea of thresholding is to further-simplify visual data for analysis. Hey everyone I have an 8-bit image, and I'm trying to threshold using Fiji's Image -> Adjust -> Threshold. , Cyber. otsu ( photo ) print ( T_otsu ) imshow ( photo > T_otsu ) show () otsu thresholding python (3) . Jul 14, 2017 · This feature is not available right now. Multi-Otsu calculates several thresholds, determined by the number of desired classes. One of the most well-known thresholding methods is Otsu’s method: T_otsu = mahotas . The Otsu thresholder algorithm can be applied on color images as well. The Otsu Threshold is one of [binarization algorithms], named after its inventor Nobuyuki Otsu. Function otsu_method is copy-pasted code, for this reason I'm not crystal clear about variables or conditions. -Otsu’smethod selects the threshold by minimizing the within-class variance of the twogroups of pixels separated by the thresholding operator. If you are in a hurry, jump to the code. Later I filtered it with a 5x5 gaussian kernel to remove the noise, then applied Otsu thresholding. How to use the OTSU Threshold in opencv? I was using a fixed threshold but turns out that it's not so good for me. a two-class segmentation can be performed by finding a single threshold that separates the two classes. For the image on the right a global threshold level 41 has been determined using the luminance of the pixels and applied to each channel separately. It maximizes "between class variance" of the segmented classes. The original image in the left. Finally extensive tests are performed and the experiments show that our method obtain more satisfactory results than the original Otsu thresholding algorithm. 1 Traditional Thresholding (Otsu’s Method) In image processing, segmentation is often the first step to pre-process images to extract objects of interest for further analysis. THRESH_OTSU. Although the Otsu segmentation method requires several scanline measurements to be collated before obtaining the binary detection, the segmentation result of the Otsu approach is much cleaner than that of static thresholding, but the features which are farther away with marginal measurements and near the background noise level, cannot be detected by the classic Otsu Then apply Otsu threshold to each of the channels, and merge those channels. In this article you will see how to apply another important technique with the OpenCV library – the Otsu’s binarization. In computer vision and image processing, Otsu's method is used to automatically perform histogram shape-based image thresholding, or, the reduction of a graylevel image to a binary image. Otsu’s thresholding method is the most commonly used method for image binarization using a global threshold [1]. There is an example of yours in the link i sent you yesterday, it had the closest example on how i want setup a threshold, all i want it to do is output smile image if distance is less than threshold and output neutral image if distance is greater than threshold. ), because the first component of such color spaces is luminance (or lightning). … Package ‘autothresholdr’ July 8, 2019 Type Package Title An R Port of the 'ImageJ' Plugin 'Auto Threshold' Version 1. If Otsu thresholding is not used, retVal is same as the threshold value you used. In the previous post, Simple Thresholding was explained with different types of thresholding techniques. 278-282)-Ameasure of region homogeneity is variance (i. GaussianBlur ( img_gray, ( blockSize, blockSize), gaussianStdDeviation) ret, img_blur_otsu_thresh = cv2. Any information about Otsu's algorithm and any feedback about my code helps. They are both based on a same criterion that minimizes the within-class variance. This algorithm chooses the threshold to minimize the intraclass variance of the black and white pixels. threshold ( img_blur, threshold, maxval, globalThresholdType + otsuThresholdType) #Create a Window #cv2