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POMATLAB Image Processing - Find Edge and Area of Image
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copied!<p>As a preface: this is my first question - I've tried my best to make it as clear as possible, but I apologise if it doesn't meet the required standards.</p> <p>As part of a summer project, I am taking time-lapse images of an internal melt figure growing inside a crystal of ice. For each of these images I would like to measure the perimeter of, and area enclosed by the figure formed. Linked below is an example of one of my images:</p> <p><img src="https://i.stack.imgur.com/j8o2K.jpg" alt="enter image description here"></p> <p>The method that I'm trying to use is the following:</p> <ol> <li>Load image, crop, and convert to grayscale</li> <li>Process to reduce noise</li> <li>Find edge/perimeter</li> <li>Attempt to join edges</li> <li>Fill perimeter with white</li> <li>Measure Area and Perimeter using regionprops</li> </ol> <p>This is the code that I am using:</p> <pre><code>clear; close all; % load image and convert to grayscale tyrgb = imread('TyndallTest.jpg'); ty = rgb2gray(tyrgb); figure; imshow(ty) % apply a weiner filter to remove noise. % N is a measure of the window size for detecting coherent features N=20; tywf = wiener2(ty,[N,N]); tywf = tywf(N:end-N,N:end-N); % rescale the image adaptively to enhance contrast without enhancing noise tywfb = adapthisteq(tywf); % apply a canny edge detection tyedb = edge(tywfb,'canny'); %join edges diskEnt1 = strel('disk',8); % radius of 4 tyjoin1 = imclose(tyedb,diskEnt1); figure; imshow(tyjoin1) </code></pre> <p>It is at this stage that I am struggling. The edges do not quite join, no matter how much I play around with the morphological structuring element. Perhaps there is a better way to complete the edges? Linked is an example of the figure this code outputs:</p> <p><img src="https://i.stack.imgur.com/DLEYm.jpg" alt="enter image description here"></p> <p>The reason that I am trying to join the edges is so that I can fill the perimeter with white pixels and then use regionprops to output the area. I have tried using the imfill command, but cannot seem to fill the outline as there are a large number of dark regions to be filled within the perimeter. </p> <p>Is there a better way to get the area of one of these melt figures that is more appropriate in this case?</p> <p>As background research: I can make this method work for a simple image consisting of a black circle on a white background using the below code. However I don't know how edit it to handle more complex images with edges that are less well defined.</p> <pre><code>clear all close all clc %% Read in RGB image from directory RGB1 = imread('1.jpg') ; %% Convert RPG image to grayscale image I1 = rgb2gray(RGB1) ; %% Transform Image %CROP IC1 = imcrop(I1,[74 43 278 285]); %BINARY IMAGE BW1 = im2bw(IC1); %Convert to binary image so the boundary can be traced %FIND PERIMETER BWP1 = bwperim(BW1); %Traces perimeters of objects & colours them white (1). %Sets all other pixels to black (0) %Doing the same job as an edge detection algorithm? %FILL PERIMETER WITH WHITE IN ORDER TO MEASURE AREA AND PERIMETER BWF1 = imfill(BWP1); %This opens figure and allows you to select the areas to fill with white. %MEASURE PERIMETER D1 = regionprops(BWF1, 'area', 'perimeter'); %Returns an array containing the properties area and perimeter. %D1(1) returns the perimeter of the box and an area value identical to that %perimeter? The box must be bounded by a perimeter. %D1(2) returns the perimeter and area of the section filled in BWF1 %% Display Area and Perimeter data D1(2) </code></pre>

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