Discussion: [Numpy-discussion] Python equivalent of bwboundaries, bwlabel. boundaries = bwboundaries (BW_filled); Plot the borders of all of the coins over the original grayscale image. bwboundaries es compatible con la generación de código C (requiere MATLAB ® Coder™). 41 2. numCols = size (BW,2); col = ; row = find (BW (:,col),1) In this example, use a threshold of 0. Description. obj_boundaries = bwboundaries(obj_labelmap, 'noholes'); I'd expect to work in the same way. The example then calculates the row coordinate of the topmost object in that column. The example then calculates the row coordinate of the topmost object in that column. BW is a 2-D binary image where pixels that are logical true belong to the foreground region and pixels that are logical false constitute the background. I established their numbers using a Matlab script. visboundaries uses bwboundaries to find the boundary pixel locations in the image. That information is contained in the fourth output A, an adjacency matrix that represents the parent-child-hole dependencies. Then save that with imwrite (). How do I use a picture from a satellite to compute this area using bwboundaries? transforming the image into binary image? I await response. How to filter objects based on size. BW is a 2-D binary image where pixels that are logical true belong to the foreground region and pixels that are logical false constitute the background. OpenCV only produces each piece of information individually, and there's no guarantee that the labels map from. The code I used for findContours is:Description. The bwboundaries returns the possible boundaries in the input image as a cell array. The bwmorph function performs morphological closing using the neighborhood ones (3). The default of 0. The example then calculates the row coordinate of the topmost object in that column. Axis scaling in matlab. Unlike the convex hull, the boundary can shrink towards the interior of the hull to envelop the points. Share. However, I just wanna find the boundary of last 30 percent of it. Because the variable returned from bwboundaries() is weird, I'm having a lot of difficulties implementing the algorithm. Learn more about image processing, image analysis, image segmentation, ophthalmology, eye, retina, fundus Image Processing Toolbox. I need to find a specific point on an image in MATLAB, where the object I need to measure 'starts'. boundary () has an optional "shrink factor" that chooses the blend between convex hull (s = 0) and something fairly close fitting (s = 1). bw (ismember (labels, [2 3]) = white; %fill pixels whose labels are 2 or 3 with white. You can see this by examining it: >> BW = ~imbinarize (Image. output_axis);. [imagePoints,boardSize] = detectCheckerboardPoints (I) detects a black and white checkerboard of size greater than 4-by-4 squares in a 2-D truecolor or grayscale image. ( more or less) just. 0. To do this, you can use the imfill () function with the 'holes' setting on. Compare the circularity measurement to the threshold. For this example, select a column coordinate. I have used bwboundaries to find the boundaries of all the plants. After finding boundaries of my regions of interest in an RGB image I want to fill them with specific color on the original picture. The output of bwboundaries and getExactBounds may have different lengths. It arbitrarily mixes some labels up, so that obj_boundaries(1) may correspond to the region labeled with 5 (or any other). I'll update my post. The function returns B, a cell array of boundary pixel locations. ' PropertyName',PropertyValue. Each cell in the cell array contains a Q-by-2 matrix. The matrix has twice as many rows as we need, because bwboundaries traces all the way around the object. MATLAB Language Fundamentals Matrices and Arrays Matrix Indexing. Theme. % These are the half widths. Only, now this is creating a bounding box for every object in my image. The reducepoly function uses the Ramer-Douglas-Peucker line simplification algorithm, removing points along straight lines and leaving only knickpoints (points where the line curves). Morphological dilation on Greyscale image using a neighborhood of size n x n in MATLAB. % Column 1 is rows, or y. B = bwboundaries (BW) traces the exterior boundaries of objects, as well as boundaries of holes inside these objects, in the binary image BW . Improve this answer. Hi, In this example below the labeled objects are shown using the jet colormap, on a gray background, with region boundaries outlined in red. Learn more about image processing, image analysis, polygon, bwboundaries, boundary Image Processing Toolbox I have a binary image and I used the bwboundaries to extracted several boundaries from the image. There are six different patterns, each representing a different area:Accepted Answer. visboundaries (BW) draws boundaries of regions in the binary image BW on the current axes. Only inner boundaries are obtained. k = boundary (x,y) returns a vector of point indices representing a single conforming 2-D boundary around the points (x,y). I mean, the image C and the plots on the image. Tags matrix; center; Products MATLAB; Community Treasure Hunt. Secondly, I got the outline coordinates along these two contours using the edge() function. bwboundaries関数についてです。. You could just fill holes in the binarized labeled image, then relabel if you want. 二値化画像のクリーンナップを行ったあと、bwboundaries関数を使いたいのですが、うまくいきません。. 94; Loop over the detected boundaries. bwboundaries: Explanation of a example. An image is choosen so that it has considerable contrast with its background so that the objects can be identified. 98 to an example in the matlab documentation here. MATLAB Graphics 2-D and 3-D Plots Data Distribution Plots. Find the minimum x and y values of your coordinates. BW2 = bwareafilt (BW,n) keeps the n largest objects. bwboundaries returns a cell array, where each cell contains the row and column coordinates for an object in the image. MATLAB has bwboundaries, which produces both a label map and a list of contours at once. Learn more about bwboundaries, image, image analysis, image acquisition, image segmentation, label2rgb, boundary, plot, plotting MATLAB Hi. bwboundaries also traces the exterior and hole boundaries of children objects completely enclosed by parent objects. example. Get the outer boundaries by using matlab function: k = boundary(x,y) Use poly2mask to convert the boundary into a binary image (image2. The problem may just be with either the way you save or with way you used bwboundaries. Select a Web Site. Matlab- Improve code in image cropping black border. visboundaries(BW) draws boundaries of regions in the binary image BW on the current axes. I am trying to search for a specific coordinate point (I want the x value for all coordinates in the boundary that have y=constant). bwboundaries also traces the exterior and hole boundaries of children objects completely enclosed by parent objects. For example, to return the coordinates for the pixels in object 2, enter the following:. , R. % Plot the borders of all the coins on the original grayscale image using the coordinates returned by bwboundaries. text(x,y,'string') adds the string in quotes to the location specified by the point (x,y). Find more on Matrix Indexing in Help Center and File Exchange. Display the image with the inserted recognized text. Hi, In this example below the labeled objects are shown using the jet colormap, on a gray background, with region boundaries outlined in red. Then I applied otsu segmentation to differentiate the background, then bwboundaries. I propose a new procedure in imgproc:. 2 Binary image in. If your version of MATLAB is older than that, it will not know the 'MaxFeretProperties' option. Answers (3) Image Analyst on 27 Nov 2018. I edited this answer to clarify the language, “Width” and “height” refer to the dimensions after rotating the shape so that its smallest projection is horizontal. I noticed that I have a shift of the outline compered to the original object location. C. Then shrink it a bit with imerode() to exclude the outer ring. Then use poly2mask and IA/my steps from above. In the for loop, you can vectorize it and use min(). Typo Walter: bwboundaries(I==8) Sign in to comment. png'); BW=~im2bw (img,0. If you don't want the "whole image" then what do you want? Dishant's code basically does the same as bwperim() - it gives you an image where the boundaries are white/true/1 and the rest is black/false/0. Since I do analysis on a region-of-interest, I have another separate function to return the actual pixel coordinates for given ROI-coordinates. bwboundaries: Explanation of a example. It returns a vector that contains the linear indices. El uso de una biblioteca compartida mantiene. grayImage = imread ('picture'. Parameter connectivity is very important for function bwboundaries. Then save that with imwrite (). threshold = 0. For 2D data, the bwboundaries function does this very well. then dummy_image after the cutoff loop would still be 0 (for the brighter places) and 32 (for the darker places), but that would be uint8. I want to describe the issue in more general terms here as a conflict between the. Run around that border taking a section of the curve, say 9 elements, and fit a polynomial to it. Why doesn't region props pick up the inner boundary when bwboundaries identifies this as a second boundary and how do I find this using code? Image attached to help and code below. boundaries = bwboundaries (BW_filled); Plot the borders of all of the coins over the original grayscale image. y = sgolayfilt (x,order,framelen) applies a Savitzky-Golay finite impulse response (FIR) smoothing filter of polynomial order order and frame length framelen to the data in vector x. Like I said below, use bwboundaries. There is a Matlab script to update former code to fit the way histogram is called (bin edges instead of bin centers - link). It seems straightforward enough, and all works well until I try to plot the boundaries. Share. bwboundaries returns a cell array, where each cell contains the row and column coordinates for an object in the image. BW must be a binary image where. The example then calculates the row coordinate of the topmost object in that column. – Cris Luengo. Hello, I'm having weird trouble with the function bwboundaries. Step 6: Edge Detection Process (Compute Gradient approximation and magnitude of vector) Step 7:. Because the variable returned from bwboundaries() is weird, I'm having a lot of difficulties implementing the algorithm. Improve this answer. I am looking for any method/function that can help me to estimate boundary (red) exactly as the original boundary (blue) from pixel-based coordinate space. example. binaryImage = imfill (labeledImage > 0, 'holes'); [binaryImage, numberOfBlobs] = bwlabel (binaryImage); Change connectivity from 4 to 8 or vice versa to see what effect that has. You could also try morphological operations like imopen() to see if you can cut off some of the bright background that intrudes into the shape and gives it a ragged boundary. obj_boundaries = bwboundaries(obj_labelmap, 'noholes'); I'd expect to work in the same way. visboundaries uses bwboundaries to find the boundary pixel locations in the image. Multi-dimensional version of bwboundaries. % In each cell is an N-by-2 list of coordinates in a (row, column) format. (A cell array is one where each element of the array is a matrix itself). Beware that none of the 6 ways of creating bins with this new function will produce the bins hist and histc produce. BW = imread ('blobs. Step 1: Input – Read an image. . Create text object in current axes. It does not have any information embedded in it about how matrix subscripts relate to some real-world coordinate system. You can get the boundary of your binary image with bwboundaries. The function returns B, a cell array of boundary pixel locations. Find the treasures in MATLAB Central and discover how the community can help you! Start Hunting!The documentation says the following about the return value of bwboundaries(): bwboundaries returns B, a P-by-1 cell array, where P is the number of objects and holes. 9689. Any specific boundary can be extracted by indexing the cell array. bwareafilt returns a binary image BW2 containing only those objects that meet the criteria. bw (ismember (labels, [2 3]) = white; %fill pixels whose labels are 2 or 3 with white. i plotted it as a boundary detection ,but if i remove it as your answer this will remove it from this figure only , but not will be removed from the original image. Sign In to Your MathWorks Account; My Account; My Community Profile; Link License. The function returns B, a cell array of boundary pixel locations. You can do it simply with imcontour or bwboundaries. To do this you must first crop out the original image using the ' imcrop ' function. 0. %% Find the boundaries. bwboundaries also traces the exterior and hole boundaries of children objects completely enclosed by parent objects. What I'd start with is to get the boundary with bwboundaries() and then to use interp1() to make the boundary some known number of points, like 10 thousand points. This operation is known as an area opening. Yes, he wants MATLAB code, that is the entire purpose of tags in Stackoverflow. Gray world assumption is based on the principal that on average the world is gray. Learn more about image processing Image Processing Toolbox This simple example is given in the Matlab Documentation: I = imread('rice. The bwboundaries function implements the Moore-Neighbor tracing algorithm modified by Jacob's stopping criteria. Get the outer boundaries by using matlab function: k = boundary (x,y) Use poly2mask to convert the boundary into a binary image (image2. Copy. The label2rgb function determines the color to assign to each object based on the number of objects in the label matrix. Learn more about image processing Image Processing ToolboxSince you have the Image Processing Toolbox, an easy way to do this is with bwperim or bwboundaries. You can use the MATLAB ® find function in conjunction with bwlabel to return vectors of indices for the pixels that make up a specific object. If your version of MATLAB is older than that, it will not know the 'MaxFeretProperties' option. Set the first nonzero pixel as S (Starting of the boundary) Set the current pixel as p ; Add this non zero pixel into a boundary pixel list. If no feature is detected, I simply return NaNs. >> B=bwboundries(bw); bwboundaries returns B, a P-by-1 cell array, where P is the number of objects and holes. Copy. b = boundaries{1}; b =. Once you have the binary image, you can use the ' bwboundaries ' function to obtain the boundary pixels. Theme. 2) If you can solve the problem in (2. labels = bwlabel (bw); white = uint8 (255); %or 1 if your image is double. The question relates to the tracing of a boundary in a binary image. averageWidth = 2 * mean (radii) averageWidth = single 11. Compute two boundaries: one with a shrink factor of 0 and the other with a shrink factor of 1. Parameter connectivity is very important for function bwboundaries. It estimates each object's area and perimeter and uses these results to form a simple metric indicating the roundness of an object with the following metric: metric = 4*pi*area/perimeter^2Get the outer boundaries by using matlab function: k = boundary (x,y) Use poly2mask to convert the boundary into a binary image (image2. I want to grab this curves as a list of points (in proper order). The points (x(k),y(k)) form the boundary. I've used the function "bwboundaries" on a binary image but I can't seem to figure out how to find the area enclosed by the boundary output, B. You can create a polyshape from a collection of polygons that bound individual regions and holes, and the Image Processing Toolbox function bwboundaries can produce just such a list of polygons. I haven't been able to find a. Learn more about image processing, image analysis, image segmentation, ophthalmology, eye, retina, fundus Image Processing Toolbox. png)Open the Impedance Calculator App. i want to remove it from original image also not from the displayed figure only . . . You only need the first step of the bwboundaries algorithm, which is the region labels obtained with bwlabel. text is the low-level function for creating text graphics objects. The function returns B, a cell array of boundary pixel locations. I am using 'bwboundaries. Description. The function imread reads the image from a given location and stores it in the. Axes like wblplot when plotting X and Y in Matlab. Sign in to comment. k = boundary (P,0); j = boundary (P,1); Compare the shrink factors by plotting the. If objects in score are ordered in the same way as the objects generated by regionprops then this is ok, since regionprops and bwboundaries index objects in the same order. Then, we trace through the boundary in clockwise direction, using Moore neighborhood approach until we reach the starting pixel again. Simple extract the green channel, threshold, and call bwboundaries. Modified 11 years ago. regionprops supports both contiguous regions and discontiguous regions. BW must be a binary image where. By default the boundaries are computed using. Assuming you have the initial green boundary, you can convert it into a binary image and then use imdilate or imerode to grow or shrink the boundary. Learn more about image processing, bubbles, foam, bwboundaries, post processing, image analysis, object properties, area of bubble MATLAB, Image Processing Toolbox. Learn more about image processing, digital signal processing, bwboundaries Image Processing ToolboxPick a point on the boundary of a second object. @JohnSal: that multiplication rotates the polygon in ConvexHull. The function returns B, a cell array of boundary pixel locations. Low. To trace the boundary of a single object in the binary image, first determine the row and column coordinates of a pixel on the border of the object. Read a binary image into the workspace. numCols = size (BW,2); col = ; row = find (BW (:,col),1)Get the outer boundaries by using matlab function: k = boundary (x,y) Use poly2mask to convert the boundary into a binary image (image2. The LS estimation is done for the conic representation of an ellipse (with a possible tilt). When generating code, if you specify color as a character vector, then the value must be a compile-time constant. [H,theta,rho] = hough (BW) computes the Standard Hough Transform (SHT) of the binary image BW. png) Move bwboundaries (x,y) to origin (0,0), move centroid, move major axis , and apply a scale factor to bwboundaries in order to match. bwboundary uses this point as the starting location for the boundary tracing. To my knowledge, OpenCV doesn't have that. Note that if you choose the generic MATLAB Host Computer target platform, bwboundaries generates code that uses a precompiled, platform-specific shared library. 94 so that only the pills will be classified as round. Viewed 176 times 2 In the script below I outline an object but in the final plot. Function. Find more on Data Distribution Plots in Help Center and File Exchange. CC struct. This image is vital for painting the pixels to display this on. 1. img=imread ('I. – beaker. answered May 25, 2012 at 17:15. The following is my code to first create the single boundary line by searching for the bottom left pixel of the black area to begin the trace. If you shrink and tighten the convex hull from above, you can enclose all of the points in a nonconvex. If x is a matrix, then sgolayfilt operates on each column. Step 3: Convert the image to double. Yes. % Plot all the boundaries on the original grayscale image using the coordinates returned by bwboundaries. Find more on Matrix Indexing in Help Center and File Exchange. % using the coordinates returned by bwboundaries(). Finding Centroid and Area bwboundaries It traces the exterior boundries of objects in Binary image. function bwboundaries is working just fine, however I wanted to ask if there is a way to differentiate between different boundaries, for example if there is a way to group boundaries between. Algorithm: Traverse 2D matrix in row wise. For this i want develop algorithm dynamically. Matlab- Improve code in image cropping black border. It's possible you're simply looking for the L matrix returned by bwboundaries. If A and B are tables or timetables, then intersect returns the set of rows common to both tables. Only inner boundaries are obtained. numCols = size (BW,2); col = ; row = find (BW (:,col),1)In this example, use a threshold of 0. numCols = size (BW,2); col = ; row = find (BW (:,col),1)This assumes that the score array is ordered in the same way as the objects array generated by bwboundaries. J = imclearborder (I) suppresses structures in the image I that are lighter than their surroundings and connected to the image border. Find the treasures in MATLAB Central and discover how the community can help you! Start Hunting!Learn more about bwboundaries Image Processing Toolbox. You can see this by examining it: >> BW =. Image segmentation in matlab. With the smooth image, we can clean up the noise by using bwboundaries(), imclearborder(), and bwareaopen() consecutively one after the other. 1. bwboundaries and axes - Matlab. L. Find the minimum x and y values of your coordinates. Find the treasures in MATLAB Central and discover how the community can help you! Start Hunting!A polyshape is an object that can represent shapes that are composed of polygons. Learn more about image processing Image Processing ToolboxHi, I'd like to plot the object boundaries of an image shown in a figure. But you have both the binary image and the boundaries. 2. If x is a matrix, then sgolayfilt operates on each column. Cameron Walsh. This function is based on the boundaries function presented in the first edition of Digital Image Processing Using MATLAB, by Gonzalez, R. 0. You can get the boundary of your binary image with bwboundaries. Adding the 'MaxFeretProperties' option to regionprops will add three features to the output struct. The example then calculates the row coordinate of the topmost object in that column. Answers (1) This is expected. bw2 = padarray (bw, [1 1],0, 'pre' );MATLAB图像处理边缘检测. As the L is of all the image not of specific object, is it possible to get it for an object?. If the polygon is not already closed, then. Convert the image to a binary image. bwboundaries also traces the exterior and hole boundaries of children objects completely enclosed by parent objects. – beaker Feb 13, 2022 at 19:43 Added an image. Learn more about matlab, boundary Image Processing Toolbox. I propose a new procedure in imgproc:. C. Feb 13, 2022 at 19:43. boundaries is a cell array in which each element is the boundary of an object in the binary image BW. example. 1. I want to know,how to fill the traced region alone with white pixels. Find the treasures in MATLAB Central and discover how the community can help you! Start Hunting! Es ist ein Fehler aufgetreten. I have a MATLAB script that gives me the boundary lines of an image using bwboundaries(). plz give a suggestion how i code this to achive my goal or how i will have to run the loop for. outermost objects (parents) and traces their children (objects. ~ is logical negation in this context. 1. visboundaries (BW) draws boundaries of regions in the binary image BW on the current axes. Trace the boundaries of all coins in the image by using the bwboundaries function. numCols = size (BW,2); col = ; row = find (BW (:,col),1) 2. 1. I also want the x,y coordinates of each pixel INSIDE the boundaries also. mask = poly2mask (x, y, rows, columns); bigMask = imdilate (mask, true (3)); bigBoundary = bwboundaries (bigMask); smallMask = imerode (mask, true (3));. Show -1 older comments Hide -1 older comments. png'); BW = im2bw(I, graythresh(I)); B = bwboundaries(BW,'noholes'); for k = 1:length(B) boundary = B. bwboundaries also traces the exterior and hole boundaries of children objects completely enclosed by parent objects. Da Änderungen an. Find the treasures in MATLAB Central and discover how the community can help you! Start Hunting!Practice. However, the boundaries that are found using bwboundaries are very rough and jagged. visboundaries uses bwboundaries to find the boundary pixel locations in the image. png figure); 2) the red curve that creates the. For 2-D problems, k is a column vector of point indices representing the sequence of points around the boundary, which is a polygon. Step 5: Define Sobel Operator Mask. bwboundaries also traces the exterior and hole boundaries of children objects completely enclosed by parent objects. Below code segment shows the result correctly on output_axis. bwboundaries: Explanation of a example. Then take the mean or sum of those closest distances. Trace the boundaries of all coins in the image by using the bwboundaries function. bwthresh selects areas with grey scale above a certain level; ~BW would then be everywhere with grey scale below that level. 0. For more information, see Pixel Connectivity. Need to have object & background labeled as 1, -1 (not 1,0) Inner boundary: gives the locations of the outermost pixels of the object bwtraceboundary bwboundaries (for multiple objects)actually i need your help in "how to find the white pixel that has minimum x and minmum y cordinates. png'); imshow (BW, []);Anyway, I'd try bwskel() after the thick edge call and hopefully that won't break the lines. Description example k = boundary (x,y) returns a vector of point indices representing a single conforming 2-D boundary around the points (x,y). help with bwboundaries() function ?. Assuming you have the initial green boundary, you can convert it into a binary image and then use imdilate or imerode to grow or shrink the boundary. Learn more about digital image processing, binary, image segmentation, boundary, bwboundaries Image Processing ToolboxImage Analyst on 14 May 2012. png) Get the bwboundaries of the binary image; Find centroid and major axis using regionprops (image2. By default the boundaries are computed using. So, because you passed it a gray scale image, it took the white part as the foreground region and visboundaries () drew the boundaries around the white regions. visboundaries uses bwboundaries to find the boundary pixel locations in the image. The example then calculates the row coordinate of the topmost object in that column. visboundaries (BW) draws boundaries of regions in the binary image BW on the current axes. completely enclosed by the parents). png) Plot bwboundaries, major axis and centroid (image3. b = bwboundaries (mask4) b = 9×1 cell. L. Once you have the binary image, you can use the ' bwboundaries ' function to obtain the boundary pixels. It arbitrarily mixes some labels up, so that obj_boundaries(1) may correspond to the region labeled with 5 (or any other). When I applied your code, the image would become black-and-white, because of the function "bwboundaries" i guess, and I would like to add the boundary line only and to display the result in colour. To ensure that bwboundaries traces only the exterior of the coins, fill the area inside each coin by using the imfill function. numCols = size (BW,2); col = ; row = find (BW (:,col),1) La fonction bwboundary est une fonction qui à partir d'une image en niveau de gris (noir et blanc), va te donner 4 paramètres de sorties dont les deux premiers (les deux intéressants pour toi) sont: -les coordonnées du contour de chaque objet présent sur ton image en niveau de gris. So do the functions exist in C++, ruby, perl and whitespace. Description. % found by the edge detector you may want to evaluate. bwboundaries는 부모 객체에 완전히 둘러싸인 자식 객체의 외부 경계선과 구멍 경계선도 추적합니다. 1. To do this, you can use the imfill () function with the 'holes' setting on. BW2 = bwareaopen (BW,P,conn) removes all connected components, where conn specifies the desired connectivity. I see there's findContours in OpenCV, but it is not giving the same results as bwboundaries is. What I am interested in doing are the following steps: 1) Determine the centroid of the image - This step is easy enough using regionprops. edtImage = bwdist (~BWc); %Distance of to nearest 0 value. For 2-D problems, k is a column vector of point indices representing the sequence of points around the boundary, which is a polygon. I would like to be able to improve the following code so that: 1) the background always remains white and the curves always black (such as the . bwboundaries: Explanation of a example. Copy. Find the treasures in MATLAB Central and discover how the community can help you! Start Hunting!I've updated my question with a picture of the results. For example, figure;imshow (I) roi = round (getPosition (drawrectangle)) Recognize text within the ROI. How to Extract part of. Learn more about image processing, matrix manipulation, matrix array MATLAB and Simulink Student Suite, Image Processing Toolbox This is the code. If you want the boundaries as an image instead of an N-by-2 list of (x,y) coordinates, then call bwperim(). Then just set those coordinates to zero in your original image and your binary image. 14 years ago. Use of a shared library preserves performance optimizations but limits the target platforms for which code. El uso de una biblioteca compartida mantiene las. Or you could use a Savitzky-Golay filter along with bwboundaries () to smooth out the coordinates, then use poly2mask () if you need to turn the coordinates into. Get. Multiply by 2 to get the full widths. For this example, select a column coordinate. png) Move bwboundaries (x,y) to origin (0,0), move centroid, move major axis , and apply a scale factor to bwboundaries in order to match. I am able to get all the edges and draw rectangles around them but I'm struggling with drawing a rectangle around all the rectangles to hopefully use to crop out the object. bwboundaries: Explanation of a example. When I use report>field output, I am getting data that does. B = bwboundaries (BW) traces the exterior boundaries of objects, as well as boundaries of holes inside these objects, in the binary image BW . bwboundaries supports the generation of C code (requires MATLAB ® Coder™). This image contains only one object, so boundaries contains only one P-by-2 matrix. calculating the real average pixel value, the scaling value is computed. Determine the row and column coordinates of a pixel on the border of the object you want to trace. Show 12 older comments. b = bwboundaries (mask4) b = 9×1 cell. This is code I used as my reference: Theme. Nov 15, 2012 at 21:35.