Masking an RGB Image with Binary Mask. C is in sorted order. Image segmentation in matlab. To learn more about geographic data structures, refer to this documentation: Geographic Data Structures - MATLAB & Simulink - MathWorks To write the Geo struct into a Shapefile, you can use a function shapewrite , below is the syntax for that:I next formed a boundary around the image using bwboundaries and marked out the peaks and valleys of the fingers, and I'm trying to estimate where the edge of the little finger is located by finding the distance between the tip of the little finger and the valley between the little finger and the valley between the little finger and the ring finger. The points (x (k),y (k)) form the boundary. How do I use a picture from a satellite to compute this area using bwboundaries? transforming the image into binary image? I await response. Check the other labels and see which objects they correspond to. grayImage = imread ('picture'. But when the line parallel the radii line (same as picture 2) the mean position of x, y and z cannot calculate from mean of radii but you must calculate it from meaning of theta of 3 point. labels = bwlabel (bw); white = uint8 (255); %or 1 if your image is double. boundaries = bwboundaries (BW_filled); Plot the borders of all of the coins over the original grayscale image. ContentsA new file prompts a thought experimentFreeman Chain CodeNicolas's ImplementationImage Processing ToolboxHow does the timing compare?What about more complicated images?A couple of suggestionsA new file prompts a thought experimentI've never done this before, but I've decided to write about a file that just went live. It also descends into the. Discussion: [Numpy-discussion] Python equivalent of bwboundaries, bwlabel. Syntax. bwboundaries also traces the exterior and hole boundaries of children objects completely enclosed by parent objects. boundaries is a cell array in which each element is the boundary of an object in the binary image BW. for k=1:length (B)Link. Once you have the binary image, you can use the ' bwboundaries ' function to obtain the boundary pixels. 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. BW = edge (I,method,threshold) returns all edges that are stronger than threshold. Theme. Just pick which label you want to see, say k, and L==k will be your binary image. If A and B are tables or timetables, then intersect returns the set of rows common to both tables. Furthermore, the output from bwboundaries supplies each boundary as closed (ie, the first XY boundary point is coincident with the last XY boundary point), so I think you can simply pass the results of bwboundary to a Douglas Peucker function, and then use that result directly. bwboundaries returns a cell array, where each cell contains the row and column coordinates for an object in the image. Hi all, I'm trying to do object segmentation from image slices, and have found the. Find the treasures in MATLAB Central and discover how the community can help you! Start Hunting!Learn more about bwboundaries Image Processing Toolbox. To do this, you can use the imfill () function with the 'holes' setting on. Matlab GUI axes to figure. Then subtract off the values you added. (Tilt/orientation for the ellipse occurs when the term x*y. The function returns B, a cell array of boundary pixel locations. BW2 = imfill (BW,'holes'); EDIT: Looking at the code, it seems that it does what you want already. Simple extract the green channel, threshold, and call bwboundaries. BW2 = imfill (BW) displays the binary image BW on the screen and lets you define the region to. To my knowledge, OpenCV doesn't have that. MATLAB Language Fundamentals Matrices and Arrays Matrix Indexing. Trace the boundaries of all coins in the image by using the bwboundaries function. –% using the coordinates returned by bwboundaries(). Sorted by: 1. what i want to say is explained in attach figure. For this example, select a column coordinate. boundary () has an optional "shrink factor" that chooses the blend between convex hull (s = 0) and something fairly close fitting (s = 1). 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. . This example shows how to find the perimeter pixels in a binary image using the bwperim function. 1) As I said, your labeling might be different. Learn more about bwboundaries regionprops MATLAB I have a requirement to find the area and perimeter of 2 circular boundaries and also to display these boundaries over a copy of the original non-binary image. 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. Meshooo observed a discrepancy between the output of bwboundaries and the mask created by createMask. Copy. All of the objects in L are labeled. – beaker Feb 13, 2022 at 19:43 Added an image. How to Extract part of. Parameter connectivity is very important for function bwboundaries. bw2 = padarray (bw, [1 1],0, 'pre' );MATLAB图像处理边缘检测. imcomplement applied to uint8 is 255 - value, so after the imcomplement the values would be 255 (for the brighter places) and 223 (for the darker places), data type uint8. Ask Question Asked 12 years, 8 months ago. png) Find centroid and major axis using regionprops (image2. 1. g. If x is a matrix, then sgolayfilt operates on each column. % bwboundaries() returns a cell array, where each cell contains the row/column coordinates for an object in the image. jpg拡張子の画像を読み込ませています。. 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. 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. It's possible you're simply looking for the L matrix returned by bwboundaries. ) h = text(. bw (ismember (labels, [2 3]) = white; %fill pixels whose labels are 2 or 3 with white. The candidate routines were the above-mentioned findcontours routine and the bwboundaries routine, which is part of the image processing toolbox of MATLAB . I have a set of images of bubbles all next to each other but where the contour lines are well visible. Use this function to clear the image border or select image borders. Theme. k = boundary (x,y) returns a vector of point indices representing a single conforming 2-D boundary around the points (x,y). wow, yes I was making a simple mistake with that. png)It's very simple and is basically 3 or 4 steps. Learn more about image processing Image Processing Toolbox This simple example is given in the Matlab Documentation: I = imread('rice. visboundaries uses bwboundaries to find the boundary pixel locations in the image. [X,Y]=find (Iedge==1);Hi I would appreciate if you answer my questions. As the L is of all the. How to filter objects based on size. It returns a vector that contains the linear indices. 5); B = bwboundaries (a2); for k = 1:length (B) boundary = B {k}; % here should color everything inside boundary in. As before, I will convert this to black and white and trace out the boundaries using bwboundaries from the Image Processing Toolbox. I established their numbers using a Matlab script. Once you have the binary image, you can use the ' bwboundaries ' function to obtain the boundary pixels. [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. bwpropfilt returns a binary image BW2 containing only those objects that meet the criteria. This MATLAB function traces the exterior boundaries of objects, as well as boundaries of holes inside these objects, in the binary image BW. Copy. Then to get the number of connected components:grayImage = imread (fullFileName); % Get the dimensions of the image. visboundaries uses bwboundaries to find the boundary pixel locations in the image. Low. The function returns B, a cell array of boundary pixel locations. It almost does, but only for about 80% of the labels. 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. Description. If you really want to use bwboundaries, you have to create an image (full size black image) then go down the list you got from bwboundaries, setting each coordinate to white. mask = bwconvhull (mask); % Here is where we actually get the boundaries for each blob. I2 = imfill (I,conn) fills holes in the grayscale image I, where conn specifies the connectivity. mask = poly2mask (x, y, rows, columns); bigMask = imdilate (mask, true (3)); bigBoundary = bwboundaries (bigMask); smallMask = imerode (mask, true (3)); smallBoundary = bwboundaries. bwconncomp uses significantly less memory and is sometimes faster than the other functions. Another possibility is to use the BWBOUNDARIES function, which:. E. visboundaries (BW) draws boundaries of regions in the binary image BW on the current axes. 0 Comments. scilab - Drawing bounding box. As we know bwboundaries function determines the boundary pixels of the objects but in my case, it loses lots of potential pixels which shouldn't be. 0. Improve this answer. Learn more about matab, bwboundaries, color MATLAB bwboundaries関数を用いた際に多くの色が用いられ、色分けされますが、プログラムの中に、色を指定するような部分は見られず、どのように色が出てきているので. E. numCols = size (BW,2); col = ; row = find (BW (:,col),1) 2. Find the treasures in MATLAB Central and discover how the community can help you! Start Hunting!MATLAB's bwboundaries command which returns contours in ij format (row coordinates in the first column, column coordinates in the second). 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. % bwboundaries() returns a cell array, where each cell contains the row/column coordinates for an object in the image. img=imread ('I. boundaries is a cell array in which each element is the boundary of an object in the binary image BW. Use bwboundaries () to get the coordinates of the outline of your blob (human). I haven't been able to find a. I need to find a specific point on an image in MATLAB, where the object I need to measure 'starts'. The example then calculates the row coordinate of the topmost object in that column. If you really want to use bwboundaries, you have to create an image (full size black image) then go down the list you got from bwboundaries, setting each coordinate to white. 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. 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 . visboundaries uses bwboundaries to find the boundary pixel locations in the image. I want to describe the issue in more general terms here as a conflict between the. . I want to describe the issue in more general terms here as a conflict between the geometry of the bwboundaries function and the geometry of the poly2mask Theme. C = intersect (A,B) returns the data common to both A and B , with no repetitions. The question relates to the tracing of a boundary in a binary image. . Try cvContours () function. bwboundaries returns a cell array, where each cell contains the row and column coordinates for an object in the image. traces the exterior boundaries of objects, as well as boundaries of holes inside these objects. boundaries = bwboundaries (BW_filled); Plot the borders of all of the coins over the original grayscale image. bwboundaries returns a cell array, where each cell contains the row and column coordinates for an object in the image. To learn more about geographic data structures, refer to this documentation: Geographic Data Structures - MATLAB & Simulink - MathWorks To write the Geo struct into a Shapefile, you can use a function shapewrite , below is the syntax for that:Below code segment shows the result correctly on output_axis. bwboundaries also traces the. MATLAB axes have constant values. Only inner boundaries are obtained. Added an image. B = bwboundaries(BW) traces the exterior boundaries of objects, as well as boundaries of holes inside these objects, in the binary image BW. 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. visboundaries uses bwboundaries to find the boundary pixel locations in the image. (A cell array is one where each element of the array is a matrix itself). This assumes that the score array is ordered in the same way as the objects array generated by bwboundaries. If I understand you correctly, you have a binary image of the boundary of the kidney and now need to set the inside of the boundary to 1s. Theme. You only need the first step of the bwboundaries algorithm, which is the region labels obtained with bwlabel. output_axis);. answered May 25, 2012 at 17:15. bwboundariesの色分けについて. Just use the 4 other lines of code on whatever you called your binary image. % plot the contours of the edges. 0. Any. Display the image with the inserted recognized text. BW = edge (I,method,threshold,direction) specifies the orientation of edges to detect. The default of 0. By. bw (ismember (labels, [2 3]) = white; %fill pixels whose labels are 2 or 3 with white. Perhaps what you should do is to first use kmeans to identify your clusters. Because the variable returned from bwboundaries() is weird, I'm having a lot of difficulties implementing the algorithm. " i want to point out the position of that pixel that is represented by minimum x and minimum y cordinate. Adding the 'MaxFeretProperties' option to regionprops will add three features to the output struct. Answers (2) B = bwboundaries (img2,'noholes');//no holes is required in case of your image. The output stats denotes different properties for each object. Learn more about image processing, bubbles, foam, bwboundaries, post processing, image analysis, object properties, area of bubble MATLAB, Image Processing Toolbox. Tenga en cuenta que, si selecciona la plataforma objetivo genérica MATLAB Host Computer, bwboundaries genera código que utiliza una biblioteca compartida precompilada específica de la plataforma. png'); BW=~im2bw (img,0. CC struct. Learn more about image processing, image analysis, image segmentation, ophthalmology, eye, retina, fundus Image Processing Toolbox. example. You would first need to extract out the pixels that are along that boundary. Only inner boundaries are obtained. Use of a shared library preserves performance optimizations but limits the target platforms for which code. Tags histogram; relative frequency; Community Treasure Hunt. Algorithm: Traverse 2D matrix in row wise. Sign in to comment. example. 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. The bwmorph function performs morphological closing using the neighborhood ones (3). Elysi, now I / we think perhaps you want to extract only the second and third largest blob, considering their size after filling, which is a completely different thing than what were first answering about blob #2 and blob #3 using numbers as gotten from something like bwboundaries() and bwlabel(). B = bwboundaries (BW) traces the exterior boundaries of objects, as well as boundaries of holes inside these objects, in the binary image BW . How to fit an ellipse to an image in matlab. I then use the contours to write them to STL files. bwboundaries also. % numberOfColorBands should be = 1. For 2D data, the bwboundaries function does this very well. After finding boundaries of my regions of interest in an RGB image I want to fill them with specific color on the original picture. We start by padding the image with 0s on the left and top. BW2 = bwareafilt (BW,n) keeps the n largest objects. This example uses the coordinates of a pixel near the upper-left corner of the largest rectangle. 0. example. If the circularity exceeds the threshold, calculate the. imoverlay supports the generation of C code (requires MATLAB Coder™). The find () function in MATLAB is used to find the indices and values of non-zero elements or the elements which satisfy a given condition. 2. Learn more about image processing Image Processing ToolboxWiki: "If after a recent upgrade (libncurses to v 6. J = imclearborder (I) suppresses structures in the image I that are lighter than their surroundings and connected to the image border. 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. As the L is of all the image not of specific object, is it possible to get it for an object?. bw (ismember (labels, [2 3]) = white; %fill pixels whose labels are 2 or 3 with white. Find more on Matrix Indexing in Help Center and File Exchange. visboundaries uses bwboundaries to find the boundary pixel locations in the image. outermost objects (parents) and traces their children (objects. 2. Learn more about image processing, digital signal processing, bwboundaries Image Processing ToolboxPick a point on the boundary of a second object. 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. visboundaries (BW) draws boundaries of regions in the binary image BW on the current axes. The function returns B, a cell array of boundary pixel locations. To give some context to the code below: I am looking for the pixel coordinates (X,Y) of the edge of the largest Blob detected with bwboundaries. The function returns B, a cell array of boundary pixel locations. Then subtract off the values you added. example. Column 2 is columns, or x. I've tried to use both bwtraceboundary and bwboundaries to identify the edge outlines and then export this file with polylines, but am not having any luck. I established their numbers using a Matlab script. OpenCV only produces each piece of information individually, and there's no guarantee that the labels map from. bwconncomp utiliza una conectividad por defecto. Step 4: Pre-allocate the filtered_image matrix with zeros. This image contains only one object, so boundaries contains only one P-by-2 matrix. OpenCV only produces each piece of information individually, and there's no guarantee that the labels map from. 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. The points (x (k),y (k)) form the. png'); BW = im2bw(I, graythresh(I)); B = bwboundaries(BW,'noholes'); for k = 1:length(B) boundary = B. A convex polygon is a polygon that does not have concave vertices, for example: x = rand (20,1); y = rand (20,1); k = convhull (x,y); plot (x (k),y (k)) title ( 'Convex Polygon') You can also create a boundary of a point set that is nonconvex. Chathu on 4 May 2016. bwboundaries: Explanation of a example. Use bwperim () if you want an image of the outer boundary. The bwboundaries function implements the Moore-Neighbor tracing algorithm modified by Jacob's stopping criteria. 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) 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 see there's findContours in OpenCV, but it is not giving the same results as bwboundaries is. MATLAB ® command prompt: Enter powerImpedance (sys), where sys is a string scalar or character vector that is the name of a model. With this principal in mind we deduce that the average pixel value of an Unsigned 8-bit integer image is 127. Step 2: Convert the true-color RGB image to the grayscale image. A= [main1. imshow (I) hold on. The function returns B, a cell array of boundary pixel locations. However, I don't just want the x,y coordinates of each pixel ON the boundaries. Viewed 4k times 0 I just want to trace boundaries in my gray image. 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. The original image is attached as is the code to convert the image to a binary edge-detected image. numCols = size (BW,2); col = ; row = find (BW (:,col),1)In this example, use a threshold of 0. Because the variable returned from bwboundaries() is weird, I'm having a lot of difficulties implementing the algorithm. It's an image of a droplet laying on surface, and I would like to know how to find the x coordinate where the droplet starts. 1. If no feature is detected, I simply return NaNs. y = sgolayfilt (x,order,framelen,weights) specifies a weighting vector to use during the least. bwboundaries(BW,connectivity,options) Return row (y) and column (x) coordinates of boundary pixel locations. Find the minimum x and y values of your coordinates. . Feret properties were added to regionprops in MATLAB R2019a. B = bwboundaries (BW) traces the exterior boundary of objects, as well. 9. The Image Processing Toolbox has a function, imclearborder, for removing all objects touching the image borders. Like I said below, use bwboundaries. b = bwboundaries (mask4) b = 9×1 cell. Use of a shared library preserves performance optimizations but limits the target platforms for which code. I presume your foreground is white and background black. 1. It also descends into the. I2 = imfill (I) fills holes in the grayscale image I. I got problem by getting a region boundary two times. Description. Description. png figure); 2) the red curve that creates the. There is a Matlab script to update former code to fit the way histogram is called (bin edges instead of bin centers - link). To do this, you can use the imfill () function with the 'holes' setting on. Unlike the convex hull, the boundary can shrink towards the interior of the hull to envelop the points. For 2D data, the bwboundaries function does this very well. figure. The output C will be a cell of cells, containing the contours. in that case it can computes only one convhull - it doesn't help a lot. The example then calculates the row coordinate of the topmost object in that column. Copy. Then run around the list of (x,y) edge. This image is vital for painting the pixels to display this on. BW2 = bwareaopen (BW,P) removes all connected components (objects) that have fewer than P pixels from the binary image BW , producing another binary image, BW2. png)Open the Impedance Calculator App. Beware that none of the 6 ways of creating bins with this new function will produce the bins hist and histc produce. Convert the image to a binary image. Now i want the region under the boundary to be masked with green color. bwboundaries 支持 C 代码生成（需要 MATLAB ® Coder™ ）。请注意，如果您选择通用的 MATLAB Host Computer 目标平台，bwboundaries 生成的代码将使用平台特定的预编译共享库。使用共享库可保留性能上的优化，但适用范围仅限于生成的代码所适用的目标平台。Now, if you want to do the subsampling, you would call bwboundaries this way: [bound,L,N] = bwboundaries(B); bwboundaries returns a cell array bound of boundaries where each cell is a N x 2 array of spatial coordinates that define the boundary. Specifying limits of axes. B = bwboundaries(BW) traces the exterior boundaries of objects, as well as boundaries of holes inside these objects, in the binary image BW. Learn more about image processing, matrix manipulation, matrix array MATLAB and Simulink Student Suite, Image Processing Toolbox This is the code. How can Matlab be able to take the positions from bwboundaries and correctly determine the endpoints for the edge on the. – Richard. MATLAB user Meshooo asked a question on MATLAB Answers about a problem with the createMask function associated with impoly. 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). I mean, the image C and the plots on the image. Each row in the matrix contains the row and column coordinates of a boundary pixel. bwareafilt returns a binary image BW2 containing only those objects that meet the criteria. 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. png) Get the bwboundaries of the binary image; Find centroid and major axis using regionprops (image2. 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. For grayscale images, imclearborder tends to reduce the overall intensity level in addition to suppressing border structures. A pixel is part of the perimeter if it is. png figure); 2) the red curve that creates the. Then you can convert the cropped image to binary image using the ' im2bw ' function. Then loop over them and figure out which of the 8 directions the next pixel in the list is and assign a number from 1 to 8 to that pixel. The clockwise boundary of each object is computed by the boundary function. Hi there, I am new in image processing using MATLAB. Now, after plotting that image, I am getting the complete image, formed from various straight line segments. Note: NOT (x,y). Morphological dilation on Greyscale image using a neighborhood of size n x n in MATLAB. Tags matrix; center; Products MATLAB; Community Treasure Hunt. How write Matlab code to plot boundaries of. If x is a matrix, then sgolayfilt operates on each column. Learn more about image, im2bw, array, for loop, bwboundaries, thresholding, outines Image Processing Toolbox. Find the treasures in MATLAB Central and discover how the community can help you! Start Hunting!. bwboundaries: Explanation of a example. You can do it simply with imcontour or bwboundaries. La estructura de salida CC contiene el número total de componentes conectados, tales como las regiones de interés (ROI), de los índices de la imagen y los píxeles asignados a cada componente. This function is based on the boundaries function presented in the first edition of Digital Image Processing Using MATLAB, by Gonzalez, R. At the same time, I plotted the gradient arrows started from the first contour, to show the expanding directions at different sides. For example, figure;imshow (I) roi = round (getPosition (drawrectangle)) Recognize text within the ROI. For timetables, intersect takes row times into account to determine equality, and sorts the output timetable C by row times. Function File: [boundaries, labels, num_labels] = bwboundaries (…) Trace the boundaries of the objects in a binary image. "branchpoints". it will be heighly appricated. Answers (1) The bwboundaries returns the possible boundaries in the input image as a cell array. Copy. bwboundaries also traces the exterior and hole boundaries of children objects completely enclosed by parent objects. Answers (3) Image Analyst on 27 Nov 2018. Find the closest one with min. – beaker. bwtraceboundary and bwboundaries only work with binary images. The bwboundaries function implements the Moore-Neighbor tracing algorithm modified by Jacob's stopping criteria. x) matlab stops working, you will need to make the old 5. In this syntax, a hole is defined as an area of dark pixels surrounded by lighter pixels. Note that masks with contours extracted using bwboundaries that are then directly passed to poly2mask (as in the first example) may have 1-pixel border regions that do not match. Cheers % Convert the image to binary (value to be modified in below section. The matrix has twice as many rows as we need, because bwboundaries traces all the way around the object. For 2-D problems, k is a column vector of point indices representing the sequence of points around the boundary, which is a polygon. 0. bwthresh selects areas with grey scale above a certain level; ~BW would then be everywhere with grey scale below that level. I noticed that I have a shift of the outline compered to. edtImage = bwdist (~BWc); %Distance of to nearest 0 value. Modified 4 years ago. Share. ); Description. As long as the language is turing complete it is ensured to have them. For 2-D problems, k is a column vector of point indices representing the sequence of points around the boundary, which is a polygon. Find more on Matrix Indexing in Help Center and File Exchange. bwboundaries es compatible con la generación de código C (requiere MATLAB ® Coder™). 1. bwboundaries looks for zeros;. Alternatively, you can use drawrectangle to select a region using a mouse. bwboundaries: Explanation of a example. Find more on Data Distribution Plots in Help Center and File Exchange. Afterwards you can transform the positions: Subtract the center of all points, then replace each point by 1/r (i), while r (i) is the distance to the center. obj_boundaries = bwboundaries(obj_labelmap, 'noholes'); I'd expect to work in the same way. 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. % Convert it to gray scale by taking only the green channel. ( more or less) just. 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. For this example, select a column coordinate. . % different to that found using bwboundaries (latter is perfect), BUT it is the edge contour. MATLAB Language Fundamentals Matrices and Arrays Matrix Indexing. Brett's Pick this week is Freeman chain code, by Nicolas Douillet. plz give a suggestion how i code this to achive my goal or how i will have to run the loop for desired goal.