MATLAB: How to solve this – Undefined operator ‘.^’ for input arguments of type ‘struct’.

Question

clc;
close all;
clear all;
      Im = imread('B1_16.tif');
      I=rgb2gray(Im);
      I=adapthisteq(I);
      [row col]=size(I)
      double(I);
      figure
      imshow(I)
       % DoG filter (to improve the edge)
      sigma = 4;
  gauss1 = fspecial('gaussian', round([10*sigma 10*sigma]), sigma);
  sigma = 0.1;
  gauss2 = fspecial('gaussian', round([10*sigma 10*sigma]), sigma);
  blur1 = imfilter(I, gauss1, 'replicate', 'same');
  blur2 = imfilter(I, gauss2, 'replicate', 'same');
  dog = blur1 - blur2;
  figure
  imshow(dog)
      str = 'Click to select initial contour location. Double-click to confirm and proceed.';
      title(str,'Color','b','FontSize',12);
      disp(sprintf('\nNote: Click close to object boundaries for more accurate result.'));
      % Select region interactively
      mask = roipoly;
      figure, imshow(mask)
      title('Initial MASK');
      % Segment the image using active contours
      maxIterations = 1; % More iterations may be needed to get accurate segmentation. 
      bw = activecontour(I, mask, maxIterations, 'Chan-Vese');
      % Display segmented image
      figure, imshow(bw)
      title('Segmented Image');
      % find the features of the segmented area using function
      g=regionprops(bw,'all')
      % finding the area of the white area segmented from the previous images
      % area is the number of white pixel in the image
      numofpixels=sum(bw(:))% correct (num of pixels indicates the area of the segmented image)
      % numofpixels1=sum(I(:)) just to confirm that the algorithm used is
      % correct
      % measure the perimeter
      Perimeter=regionprops(bw,'perimeter')
      % determine the circularities 
      Circularities=Perimeter.^2/(4*pi*numofpixels)
      %perimeter
      pm=bwperim(bw,8)
      red=Im(:,:,1);
      green=Im(:,:,2);
      blue=Im(:,:,3);
      red(pm)=255;
      green(pm)=255;
      blue(pm)=0;
      out=cat(3,red,green,blue);
      figure 
      imshow(pm)
      figure 
      imshow(out)

Answer 1

Change

Perimeter=regionprops(bw,'perimeter')

to

rinfo = regionprops(bw,'perimeter');
Perimeter = [rinfo.Perimeter];