Error when reading data

I am having an issue when obtaining some image data using the image processing toolbox. When I run the program using one set of images the program works fine. When I use a different set it spits out an error.

Too many outputs requested.  Most likely cause is missing [] around
left hand side that has a comma separated list expansion.
Error in ImFunc (line 51)
    bb = measurements.BoundingBox;
Error in ImageProcessing (line 18)
[Theta,centroid] = ImFunc(Length,ImNum,FoldLoc,First);

For the record, when I add the [] the program then gets stuck. Here is the code I am using:

clc;    % Clear the command window.
close all;  % Close all figures (except those of imtool.)
clear;  % Erase all existing variables.
workspace;  % Make sure the workspace panel is showing.

% Used to calibrate pixel length.
Length = input('Enter length of strip (in inches): ');

% Used to determine what images to look at
ImNum = input('Enter total images taken: ');
First = input('Enter the first image used: ');

%This is where the program looks for the images.
% Example: K:\Matlab_Research\3B_01\3B_01
FoldLoc = input('Enter the location of the file folder: ','s');

% Defined function
[Theta,centroid] = ImFunc(Length,ImNum,FoldLoc,First);

% Use these variables to plot the x and y locations
x = centroid(:,1);
y = centroid(:,2);

% Use this to plot against Theta
z = First:ImNum;

subplot(2,1,1), plot(x,y)
subplot(2,1,2), plot(z,Theta)

And the function can be seen below:

function [Theta,centroid] = ImFunc(Length,ImNum,FoldLoc,First)

% Pixel per inch sum
PPIS = 0;

for i = First:ImNum

      % Detemine which image to use.
      if i < 10
          Imagenumber = sprintf('B0000%d.jpg',i);
      elseif i < 100
          Imagenumber = sprintf('B000%d.jpg',i);
      elseif i < 1000
          Imagenumber = sprintf('B00%d.jpg',i);
      elseif i < 10000
          Imagenumber = sprintf('B00%d.jpg',i);
      else
          Imagenumber = sprintf('B0%d.jpg',i);
      end

      % Read in a standard MATLAB gray scale demo image.
      folder = FoldLoc;
      baseFileName = Imagenumber;
      % Get the full filename, with path prepended.
      fullFileName = fullfile(folder, baseFileName);
      % Check if file exists.
      if ~exist(fullFileName, 'file')
          % File doesn't exist -- didn't find it there.  Check the search path for it.
          fullFileName = baseFileName; % No path this time.
          if ~exist(fullFileName, 'file')
              % Still didn't find it.  Alert user.
              errorMessage = sprintf('Error: %s does not exist in the search path folders.', fullFileName);
              uiwait(warndlg(errorMessage));
              return;
          end
      end
      grayImage = imread(fullFileName);
      % Crop away tick marks, colorbar, etc..
      grayImage = rgb2gray(imcrop(grayImage, [1 1 725 400]));

      % Get the binary image
      % Use an algorithm to find the threshold.
      binaryImage = grayImage > 110;

      % Smooth it out some and clean it up.
      binaryImageCent = bwareaopen(binaryImage, 80); 

      labeledImage = bwlabel(binaryImageCent);
      measurements = regionprops(labeledImage, 'all');
      % Crop it to the bounding box.
      bb = measurements.BoundingBox;

      % Crop the image.
      binaryImage = imcrop(binaryImageCent, bb);

      % Skeletonize the image.
      skeleton = bwmorph(binaryImage, 'skel', 'inf');

      % Find the endpoints of the skeleton.
      skeleton = bwmorph(skeleton, 'endpoints');

      % Get the coordinates of all endpoints
      [rows cols] = find(skeleton);
      % Find the two that are farthest apart
      maxDistance = -1;
      for k1 = 1 : length(rows)
          row1 = rows(k1);
          col1 = cols(k1);
          for k2 = 1 : length(rows)
              row2 = rows(k2);
              col2 = cols(k2);
              distance = sqrt((row1-row2)^2 + (col1-col2)^2);
              if distance > maxDistance
                  maxDistance = distance;

                  % Finding x and y component distances
                  y = abs(row2-row1);
                  x = abs(col2-col1);
              end
          end
      end

      % Angle from horizontal
      Thet = atan(y/x)*180/pi;

      % Ensure Theta values correspond to image number
      Theta(i + 1 - First) = Thet;

      % Determine pixels per inch
      PPI = maxDistance/Length;

      %Find the center location
      measurements = regionprops(binaryImageCent, 'Centroid');
      cent = measurements(1).Centroid;

      % Convert pixel location to actual inch location
      % Ensure centroid values correspond to the image number
      centroid(i + 1 - First,:) = cent/PPI;

      % Find every PPI value
      PPIS = PPI + PPIS;

end

% Average the PPI values
PPIA = PPIS/(ImNum - First);

% Find actual size of image
ImageSize = size(grayImage);
height = ImageSize(1,1)/PPIA;
width = ImageSize(1,2)/PPIA;

% Convert the center locations to reflect the actual image    
centroid(:,2) = height - centroid(:,2);
centroid(:,1) = width - centroid(:,1);

Ideas? If you need more info let me know. In the working data I am processing about 400 images. In the nonworking data I am processing 250.

Answer 1

[Walter Roberson]

If more than one region is found in the bwlabel, then the regionprops is going to return a structure array, and then measurements.BoundingBox would be attempting to expand a structure array, leading to the error.

Answer 2

[Coulton]

Ah that makes sense. Let me look into it. Thanks!

Answer 3

[Salitha Kaveendra Nanayakkara]

Facing same problem.Any solutions?

[Walter Roberson]

Somewhere in your code you have a line similar to

A = B.C;

but B is a non-scalar array. You need to either track down why B is non-scalar when you expect it to be scalar, or else you need to use one of

A = {B.C};

or

A = {};
[A{1:length(B)}] = B.C;

In some cases you might be able to use

A = vertcat(B.C);

This reply is general because you asked a general question with no code for us to examine.