Error using kalman filter for motion tracking.

%%Code in the Bold, & comments in normal font

clear all; close all; clc % Read video into MATLAB using VideoReader video = VideoReader('C:\Users\yashsavi\Desktop\input.avi'); %'n' for calculating the number of frames in the video file n = length(video); % Calculate the background image by averaging the first 10 images temp = zeros(size(video(1).cdata)); [M,N] = size(temp(:,:,1)); for i = 1:10 temp = double(video(i).cdata) + temp; end imbkg = temp/10; % Initialization step for Kalman Filter centroidx = zeros(n,1); centroidy = zeros(n,1); predicted = zeros(n,4); actual = zeros(n,4); % % Initialize the Kalman filter parameters % R - measurement noise, % H - transform from measure to state % Q - system noise, % P - the status covarince matrix

% A - state transform matrix

R=[[0.2845,0.0045]',[0.0045,0.0455]']; H=[[1,0]',[0,1]',[0,0]',[0,0]']; Q=0.01*eye(4); P = 100*eye(4); dt=1; A=[[1,0,0,0]',[0,1,0,0]',[dt,0,1,0]',[0,dt,0,1]']; % loop over all image frames in the video kfinit = 0; th = 38; for i=1:n imshow(video(i).cdata); hold on imcurrent = double(video(i).cdata);

% Calculate the difference image to extract pixels with more than 40(threshold) change
diffimg = zeros(M,N); 
diffimg = (abs(imcurrent(:,:,1)-imbkg(:,:,1))>th) ...
    | (abs(imcurrent(:,:,2)-imbkg(:,:,2))>th) ...
    | (abs(imcurrent(:,:,3)-imbkg(:,:,3))>th); 
% Label the image and mark
labelimg = bwlabel(diffimg,4);
markimg = regionprops(labelimg,['basic']);
[MM,NN] = size(markimg); 
% Do bubble sort (large to small) on regions in case there are more than 1
% The largest region is the object (1st one)
for nn = 1:MM
    if markimg(nn).Area > markimg(1).Area
        tmp = markimg(1);
        markimg(1)= markimg(nn);
        markimg(nn)= tmp;
    end
end 
% Get the upper-left corner, the measurement centroid and bounding window size
bb = markimg(1).BoundingBox;
xcorner = bb(1);
ycorner = bb(2);
xwidth = bb(3);
ywidth = bb(4);
cc = markimg(1).Centroid;
centroidx(i)= cc(1);
centroidy(i)= cc(2); 
% Plot the rectangle of background subtraction algorithm -- blue
hold on
rectangle('Position',[xcorner ycorner xwidth ywidth],'EdgeColor','b');
hold on
plot(centroidx(i),centroidy(i), 'bx'); 
% Kalman window size
kalmanx = centroidx(i)- xcorner;
kalmany = centroidy(i)- ycorner; 
if kfinit == 0
    % Initialize the predicted centroid and volocity
    predicted =[centroidx(i),centroidy(i),0,0]' ;
else
    % Use the former state to predict the new centroid and volocity
    predicted = A*actual(i-1,:)';
end
kfinit = 1; 
Ppre = A*P*A' + Q;
K = Ppre*H'/(H*Ppre*H'+R);
actual(i,:) = (predicted + K*([centroidx(i),centroidy(i)]' - H*predicted))';
P = (eye(4)-K*H)*Ppre; 
% Plot the tracking rectangle after Kalman filtering -- red
hold on
rectangle('Position',[(actual(i,1)-kalmanx) (actual(i,2)-kalmany) xwidth ywidth], 'EdgeColor', 'r','LineWidth',1.5);
hold on
plot(actual(i,1),actual(i,2), 'rx','LineWidth',1.5);
drawnow;
end
%end of the code

[Yashsavi]

Error encountered: No appropriate method, property, or field cdata for class VideoReader.

Error in kalman (line 11) temp = zeros(size(video(1).cdata));