The code is unreachable.

 segsAll = cell(length(frs),1);

This line of code is unreachable I don't know why. I have supplied the image properly and also tried to display it and it got displayed. But error is still there, something wrong with the if statement.

if true % code

%Define our movie and scale factor
cd demo_people;
addpath(genpath('.'));
frs = 1:201;
movieS = 'ims/%.8d.jpg';
imscale = .6;

%First step; run stylized pose detector on each frame
INIT_DETECT = 0;
if INIT_DETECT
    %First, run our stylized person detector
    segsAll = cell(length(frs),1);
    %for fr = frs,
    for fr = 167 
        fr
        %Read in image, scaling it so torso is roughly 50 pixels long
        imOrig = imread(sprintf(movieS,fr));
        %For this sequence, hard-code in we're looking for some-one
        % walking to the right with a torso 50 pixels high
        im = imresize(imOrig(:,end:-1:1,:),imscale,'bilinear');
        % Because the walking detector involves sampling, may have to 
        % do this multiple times
        % and take best-scoring one
        segs = findWalkingPerson(im);
        %Flip and re-size to regular image
        [segs.x,segs.u] = deal(size(im,2) - segs.x + 1,-segs.u);
        [segs.x,segs.y,segs.len,segs.w] = ...
        deal(segs.x/imscale,segs.y/imscale,segs.len/imscale,segs.w/imscale);
        %Build an appearance model for each limbs and evaluate how 
        % good we are
        modelSegs = buildLimbModelLin({imOrig},{segs});
        %Sum up the fraction of missclassified pixels, downweighting 
        % the upper arm by .5
        segs.cost = [1 .5 1 1 1 1 1 1] * modelSegs.err;
        segsAll{fr} = segs;
    end

      %Take the best scoring one
      costs = repmat(100,length(frs),1);
      for i = 1:length(frs),
          if ~isempty(segsAll{i}),
              costs(i) = segsAll{i}.cost;
          end
      end
      [dummy,fr] = min(costs);

      %Build a quadratic logistic regression model for each limb
      im = imread(sprintf(movieS,fr));
      modelSegs = buildLimbModelQuad({im},segsAll(fr));

      save walkingDetections segsAll modelSegs;
  else
      load walkingDetections;
  end

%Track by detecting with learned appearance model
trackSegs = cell(length(frs),1);
for fr = frs,
  fr
  clf;
  im = imread(sprintf(movieS,fr));
  %Can search over image and different scales if desired
  im = imresize(im,imscale,'bilinear');
  subplot(231);
  imshow(im); title(sprintf('Frame %d',fr));
  %Sample body poses by computing the posterior with the 
  % sum-product algorithm
  [pts,cost] = findGeneralPerson(im,modelSegs);
  subplot(235);
  showPersonPts(size(im),pts);
  title('Posterior');
  %Find the modes in the samples
  trackSegs{fr} = findModePose(pts);
  subplot(236);
  showsegIm(im,trackSegs{fr});
  title('Mode in posterior');
  drawnow;
end

%Show the track
clf;
set(gcf,'doublebuffer','on');
for fr = frs,
  im = imread(sprintf(movieS,fr));
  %Can search over image and different scales if desired
  im = imresize(im,imscale);
  showsegIm(im,trackSegs{fr});
  drawnow;
end
end

[matt dash]

You should edit your question to properly format the code. It is very difficult to read as it is.

Answer 1

[per isakson]

INIT_DETECT is always false, thus the first branch of the if-statement cannot be reached.

[samir]

then how should I use that statement so that the first branch is reached?

Answer 2

[Image Analyst]

Change the code to:

INIT_DETECT = true;
if INIT_DETECT

[Image Analyst]

samir's "Answer" moved here since it shoudl really be a "Comment" to me rather than an independent "Answer" to his original question:

I tried running the code with INIT_DETECT =true. I am getting he following error:

Warning: Escape sequence 'U' is not valid. See 'help sprintf' for valid escape sequences. 
> In baseballDo at 18 
Error using imread (line 366)
Can't open file "C:" for reading;
you may not have read permission.

Error in baseballDo (line 18)
        imOrig = imread(sprintf(movieS,fr));

Note: I changed the path of input image file to my local machine path.

[Image Analyst]

Try this:

% Create full file name of file in the ims subfolder
% of the current folder.
movieS = sprintf('%s/ims/%.8d.jpg', pwd, fr);
% Make sure it exists.  Warn if it does not exist.
if ~exist(movieS, 'file')
    warningMessage = sprintf('Image file not found:\n%s', movieS);
    uiwait(warndlg(warningMessage));
    continue;
end
im = imread(movieS);