function [cm,controlim] = controlroi(imsegm,labelim,nuclei,rim,prm)

msg = ['This is ' upper(mfilename) ' finding control regions'];
disp(msg);

tic
% find possible did cells (NB lower threshold than earlier)
bw = imsegm > prm.detect.level*0.70;

% remove noise objects
bw = bwareaopen(bw,10);

% label and find CM
[faser,L] = bwlabeln(bw);
L
cm = zeros(L,2);
for i = 1 : L
    % this region
    reg = faser == i;
        
    clear c;
    [c(:,1),c(:,2)] = find(reg);

    % center of mass
    cm(i,:) = mean(c,1);
end;
cm = round(cm);
toc;
msg = ['Finding ' int2str(L) ' potential DiD objects'];
disp(msg);

% distance around cells
dist = prm.detect.smallestdistcells;

% label image around the DiD cells not to take these regions
dim = size(labelim);
controlim = ones(dim(1),dim(2),'uint8');
for i = 1 : L
    x = max(1,cm(i,1) - dist):min(dim(1),cm(i,1)+dist);
    y = max(1,cm(i,2) - dist):min(dim(2),cm(i,2)+dist);
    controlim(x,y) = 0;    
end;
close all
% showall(imsegm,controlim)

% all possible positions to use as control image
clear c;
[c(:,1),c(:,2)] = find(controlim);


% order them randonly
n = size(c,1);
v = randperm(n);
c = c(v,:);

% rim coordinates
[rim.c(:,1),rim.c(:,2)] = find(rim.bw);

msg = ['Finding ' int2str(prm.detect.ncontrol) ' objects'];
disp(msg);

ncontrol = 0;
i = 0;
cmcontrol = zeros(prm.detect.ncontrol,2);
while ncontrol < prm.detect.ncontrol
    i = i + 1;
    cmhere = c(i,:);
    x = max(1,cmhere(1)-dist):min(dim(1),cmhere(1)+dist);
    y = max(1,cmhere(2)-dist):min(dim(2),cmhere(2)+dist);
    reg = controlim(x,y);
    
    showall(
    % is there an overlap to a DiD cell image?
    if ~isempty(find(reg,1))
        msg = ['Overlap to DID or earlier object'];
        disp(msg);        
        continue;
    end;
    
    % is it dense enough of cells?     
    imhere = nuclei.bw(x,y);
    [a,n] = bwlabeln(imhere);
    if n < prm.detect.minnumneigh
        msg = ['Too sparse cells'];
        disp(msg);
        continue;
    end;

    % is it far enough from rim?
    d = rim.c - repmat(cmhere.*prm.lowres.h,rim.nc,1);    
    d = d.^2;
    d = sum(d,2);
    d = sqrt(d);   
    if d < prm.detect.smallestdistrim
        msg = ['Too close too rim'];
        disp(msg);
        continue;
    end;

    % label this region as "taken"
    controlim(x,y) = 2;
    
    % and store the coordinates
    ncontrol = ncontrol + 1;
    cmcontrol(ncontrol,:) = cmhere;
    msg = ['Finding control ROI ' int2str(ncontrol)];
    disp(msg);
        
end;
showall(bw,controlim)
controlim = controlim == 2;