function [xp,yp,calibok]=GetTargetPosition(nmod,im0,U,V,gim)
persistent dist xyi dmin

sizeim0=size(im0);
load(fullfile('TMP',sprintf('%d_params',nmod)),'param');
ngrid=param.grid_size;

nim0=255-im0;
nx=ngrid(1);
ny=ngrid(2);
calibok=0;
ntry=0;
set(gim,'Cdata',im0')

%while ~calibok&&ntry<5
calibok=1;
if 1||isempty(xyi)
    title('Pick up the lower left dot')
    [xo,yo] = ginput(1);
    if isempty(dist)
        title('Pick up a neighboor')
        [xn,yn] = ginput(1);
        dist=abs(xo-xn+1i*(yo-yn));
    end
else
    xo=xyi(1)+U;
    yo=xyi(2)+V;
end
%gini= plot(xo,yo,'sm','MarkerSize',20)

%xo=316;yo=964;
%%
%nx=9;
%ny=9;
[indy,indx]=meshgrid(1:ny,1:nx);

%if isempty(dmin),
dmin=round(0.2*dist);
%end
res=Inf;
conv=1.e-3;
xo=round(xo);
yo=round(yo);
in=-5:5;
xin=in+xo;
yin=in+yo;
try
    sub=nim0(xin,yin);
catch
    calibok=0;
    ntry=ntry+1;
    %        continue
end
thres=0.9*mean(sub(:));
subold=0;
while res>conv
    in=-dmin:dmin;
    xo=round(xo);
    yo=round(yo);
    xin=in+xo;
    yin=in+yo;
    try
        sub=nim0(xin,yin)>thres;
    catch
        calibok=0;
        ntry=ntry+1;
        break
        
    end
    [yin,xin]=meshgrid(in,in);
    dx=xin.*sub;
    dy=yin.*sub;
    
    
    sub=sum(sub(:));
    
    dx=sum(dx(:))/sub;
    dy=sum(dy(:))/sub;
    res=abs(subold-sub)/dmin^2;
    subold=sub;
    dmin=dmin+1;
    xo=xo+dx;
    yo=yo+dy;
    if dmin/round(0.2*dist)>10||dmin/round(0.2*dist)<.1
        calibok=0;
        ntry=ntry+1;
        break
    end
end
in=-round(1.5*dmin):round(1.5*dmin);
xo=round(xo);
yo=round(yo);
%    xin=in+xo;
%    yin=in+yo;
xin=min(max(1,in+xo),size(nim0,1));
yin=min(max(1,in+yo),size(nim0,2));

%thresholding
%sub=nim0(xin,yin);
%in=(-dmin:dmin)+round(1.5*dmin)+1;
%select=0*sub;
%select(in,in)=1;
%thres=0.5*(mean(sub(select==1))+mean(sub(select==0)));
%nim0s=nim0>thres;

%dmin=dmin-1;
lx=dist;
ly=dist;
xx=1;xy=0;
yx=0;yy=1;
dmin=round(1.25*dmin);
conv=0.5;
Xp=xo+(indx-1)*lx;
Yp=yo+(indy-1)*ly;
dXYp=max(indx,indy);
[dXYps,ordre]=sort(dXYp(:));
if calibok
    % figure
    % imagesc(im0)
    % colormap('gray')
    % hold on
    %gini= plot(Xp,Yp,'bo','MarkerSize',10);
    donex=zeros(nx,ny-1);
    doney=zeros(nx-1,ny);
    %          figure
    %          imagesc(nim0)
    %          colormap('gray')
    %          hold on
    for ii=1:length(ordre)
        [ix,iy]=ind2sub([nx,ny],ordre(ii));
        if (ix>1)||(iy>1)
            reso=0;
            res=Inf;
            xo=Xp(1,1)+(ix-1)*lx*xx+(iy-1)*ly*yx;
            yo=Yp(1,1)+(ix-1)*lx*xy+(iy-1)*ly*yy;
            
            
            in=-round(1.5*dmin):round(1.5*dmin);
            xo=round(xo);
            yo=round(yo);
            %    xin=in+xo;
            %    yin=in+yo;
            xin=min(max(1,in+xo),size(nim0,1));
            yin=min(max(1,in+yo),size(nim0,2));
            
%thresholding
% sub=nim0(xin,yin);
%             in=(-dmin:dmin)+round(1.5*dmin)+1;
%             select=0*sub;
%             select(in,in)=1;
%             thres=0.5*(mean(sub(select==1))+mean(sub(select==0)));
            
            
            
            
            %         plot(yoo,xoo,'w+','MarkerSize',10,'LineWidth',2)
            %         plot(yo,xo,'rx','MarkerSize',10,'LineWidth',2)
            iter=0;
            while (res>conv)&&(abs(res-reso)>0)&&(iter<100)
                reso=res;
                in=-dmin:dmin;
                xo=round(xo);
                yo=round(yo);
                xin=min(max(1,in+xo),size(nim0,1));
                yin=min(max(1,in+yo),size(nim0,2));
                
                %thresholding
                %sub=nim0(xin,yin)>thres;
                %kmeans
                sub=nim0(xin,yin);
                [indc,vals]=kmeans(sub(:)',2);
                [~,imax]=max(vals);
                sub=reshape(indc==imax,size(sub));
                sub(xin==1)=0;sub(xin==size(nim0,1))=0;
                sub(yin==1)=0;sub(yin==size(nim0,2))=0;
                [yin,xin]=meshgrid(in,in);
                dx=xin.*sub;
                dy=yin.*sub;
                
                
                sub=sum(sub(:));
                
                dx=sum(dx(:))/sub;
                dy=sum(dy(:))/sub;
                res=abs(dx+1i*dy);
                xo=xo+dx;
                yo=yo+dy;
                iter=iter+1;
                %             if iter>5
                %                 keyboard
                %             end
                %             plot(yo,xo,'bx','MarkerSize',10)
            end
            %        pause
            %            plot(yo,xo,'bo','MarkerSize',10)
            %              pause(.1)
            Xp(ix,iy)=xo;
            Yp(ix,iy)=yo;
        end
        if (ix>1)||(iy>1)
            donex(ix,max(1,iy-1))=1;
            doney(max(1,ix-1),iy)=1;
        end
        if any(donex(:))
            xx=diff(Xp,1,1);
            xy=diff(Yp,1,1);
            yx=diff(Xp,1,2);
            yy=diff(Yp,1,2);
            
            xx=mean(xx(doney>0));
            xy=mean(xy(doney>0));
            yx=mean(yx(donex>0));
            yy=mean(yy(donex>0));
            lx=abs(xx+1i*xy);
            xx=xx/lx;
            xy=xy/lx;
            ly=abs(yx+1i*yy);
            yx=yx/ly;
            yy=yy/ly;
        end
    end
    ntry=ntry+1;
end
xp=Xp(:)-0.5*(sizeim0(1)-1);
yp=Yp(:)-0.5*(sizeim0(2)-1);
if isempty(xyi)
    xyi=[Xp(1),Yp(1)];
end
if any(isnan(xp))||any(isnan(yp))
    calibok=0;
end
if ~calibok
    title('Detected dots: failure ! Image will be ignored....')
    display('Calibration failed')
    gp=plot(Xp,Yp,'rx','MarkerSize',10,'LineWidth',2);
else
    title('Detected dots')
    
    gp=plot(Xp,Yp,'gx','MarkerSize',10,'LineWidth',2);
    
end


pause(1)
delete(gp)
try delete(gini),catch ;end
end