createROIMask.m

function [fgo, roi, bw_mask1] = createROIMask(fg, bg, roitype)
%   has 3 options - rectangular, elliptical and freeform. 
    %check roitype
    if(roitype == 1)
        roi = drawrectangle('Label', 'ROI', 'color', [1 0 0]);
    elseif(roitype == 2)
        roi = drawellipse('Label', 'ROI', 'color', [1 0 0]);
    else
        roi = drawfreehand('Label', 'ROI', 'color', [1 0 0]);
    end
    %to handle difference in sizes of images
    %create mask from the selected ROI 
    bw_mask = createMask(roi);
    [rb, cb, bch] = size(bg);
    [rf, cf, fch] = size(fg);
    %resize/ pad fg based on its original size.  
    if(rf*cf>rb*cb)
        fgo=upscale(fg, [rb,cb,bch]);
        bw_mask1 = upscale(bw_mask, [rb,cb]);
    elseif(rf*cf<rb*cb)
        fgo = zeros(rb,cb,bch);
        bw_mask1 = zeros(rb,cb);
        if rf<rb && cf<cb
            % center the smaller fg and its mask by zero padding to bg size 
            fgo(floor(rb/2)+(1:rf)-floor(rf/2), floor(cb/2)+(1:cf)-floor (cf/2),:) = fg;
            bw_mask1(floor(rb/2)+(1:rf)-floor(rf/2), floor(cb/2)+(1:cf)-floor(cf/2)) = bw_mask;
        elseif rf<rb && cf>cb
            fac = 1-((cf-cb)/cb);
            fg = downscale(fg,fac);
            bw_mask = downscale(bw_mask,fac);
            [rf, cf, fch] = size(fg);
            % center the smaller fg and its mask by zero padding to bg size 
            fgo(floor(rb/2)+(1:rf)-floor(rf/2), floor(cb/2)+(1:cf)-floor (cf/2),:) = fg;
            bw_mask1(floor(rb/2)+(1:rf)-floor(rf/2), floor(cb/2)+(1:cf)-  floor(cf/2)) = bw_mask;
        elseif rf>rb && cf<cb
            fac = 1-((rf-rb)/rb);
            fg = downscale(fg,fac);
            bw_mask = downscale(bw_mask,fac);
            [rf, cf, fch] = size(fg);
            % center the smaller fg and its mask by zero padding to bg size 
            fgo(floor(rb/2)+(1:rf)-floor(rf/2), floor(cb/2)+(1:cf)-floor (cf/2),:) = fg;
            bw_mask1(floor(rb/2)+(1:rf)-floor(rf/2), floor(cb/2)+(1:cf)- floor(cf/2)) = bw_mask;
        end
    else
        fgo = fg;
        bw_mask1 = bw_mask;
    end
end