%--------------------------------------------------------------------
% Function : add_to_image
%
% This function adds the specified face image to the specified 
% background image. The function will ask the user to click on where
% in the background image to add the face image.
%
% Input:
%     source        path of rotated image bmp (face)
%     target        path of backgrouand image bmp to add face to
%     transparency  how transparent should face be when added to 
%                   background. Value should be between 0.0 and 1.0
%
% Output:
%     final_image   returns the source image added to the target image
%                   at the location specified by user
%
% Example:
%     fin_image = add_to_image('face.bmp', 'building.bmp', 0.1);
%
% Info:
%     Henry Lin
%     01/15/2008 for 600.161.01
%--------------------------------------------------------------------

function [final_image] = add_to_image(source, target, transparency); 

inverse = 1 - transparency;

source_image = imread(source);
target_image = imread(target);

size_source = size(source_image)
size_target = size(target_image)

figure;
imagesc(target_image);
axis image

stop = 1;


%--------------------------------------------------------------------
% Get user input for upper-left coord of where to put source image
%--------------------------------------------------------------------
while (stop == 1)

  disp('--------------------------------------------------------------');
  disp('Please select where you would like to put the upper left of the face:');
	origin = uint16(floor(ginput(1)))
   origin = [origin(2) origin(1)];

	if (origin(1) + size_source(1) -1 > size_target(1)) 
  		stop = 1;
		disp('--------------------------------------------------------------');
		disp('ERROR: Face will not fit on target image in y-direction');
		disp('Please try again...');
	elseif (origin(2) + size_source(2) -1 > size_target(2)) 
  		stop = 1;
		disp('--------------------------------------------------------------');
		disp('ERROR: Face will not fit on target image in x-direction');
		disp('Please try again...');
	else 
		stop = 0;
	end
end


%origin = [origin(2) origin(1)];

%--------------------------------------------------------------------
% add the source image to the target image
% use the transparency argument as the transparency
%--------------------------------------------------------------------
for y=origin(1):(origin(1) + size_source(1)-1)
	for x=origin(2):(origin(2) + size_source(2)-1)

	  y_indx = y-origin(1)+1;
	  x_indx = x-origin(2)+1;

	  if(((source_image(y_indx,x_indx,1) >= 240) && (source_image(y_indx,x_indx,2) >= 240) && (source_image(y_indx,x_indx,3) >= 240)) || ((source_image(y_indx,x_indx,1) == 0) && (source_image(y_indx,x_indx,2) == 0) && (source_image(y_indx,x_indx,3) == 0))) 
		 else
			% add to all three color channels
			target_image(y,x,1) = (transparency * target_image(y,x,1)) + (inverse * source_image(y_indx,x_indx,1));	
			target_image(y,x,2) = (transparency * target_image(y,x,2)) + (inverse * source_image(y_indx,x_indx,2));	
			target_image(y,x,3) = (transparency * target_image(y,x,3)) + (inverse * source_image(y_indx,x_indx,3));	
		 end
	end
end

final_image = target_image;

imagesc(final_image);
axis image