function lab1_ex6(input_image_path, output_folder_abspath, row_number, varargin)
% Basic Image Processing and Analysis, 2016.
% solution function for lab1 / exercise6
    
    input_img = imread(input_image_path);
    if size(input_img, 3)>1
        input_img = rgb2gray(input_img);
    end
    
    fighandler = figure;
    subplot(2, 1, 1);
    imshow(input_img);
    subplot(2, 1, 2);
    plot(input_img(row_number, :), 'r.', 'MarkerSize', 12);
    titlestr = strcat('row number (red): ', num2str(row_number));
    if ~isempty(varargin)
        hold on;
        plot(input_img(varargin{1}, :), 'b.', 'MarkerSize', 12);
        hold off;
        titlestr = strcat(titlestr, ', row number (blue): ', num2str(varargin{1}));
    end
    title(titlestr, 'FontSize', 14);
    xlabel('column number', 'FontSize', 12, 'FontWeight', 'bold');
    ylabel('pixel intensity value', 'FontSize', 12, 'FontWeight', 'bold');
    
    [pathstr, name, ext] = fileparts(input_image_path);
    if exist(output_folder_abspath, 'dir')~=7
        mkdir(output_folder_abspath);
    end
    out_file_name = strcat(output_folder_abspath, name, '_pixelIntensityCurves', ext);
    saveas(fighandler, out_file_name);
    
end