function [ pixelVector ] = guardImage( image, mask, maskNumber)

%GUARDIMAGE applies a logical mask to an image and returns a

%one-dimensional array of the valid pixels

%   param maskNumber

%       maskNumber indicates what value in the image you are looking to

%       guard on. For example, if you want to guard on the foreground you

%       can provide a 1. If you want to get the background, then provide a

%       0. The default value is for the foreground, or a 1.

    %%Pre-process

    %check if a maskNumber is provided

    if ~exist('maskNumber','var')

        maskNumber=1;

    end

    %make an array of zeros

    pixelVector = zeros;

    %get size of image

    sizeImage = size(image);

    %array pos

    x = 1;

    %% create pixel vector from the mask

    for i=1:sizeImage(1)

       for j=1:sizeImage(2)

           if(mask(i,j) == maskNumber)

               %if part of the mask, then add to pixel vector

               pixelVector(x) = image(i,j);

               %increment

               x = x + 1;

           end

       end

    end