how can I speed up this function ?

I'm working on a steganography project . i wrote a simple lsb function that hides one letter of a message in one pixel of an image but it's too slow because of the loops and dec2binvec function(according to profile). i need to make it run faster.any help?

function [red,blue,green] = encrypt(red,blue,green,data)

data = dec2binvec(data,8);
%encrypting the blue bits
i = 1;
while( i <=3)
   if(data(i) ~= bitget(blue,i))
if(data(i) == 0)
blue = bitset(blue,i,0);
else
blue = bitset(blue,i,1);
end
   end
   i = i+1;
end

     %encrypting the green bits
i = 1;
t=4;
while( i <=3 && t <= 6)
     if(data(t) ~= bitget(green,i))
if(data(t) == 0)
green = bitset(green,i,0);
else
green = bitset(green,i,1);
end
     end
  i = i+1;
  t = t+1;
end

%encrypting the red bits

i = 1;
t=7;
while( i <=2 && t <= 8)
   if(data(t) ~= bitget(red,i))
if(data(t) == 0)
red = bitset(red,i,0);
else
red = bitset(red,i,1);
end
   end
i = i+1;
t = t+1;
end
return;