plus Integers can only be combined with integers of the same class, or scalar doubles.!!!

hello sir. when i run this particular piece of i code i get error. I donot know what is the problem here.can anyon find my mistake and correct me

     [length width] = size(I_out);
for i = 1:1:length
      for j = 1:1:width
       if (I_out(i,j) == WHITE)
      I_hybrid(i,j) = I_hybrid(i,j) + [0.25 0 0]; ///error in this line
      end
end

[Walter Roberson]

What is the intent? Is the intent to take a value that is an integer in the range 0 to 255, and add 1/4 to it, resulting in (for example) 92.25 from 92? Or is the intent to take a value that is a floating point number in the range 0 to 1, and add 1/4 to it, such as taking (92/255) to (92.25/255) ?