storing an image intensity value as an array

how to store intensity values of an image into a matrix via matlab code.i have tried a code which prints the values of intensities using:

for i=1:1.0:455

     for j=1:1.0:306
        val=impixel(img2,i,j);
        disp(val);
    end
end

**Image array is already the intensity matrix..but how can i store it into an array which is user defined variable

Answer 1

[Rick Rosson]

 val = img2(:);

[Durga]

Thank u Sir for helping.