Noisy Bit-Planes

When we create bit planes of any image then some of them appears near to the original image & some of them are pure dark .So these bit planes are noisy .To detecting noisy bit plane we need to compare each pixel to its three adjacent pixels .If  we talk about pixel(x,y) then we need to compare it to the pixel(x-1,y),pixel(x-1,y-1)& pixel(x-1,y-1) .If pixel(x,y) is same as the at least two of them then this pixel is not noisy.A noisy noisy bit plane will have 49 to 51% pixels that are noise.