4. Suppose images fixy) and g(xy) have histograms hf and hs. Suppose you form image k(x.y) as the sum of these two images: k(x,y) =f(x,y) + g(x,y). (a) Under what conditions (on images f and g) can you determine the histogram h; of image k in terms of the histograms lif and ig? (That is, under what conditions can you determine In if you are only given hf and g? Hint: this tuurns out to be fairly restrictive.) (b) Explain how you would derive hi in this case