Please help me with my matlab homework.

6. Open the standard image, 'cameraman.tif with the imread( ) function. Brighten the image by a factor of 2 display the image with a 256-element gray colormap. Darken the image by a factor of 2 and display the image with the same 256-element gray colormap. You may have to ensure that all output values lie in the [0,255]. 7. Form the histograms of the two images created in Problem #6. Display them on the same graph. Again, use the function, [n, v] - hist (x,200)