Then, up$-$sample the images generated before, back to $1024\backslash$times $1024$ pixels. Save

each image to show the effect.

b$.$ Change the gray level of an $8-$bit gray level image $($that has initially $256$ gray levels$)$ to $128,64,32,16,8,4,$ and $2$ gray level images, respectively. Save each image to show the effect. Dont use build in functions in matlab