I would love to make it so you could select an area of the histogram, but before you right click and select copy you could hold down a key like CTLR and click single cells that you do not want. Then you could right click and select the copy function.
That way we could easily apply only the cells we choose but we still have the great benefit of selecting an area minimizes the math and manually doing it on a cell by cell basis to adjust it properly.
Hope that makes sense. Any HPTuners Rules!