I regularly import scans/photos/document camera snapshots from book, papers etc. and they do not always have a good contrast and/or brightness. Which should not be a problem, since a contrast/brightness adjustment is trivial.

However, Notebook does not provide an option to adjust contrast and/or brightness after adding a bitmap.

Which is especially annoying for pictures that are imported directly from the document camera, which not always provide good contrast. Yes, even if using the best possible settings on the camera itself. And even if the settings were not optimal (which can happen), there is no reason not to provide an adjustment option for postprocessing.

You should add a simple contrast/brightness adjustment function for bitmaps.