make a photo of sheet music black and white, remove grey

[david]

This is something I have been doing for many years.

I find the best solution is to use curves. Move the topmost point to the left until the background is white and move the bottom point too the right until the staves, notes and rests are clear - these are the most important! On well thumbed copies you may have to put up with the odd discoloured mark on the background in order to make sure the notes are readable.

This method has the advantage that it is fast. If you have only a few sheets to print you can of course use more sophisticated methods.