I have 180 pages looking like my sample. The "noise" is in text end drawings, but the problem for me is the text, since text recognition having problem with danish letters, and the placing of the chords between the lines does not seams lineup either - I´m looking at 10-15 minuts of manuel cleaning the photos that's 3-4 days work - or I could manuel type in everything but I would properly just end up taking longer...
I mad it as PDF with 30 sheets pr file, and im having no problem importing and adding a mask layer and export it again - so if there is a way to reduce the noise, I now its still gonna be a bit of a job - but if I could remove every smal cluster (like 10-30px spots) of "non white" pixel, I would be a break through.
I´m using this project to learn the "layer" skill again (was using photoshop for years back in 2000-2010) of non destructive work flow and editing, so I welcome the work, but there must bee a smart filter function I can't figure.
And btw, th paper is 30 years old and have been in use almost every week since, so I can't get the scan better then this 300dpi bw file
Hope you have som ideas?