There's a .pdf file I need to make darker. It's sheet music 
The lines are very light, making the music hard to read. I need them to be as dark as possible, or as black as possible.
Could anyone give me some advice on how I could do this? I'd really appreciate it!
Thanks so much!

The lines are very light, making the music hard to read. I need them to be as dark as possible, or as black as possible.
Could anyone give me some advice on how I could do this? I'd really appreciate it!
Thanks so much!