I often turn PDF sheet music (or my handwritten music scores) into MIDI files so I can edit them. Whenever I have a Beethoven Symphony that I want to redo or something, then I scan the score into my computer as a PDF, convert it to MIDI, and get to work. Who wants to re-input it using a MIDI keyboard - not me!
I tried Photoscore (from Avid/Sibelius). It sucks. Don’t waste your time or money.
I tried Smartscore X. It sucks. Don’t waste your time or money.
In fact, I tried them all. Every single software is buggy, inaccurate, slow, and not what I was looking for.
Enter PDF To Music PRO. So simple and accurate I was laughing: scan, convert to MIDI, export to notation software. Done.
It’s available in both Free and Pro versions.
Note: I’m not getting paid for this. I just wish someone had told me about this product sooner. Over the years it’s the only one of dozens I’ve tried that actually work effortlessly.
Update #1: To clarify: you can take PDF sheet music created from any music program and turn them into MIDI files. What you cannot do is take a handwritten piece of music and scan it, I only work digitally, so this is perfect for me.
Update #2: There is no “free” version of this program. The free version is a trial (although it seemed to last indefinitely in my testing). PDFtoMusic is US $49, whereas PDFtoMusic Pro is US $199 and provides improved recognition and MusicXML export.