Comparing fonts to music is fun, but the example you give, comparing filtering or basic manipulation across these media is the least interesting aspect in my opinion. I think these may be less boring...
"Tracing" - which is kind of like buying (or photocopying) the sheet music, and recording your own version of the song. Requires more skill than filtering or tweaking but the results are almost always worse than the original.
"Playing by ear" - knowing the basic tune, and playing your own version, bringing your own voice to the recording. Depending on your skill you might improve upon the original. In the font world most people wouldn't look down on this practice.
Of course where comparisons fall down is the legal protection afforded to music and the power of the recording industry - both of which far exceed that afforded to fonts.