Doug Spencer writes:

Being an electronic format, you can convert them to whatever you want.
Imagemagick worked very well for me to convert them to compressed JPG
or PNG files and store the whole USA on a 1GB memory card to view on a
handheld. It was lot more compact than carrying and unfolding a bunch
of paper charts.

You can't convert from scans to PDF, though. PDF is a lot cleaner.

Airport diagrams and plates are now in PDF format, but the charts are
not. I can see a number of technical problems with converting them,
beyond the labor required to rebuild them from scratch.

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