Mom asked me to scan in a bunch of photos for her previously, and I scanned them in as PNG files; namely because most any software package can read them, and they don't throw away any of the photo's color information. However, it seems most mini photo labs (where Mom is trying to get these printed; e.g. at a Walgreens) don't have the capability to read PNGs (a fact that blows my mind). If I were to do this myself, I'd probably fire up Bridge or Lightroom and have that software do the job for me, but Mom doesn't have licenses for these expensive software packages.
Simple search results in either online conversion tools (which she cannot practically use because her internet is too slow to comfortably upload multi megabyte PNGs), or.... "hokey" image conversion tools that all seem to want to charge $20 for the privilege. I could send her to something like the GIMP but that's an insanely complicated piece of software I'm not sure she'll be comfortable using.
What should I tell her to do? (I have to explain it over the phone)