How to Convert jpg Files to png Files and Save Lots of Space

Gimp

  1. open the file in gimp, "gimp foo.jpg"
  2. index the file with 2 colors, "image > mode > indexed"
  3. set maximum number of colors to 2
  4. file, save as, png, compression level 9, ok
The resulting file should be about 5% of the original file size. for example foo.jpg is here . It is 1.4 meg.
for example foo.png is here . It is 87K
Note that foo.png, has just as much resolution as foo.jpg!