The only real choices with any image expansion is either blur the enlargement, create a jagged, grainy enlargment, or use .svg files to preserve the color data at every level. Sadly there aren't many public domain .svg files that really let you see the magnification in action, so this is really the best I can do as an example of a well known public domain image.
 "Magnify Tutorial"){kind=icon}
The only real choices with any image expansion is either blur the enlargement, create a jagged, grainy enlargment, or use .svg files to preserve the color data at every level. Sadly there aren't many public domain .svg files that really let you see the magnification in action, so this is really the best I can do as an example of a well known public domain image.