How to separate line art from the white in GIMP?

I'm trying to clean and re size line art in gimp but am having too low of quality results.. help?

• I have drawn some manga styled line art and wish to clean and resize it. There are many tutorials on this subject, but few that deal with the quality loss during resize. I am ...show more

• Answer:

  try to keep resolution high at 300 or above 144, to keep pixel details in tacked and better for printing, if images are low at 72ppi, and you make smaller, then pixels make image very poor to edit with, 4x4" inches is moderate to edit with could double size and edit lines, save as xcf gimp file, and when done resize to use jpg/ png online, check image size properties, print size, canvas size, and resolution, and options for resample or ratio when resizing, http://www.espressographics.com/text/imagesize.html http://orderartwork.com/Photo_Services_Premium_Add_Photo_Resolution.htm ..