 Leptonica provides many simple and relatively efficient
   implementations of image scaling.  Some of them are listed here;
   for the full set see the web page and the source code.

   Grayscale and color images are scaled using:
      - sampling
      - lowpass filtering followed by sampling,
      - area mapping
      - linear interpolation

   Scaling operations with antialiased sampling, area mapping,
   and linear interpolation are limited to 2, 4 and 8 bpp gray,
   24 bpp full RGB color, and 2, 4 an