message: Documentation for standalone thumbnail method
diff: @@ -307,7 +307,18 @@ impl<S: Primitive + Enlargeable> ThumbnailSum<S> {
  }
  }
  -/// Resize the supplied image down to the specific dimensions.
  +/// Resize the supplied image to the specific dimensions.
  +///
  +/// For downscaling, this method uses a fast integer algorithm where each source pixel contributes
  +/// to exactly one target pixel. May give aliasing artifacts if new size is close to old size.
  +///
  +/// In case the current width is smaller than the new width or similar for the height, another
  +/// strategy is used instead. For each pixel in the output, a rectangular region of the input is
  +/// determined, just as previously. But when no input pixel is part of this region, the nearest
  +/// pixels are interpolated instead.
  +///
  +/// For speed reasons, all interpolation is performed linearly over the colour values. It will not
  +/// take the pixel colour spaces into account.
  pub fn thumbnail<I, P, S>(image: &I, new_width: u32, new_height: u32) -> ImageBuffer<P, Vec<S>>
  where
  I: GenericImage<Pixel = P>,
  @@ -417,6 +428,7 @@ where
  )
  }
  +/// Get a thumbnail pixel where the input window encloses at least a vertical pixel.
  fn thumbnail_sample_fraction_horizontal<I, P, S>(
  image: &I,
  left: u32,
  