From Manifold Help:
Surface - Resize
Change the number of pixels in the surface using desired interpolation method.
Choose the interpolation method to be used to re-compute new pixel values as pixels are added or removed to achieve the new size.
Width of the resized surface in pixels.
Height of the resized surface in pixels.
Checking this box will cause any change in Width or Height to automatically update the other parameter so that the width to height proportion is kept the same.
The size readout at the bottom of the dialog gives the size of the surface in kilobytes at the specified width and height.
The Method box chooses the mathematical technique used to interpolate the existing pixels into a greater or lesser number of pixels as the surface changes size. Different methods will at times work better or worse depending on the surface content. Choose from Bicubic, Bilinear and Nearest Neighbor. The default Bicubic method works best with most surfaces.
The screenshot above was created by deleting the least significant digit in the Width and Height values of the original surface, thus reducing the size of the surface by a factor of ten. Note that "size" in this case means the number of pixels used to represent the surface. A georegistered surface will continue to cover the same size on Earth after "resizing". If the surface is made one-tenth the height and width of the original, each individual pixel will simply cover the ground area that one hundred pixels formerly covered.