Prefiltering
	Essential for downsampling (decimation) to prevent aliasing MIP-mapping [Williams’83]: 1. build pyramid (but what decimation filter?): – block averaging – Burt & Adelson (5-tap binomial) – 7-tap wavelet-based filter (better) 2.  trilinear interpolation – bilinear within each 2 adjacent levels – linear blend between levels (determined by pixel size)