Digital Image Compression by Outer Product Expansion
Dianne Prost O’Leary, Bezalel Peleg · IRE Transactions on Communications Systems · 1983
We approximate a digital image as a sum of outer products dxyTwheredis a real number but the vectorsxandyhave elements +1, -1, or 0 only. The expansion gives a least squares approximation. Work is proportional to the number of pixels; reconstruction involves only additions.