Patent ID: 7382489

Claim:
A method for computing the function value of an input node based on function values of known nodes within a multiple raster content, where multiple input images, some or all of which may be sub-sampled, are merged according to a given rule, to form an output image, the method comprising the operations for each input image individually, and comprising the steps of: (a) forming a database of known nodes and corresponding known node function values, the known nodes being located such that a distance between any two adjacent known nodes is an integer power-of-two number; (b) searching from the database of known nodes for a first node such that the input node is located between the first node and a second node adjacent to the first node, the first and second nodes having a first node function value and a second node function value, respectively; (c) computing the difference d between the input node and the first node; (d) shifting d to the right by k positions, k being the logarithm in base 2 of the distance between the first node and the second node; (e) computing the function value of the input node by combining the first node function value with the product of the shifted d and the difference between the second node function value and the first node function value; (f) generating a first lookup table that includes node indices corresponding to the known nodes and the corresponding node function values; (g) computing inter-node exponents as needed; and (h) loading the first lookup table into the database.