Patent ID: 7672528

Claim:
A method of processing a digital image with a computer having a digital image processing function to form an image pyramid having a first to a Nth number of pyramid image levels from a luminance image obtained from the digital image, the Nth number corresponding to a predetermined number of pyramid image levels or a number reached when a predetermined condition is met, the method comprising the steps of: a) generating a first level base image comprising pixel values at pixel locations arranged in rows and columns based on an initial level base image, which is the luminance image obtained from the digital image, the first level base image having a smaller resolution than the initial level base image; b) generating a next level base image by: determining sample locations for the next level base image in the pyramid based solely on the previous level base image without adding a border around the previous level base image, such that the sample locations are arranged in a regular pattern and the sample locations both span an entire range of and beyond the pixel locations of the previous level base image but with the next level base image having a smaller resolution than the previous level base level image; determining the pixel values of the next level base image by interpolating the pixel values of the previous level base image using an interpolation filter at the determined sample locations, wherein the interpolation filter is configured to interpolate between pixel values nearby the determined sample locations, and wherein mirroring is used for sample locations within the determined sample locations (1) whose pixel values are to be interpolated and (2) whose locations are outside of the range of the pixel locations of the previous level base image; c) generating a subsequent level base image to an Nth level base image by repeating step b) until the Nth number of pyramid image levels are generated.