Image resampling by frequency unwrapping

摘要

A method determines at least one image value of a corresponding desired output position of an output image from an input image. An orientation of an edge passing through the output position is determined in a localised region of the input image. A frequency spectrum for the region of the input image is extended. A main frequency band of the edge is aligned in the extended frequency spectrum parallel to a first sampling axis of a grid based on the orientation of the edge. The grid is selected from a set of the input and output grids. The aligned main frequency band is filtered along a second sampling axis of the grid, orthogonal to the first sampling axis, the filter removing frequencies associated with replica bands and maintaining the main frequency band. The image value is determined from the filtered edge at the desired output position.

主权项

1. A method of determining at least one image value of a corresponding desired output position on an output grid of an output image from an input image on an input grid, the method comprising:
(a) determining, in a localised region of the input image, an orientation of an edge passing through the output position; (b) extending a frequency spectrum for the region of the input image; (c) aligning a main frequency band of the edge in the extended frequency spectrum parallel to a first sampling axis of a grid based on the orientation of the edge, wherein the grid is selected from the set of the input and output grids; (d) filtering the aligned main frequency band along a second sampling axis of the grid, orthogonal to the first sampling axis, the filter removing frequencies associated with replica bands and maintaining the main frequency band; (e) determining the image value from the filtered edge at the desired output position; and (f) storing the determined image value as part of the output image.