Density-dependent sharpening

Abstract

A sharpening filter is disclosed for performing density-dependent sharpening on digital images. In one embodiment, a digital image to be sharpened is decomposed into a plurality of high-pass versions of the image at different resolutions. These high-pass images are gained at each resolution and recombined with the original image to produce a sharpened version of the image. The gains that are applied at each resolution are density-dependent. As a result, the effects of density-dependent blurring are counteracted, such that the sharpness of the final printed image is independent of the print density. Techniques are disclosed for performing such density-dependent sharpening with a high degree of computational efficiency.

Description

[0001] Cross References to Related Applications [0002] This application is related to US Patent No. 6801233B2, commonly entitled "Thermal Imaging System," which is incorporated herein by reference. technical field [0003] The present invention relates to digital image processing, and more particularly, to techniques for sharpening digital images. Background technique [0004] The above-cited patent entitled "Thermal Imaging System" discloses a print medium having multiple color-forming layers. Referring to FIG. 1 , there is shown a schematic diagram of the structure of one embodiment of a medium 100 disclosed in the above-referenced patent application. Two of the colorants, yellow and magenta (the two colorants are shown as one layer for purposes of illustration, but they generally exist in separate layers) 102a, are near the top of the media 100, while the third The first colorant, cyan 102c, is separated from the first two colorants by a relatively thick matrix 102b w...

AI Technical Summary

Problems solved by technology

As a result, edges printed at low density are not as sharp as equivalent edges printed at high density

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