Yik-Hing Fung

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Multiscale error diffusion (MED) is superior to conventional error diffusion algorithms as it can eliminate directional hysteresis completely and possesses a good blue noise characteristic. However, due to its filter design, it is not suitable for systems with poor isolated dot generation and instable dot gain. In this paper, we propose a MED algorithm to(More)
Multiscale error diffusion (MED) is superior to conventional error diffusion algorithms as it can eliminate directional hys-teresis completely. However, due to its frame-oriented processing nature, the computational complexity is comparatively high. Furthermore , though theoretically MED can remove directional hysteresis by eliminating predefined scanning(More)
A good halftoning output should bear a blue noise characteristic contributed by isotropically-distributed isolated dots. Multiscale error diffusion (MED) algorithms try to achieve this by exploiting radially symmetric and noncausal error diffusion filters to guarantee spatial homogeneity. In this brief, an optimized diffusion filter is suggested to make the(More)
—To efficiently render halftone images for various printers and displays that support different resolutions, it is desirable that all halftoning results can be produced at a time, and all of them can be embedded in a single full-scale halftone image such that a simple down-sampling process can extract images of suitable resolutions from it if necessary.(More)
This paper studies the restoration of images which are color-quantized with error diffusion. Though there are many reported algorithms proposed for restoring noisy blurred color images and inverse halftoning, restoration of color-quantized images is rarely addressed in the literature especially when the images are color-quantized with halftoning. Direct(More)
The advance in printing technology makes multilevel halftoning become important as printers can now print inks of different intensities. This letter presents a multilevel halftoning algorithm that is based on multiscale error diffusion. This algorithm takes care of the constrained pixels before handling the unconstrained pixels and diffuses errors with a(More)
This paper studies the restoration of color-quantized images. Restoration of color-quantized images is rarely addressed in literature, and direct applications of existing restoration techniques are generally inadequate to deal with this problem. In this paper, we propose a restoration algorithm for restoring color-quantized images. This algorithm makes good(More)