Clustered-minority-pixel error diffusion

Li, Pingshan; Allebach, Jan P.

doi:10.1364/josaa.21.001148

Cited by 10 publications

(2 citation statements)

References 8 publications

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“…The input gray levels directly corresponds to image levels, and they will all be directly mapped to desired values Many input gray levels will receive very little change from this TRC Allebach [18] modify the error diffusion threshold based on the output of previous locations. This dependence encourages the output at the current location to be the same as the output of those previous locations.…”

Section: Review Of Standard Error Diffusionmentioning

confidence: 99%

Rank-ordered error diffusion: method and applications

Loce

2007

SPIE Proceedings

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We present a specialized form of error diffusion that addresses certain long-standing problems associated with operating on images possessing halftone structure as well as other images with local high contrast. For instance, when rendering an image to printable form via quantization reduction, image quality defects often result if that image is a scanned halftone. Rendering such an image via conventional error diffusion typically produces fragmented dots, which can appear grainy and be unstable in printed density. Rendering by simple thresholding or rehalftoning often produces moiré, and descreening blurs the image. Another difficulty arises in printers that utilize a binary image path, where an image is rasterized directly to halftone form. In that form it is very difficult to perform basic image processing operations such as applying a digital tone reproduction curve. The image processing operator introduced in this paper, rank-order error diffusion (ROED), has been developed to address these problems. ROED utilizes brightness ranking of pixels within a diffusion mask to diffuse quantization error at a pixel. This approach to diffusion results in an imagestructure-adaptive quantization with many useful properties. The present paper describes the basic methodology of ROED as well as several applications. Downloaded From: http://proceedings.spiedigitallibrary.org/ on 06/23/2016 Terms of Use: http://spiedigitallibrary.org/ss/TermsOfUse.aspx SPIE-IS&T/ Vol. 6493 64931A-2 Downloaded From: http://proceedings.spiedigitallibrary.org/ on 06/23/2016 Terms of Use: http://spiedigitallibrary.org/ss/TermsOfUse.aspx SPIE-IS&T/ Vol. 6493 64931A-3 Downloaded From: http://proceedings.spiedigitallibrary.org/ on 06/23/2016 Terms of Use: http://spiedigitallibrary.org/ss/TermsOfUse.aspx SPIE-IS&T/ Vol. 6493 64931A-10 Downloaded From: http://proceedings.spiedigitallibrary.org/ on 06/23/2016 Terms of Use: http://spiedigitallibrary.org/ss/TermsOfUse.aspx

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Section: Review Of Standard Error Diffusionmentioning

confidence: 99%

Rank-ordered error diffusion: method and applications

Loce

2007

SPIE Proceedings

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“…Li and Allebach used Levien's output-dependent feedback term to modify the threshold to gain more control over dot size and dot shape and also reduce the midtone artifacts. 14 Besides these models based on error diffusion, there are also other models for second-order FM halftoning reported in the literature. [15][16][17] Lau et al 15 proposed a technique for generating green-noise halftones by employing a dither array referred to as a green-noise mask.…”

Section: Introductionmentioning

confidence: 99%

High-speed first- and second-order frequency modulated halftoning

Gooran¹,

Kruse²

2015

J. Electron. Imaging

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Abstract. Halftoning is a crucial part of image reproduction in print. First-order frequency modulated (FM) halftones, in which the single dots are stochastically distributed, are widely used in printing technologies, such as inkjet, that are able to stably print isolated dispersed dots. Printers, such as laser printers, that utilize electrophotographic technology are not able to stably print the isolated dots and, therefore, use clustered-dot halftones. Periodic clustered-dot, i.e., amplitude modulated halftones are commonly used in this type of printer, but they suffer from an undesired periodic interference pattern called moiré. An alternative solution is to use second-order FM halftones in which the clustered dots are stochastically distributed. The iterative halftoning techniques that usually result in well-formed halftones operate on the whole input image and require extensive computations and thus, are very slow when the input image is large. We introduce a method to generate image-independent threshold matrices for first-and second-order FM halftoning. The first-order threshold matrix generates well-formed halftone patterns and the second-order FM threshold matrix can be adjusted to produce clustered dots of different sizes, shapes, and alignment. Using predetermined and image-independent threshold matrices makes the proposed halftoning method a point-by-point process and thereby very fast. 1 Introduction Many reproduction devices, e.g., printers, have a limited number of output states, leaving the choice of printed and nonprinted spots in order to reproduce a shade. Thus, continuous tone gray-scale or color images need to go through a process called halftoning before being printed. Because of the fact that the human eye is limited in its capacity to resolve small dots and dots close to each other, if the viewing distance is long or the dots are small enough, the human eye is not able to distinguish between the original image and the halftone one. Hence, since the human eye acts as a lowpass filter, the halftones appear pleasing if the difference between the original and the halftone is small in the low-frequency region.Halftoning algorithms are commonly categorized into two main subgroups, called amplitude modulated (AM) and frequency modulated (FM). In AM, i.e., periodic clustered-dot halftones, different shades of gray are reproduced by changing the size of the dots while keeping their spacing constant. In first-order FM, dispersed-dot halftones, on the other hand, the size of the dots is constant while their density (or frequency) is variable. There is also another type of halftones, which we call second-order FM in this paper, in which both the size and the frequency are variables. In these halftones, the clustered dots are stochastically distributed. In literature, this type of halftones is also referred to as stochastic clustered-dot halftones and even green-noise dither patterns. In Ref. 1, the radially averaged power spectrum (RAPS) curves for these three types of halftones, i.e., AM, firstorder...

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A New Framework for Characterization of Halftone Textures

Chang

Allebach

Proceedings. (ICASSP '05). IEEE International Conference on Acoustics, Speech, and Signal Processing, 2005.

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Clustered-minority-pixel error diffusion

Cited by 10 publications

References 8 publications

Rank-ordered error diffusion: method and applications

Rank-ordered error diffusion: method and applications

High-speed first- and second-order frequency modulated halftoning

A New Framework for Characterization of Halftone Textures

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