Cost function analysis for stochastic clustered-dot halftoning based on direct binary search

Goyal, Puneet; Gupta, Madhur; Staelin, Carl; Fischer, Mani; Shacham, Omri; Allebach, Jan P.

doi:10.1117/12.878598

Cited by 4 publications

(5 citation statements)

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“…The advantages of FM are fine detail reproduction, due to small size halftone elements, and the ability to reproduce very light areas (Gooran 2006). On the other hand, some printing techniques are not suitable for FM halftoning, as it is the instance with printers using electrophotographic (EP) technology, due to their incapacity of stably rendering isolated dots (Goyal et al 2011). Laser printers are an example of printers using EP technology.…”

Section: Figure 34: Am Halftoned Image (30 Lpi)mentioning

confidence: 99%

“…AM halftoning is preferred in some printing technologies like electrophotography (Goyal et al 2011) or flexography (Gooran 2005), where the nature of the reproduction technology makes this halftoning algorithm reproduce the images in a more stable way and without artefacts (Goyal et al 2011). The challenge of AM halftoning algorithms is, as discussed in Section 3.3.1, moiré appearance, dealt with by adjusting each channel in a specific angle, thus forming a rosette pattern.…”

Section: Introductionmentioning

confidence: 99%

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Halftoning for Multi-Channel Printing : Algorithm Development, Implementation and Verification

Elias¹

2014

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Section: Figure 34: Am Halftoned Image (30 Lpi)mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Halftoning for Multi-Channel Printing : Algorithm Development, Implementation and Verification

Elias¹

2014

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“…This procedure continues until the last iteration, i.e., iteration 256 2 ∕2 ¼ 32;768, where the last two empty positions in the threshold matrix are filled with 32,768 and 32,769. Note that when the threshold matrix is generated, it must be normalized between 0 and 1 if the original image is scaled to [0,1]. This is done by dividing all values in the generated threshold matrix by the maximum value plus 1.…”

Section: Threshold Matrix Generationmentioning

confidence: 99%

“…Note that if the dots are placed in a grid, then although the standard deviation is zero, its RAPS curve will show a spike (or spikes) indicating that the halftone does not have the intended blue-noise characteristic. 1 Therefore, this measure can only be used if further checks with RAPS curves are made. In order to find the optimal σ, halftone patches at 1%, 2%, and up to 25% coverage were created using the threshold matrix with different constant σ:s between 1 and 2.7 with a step of 0.1.…”

Section: Optimizing the Filtermentioning

confidence: 99%

“…Clustered dots are, therefore, preferred for this type of printer. 1,4 Besides printers using EP technology, there are other printing technologies such as flexography in which clustered dots are preferred especially in the midtones because the dot gain is lower and better controlled when the dots are clustered. 5 However, although periodic clustered (AM) halftones are quite smooth, they usually suffer from moiré, which occurs because of the periodic interference of different colorant channels.…”

Section: Introductionmentioning

confidence: 99%

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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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Electro-photographic model based stochastic clustered-dot halftoning with direct binary search

Goyal

Gupta

Staelin

et al. 2011

2011 18th IEEE International Conference on Image Processing

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Cost function analysis for stochastic clustered-dot halftoning based on direct binary search

Cited by 4 publications

References 0 publications

Halftoning for Multi-Channel Printing : Algorithm Development, Implementation and Verification

Halftoning for Multi-Channel Printing : Algorithm Development, Implementation and Verification

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

Electro-photographic model based stochastic clustered-dot halftoning with direct binary search

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