Six Color Separation Using Additional Colorants and Quantitative Granularity Metric

Son, Chang-Hwan; Cho, Yang-Ho; Lee, Cheol-Hee; Ha, Yeong-Ho

doi:10.2352/j.imagingsci.technol.(2006)50:1(25)

Cited by 6 publications

(6 citation statements)

References 8 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…To overcome these problems, Son et al proposed the sixcolor separation using additional colorants and quantitative granularity metric, where the light magenta and yellow colorants were used in bright regions to correct the hue difference between the diluted and saturated colorants. 6 The six-color separation method of generating targeted photoink separation paths selected from combinations of diluted and saturated colorants is proposed under the constraints of ink-trapping and a smooth color transition. 7 Yet, since this method focuses on generating a target photo-ink separation path, the hue values for the input M and C inks may differ from those for the separated CLc or MLm colorants.…”

Section: Introductionmentioning

confidence: 99%

“…The proposed method is an updated version of our previous work. 6 While the fundamental idea remains the same, the main difference is the use of Y and Lm in both bright and middle regions to guarantee a smooth color transition. In the previous version, two types of colorant, Lc and C or Lm and M, are used in middle regions, whereas three types of colorant, Lc, C, and Lm or Lm, M, and Y are used in the present updated version.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Improved Color Separation Based on Dot-Visibility Modeling and Color Mixing Rule for Six-Color Printers

Son¹,

Park²,

Ha³

2011

jist

Self Cite

View full text Add to dashboard Cite

A method of converting cyan, magenta, yellow, and black (CMYK) digital values into cyan, magenta, yellow, black, light cyan, and light magenta (CMYKLcLm) in six-color printers is proposed for providing a better print quality with less dot visibility, high color fidelity, and smooth color transition. Based on the attribute of the dependent variable Lm and Lc to M and C, the input M and C digital values are separated into MYLm and CLcLm digital values, respectively, according to three types of region: bright, middle, and dark. In bright regions, the input M digital values are separated into LmY digital values minimizing the colorimetric errors to compensate for the hue difference between M and Lm, while C is separated into LcLm in the same manner. In middle regions, to guarantee a gradual lightness transition between bright and dark regions, M and C are newly included along with LmY and LcLm used in bright regions, respectively, which raises a redundancy problem, i.e., many to one mapping between M and MYLm or C and CLcLm. To solve this problem, a digital-patch-based dot visibility metric, which avoids the need to scan a large number of printed patches, is proposed based on the standard deviation of the lightness component for digitally bilevel patches through model-based error diffusion, thereby making it possible to choose the unique MYLm and CLcLm with the lowest dot visibility score. Finally, in dark regions, the input M and C digital values are modified by the M and C with the closest color to reduce the use of unnecessary amounts of colorant. Moreover, to eliminate the appearance of color tones on the gray ramp, the input gray CMY digital values are converted into CMYK digital values using a simple gray component replacement, and the input CMY digital values in the predefined gray boundary regions are then transformed by a weighted sum of the CMYLcLm obtained from above-mentioned color separation and the separated CMYK on the gray axis. Experimental results show that the proposed method is able to produce printed images with both a lower color difference and a lower dot visibility when compared to conventional methods.

show abstract

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Improved Color Separation Based on Dot-Visibility Modeling and Color Mixing Rule for Six-Color Printers

Son¹,

Park²,

Ha³

2011

jist

Self Cite

View full text Add to dashboard Cite

show abstract

“…Naturally, the graininess differs not only according to the ink coverage and number of levels, but also in relation to the contrast of the ink to the paper -for instance, the graininess of 50% yellow ink coverage will be different than that of 50% black ink coverage. Son et al (2003Son et al ( , 2006 …”

Section: Standard Deviation Of Digital Halftonesmentioning

confidence: 99%

“…Meanwhile, Son et al (2003Son et al ( , 2006 and Son et al (2011) utilize granularity metrics in order to achieve a six-channel separation employing lighter inks. The separation was performed using colorimetric data in Son et al (2003) and Son et al (2006), and spectral data in Son et al (2011).…”

Section: Previous Workmentioning

confidence: 99%

See 1 more Smart Citation

Improving image quality in multi-channel printing - multilevel halftoning, color separation and graininess characterization

Elias¹

View full text Add to dashboard Cite

Color printing is traditionally achieved by separating an input image into four channels (CMYK) and binarizing them using halftoning algorithms, in order to designate the locations of ink droplet placement. Multi-channel printing means a reproduction that employs additional inks other than these four in order to augment the color gamut (scope of reproducible colors) and reduce undesirable ink droplet visibility, so-called graininess.One aim of this dissertation has been to characterize a print setup in which both the primary inks CMYK and their light versions are used.The presented approach groups the inks, forming subsets, each representing a channel that is reproduced with multiple inks. To halftone the separated channels in the present methodology, a specific multilevel halftoning algorithm is employed, halftoning each channel to multiple levels. This algorithm performs the binarization from the ink subsets to each separate colorant. Consequently, the print characterization complexity remains unaltered when employing the light inks, avoiding the normal increase in computational complexity, the one-to-many mapping problem and the increase in the number of training samples. The results show that the reproduction is visually improved in terms of graininess and detail enhancement.The secondary color inks RGB are added in multi-channel printing to increase the color gamut. Utilizing them, however, potentially increases v the perceived graininess. Moreover, employing the primary, secondary and light inks means a color separation from a three-channel CIELAB space into a multi-channel colorant space, resulting in colorimetric redundancy in which multiple ink combinations can reproduce the same target color. To address this, a proposed cost function is incorporated in the color separation approach, weighting selected factors that influence the reproduced image quality, i.e. graininess and color accuracy, in order to select the optimal ink combination. The perceived graininess is modeled by employing S-CIELAB, a spatial low-pass filtering mimicking the human visual system. By applying the filtering to a large dataset, a generalized prediction that quantifies the perceived graininess is carried out and incorporated as a criterion in the color separation.Consequently, the presented research increases the understanding of color reproduction and image quality in multi-channel printing, provides concrete solutions to challenges in the practical implementation, and rises the possibilities to fully utilize the potential in multi-channel printing for superior image quality.

show abstract

Economic approximate-K color printing algorithm

Lin

2013

Multimed Tools Appl

View full text Add to dashboard Cite

Six Color Separation Using Additional Colorants and Quantitative Granularity Metric

Cited by 6 publications

References 8 publications

Improved Color Separation Based on Dot-Visibility Modeling and Color Mixing Rule for Six-Color Printers

Improved Color Separation Based on Dot-Visibility Modeling and Color Mixing Rule for Six-Color Printers

Improving image quality in multi-channel printing - multilevel halftoning, color separation and graininess characterization

Economic approximate-K color printing algorithm

Contact Info

Product

Resources

About