How many tooth colors are there?

Objectives: This study aimed to estimate the number of distinct tooth colors using a large dataset of in-vivo CIELAB measurements. It further assessed the coverage error (CE) and coverage error percentage (CEP) of commonly used shade guides and determined the number of shades needed for an ideal guide, using the Euclidean distance (ΔEab) and thresholds for clinical perceptibility (PT) and acceptability (AT) as evaluation criteria.

Methods: A total of 8153 untreated maxillary and mandibular anterior teeth were measured in vivo using calibrated dental photography.

Optimized Pattern Partitioning for Multi-Pass Printing: PARAOMASKING.

In halftone-driven imaging pipelines focus is often placed on halftone pattern design as the main contributor to overall output quality. However, for sequential or cumulative imaging technologies, such as multi-pass printing, an important element is also pattern partitioning - how the overall halftone pattern is divided among the different partial imaging events such as printing passes. Partitioning is usually designed agnostically of the halftone pattern, making it impossible to optimize for the joint effect of halftone and partitioning.

Color-difference formula for evaluating color pairs with no separation: ΔE.

All color-difference formulas are developed to evaluate color differences for pairs of stimuli with hairline separation. In printing applications, however, color differences are frequently judged between a pair of samples with no separation (NS) because they are printed adjacently on the same piece of paper. A new formula, ΔE, has been developed for pairs of stimuli with NS.

Direct Pattern Control Halftoning of Neugebauer Primaries.

Halftoning is a key stage of any printing image processing pipeline. With colorant-channel approaches, a key challenge for matrix-based halftoning is the co-optimization of the matrices used for individual colorants, which becomes increasingly complex and over-constrained as the number of colorants increases. Both choices of screen angles (in clustered-dot cases) or structures, and control over how individual matrices relate to each other and result in over-versus side-by-side printing of the colorants, impose challenging restrictions.

Large color gamut displays with diffraction gratings.

The ability to display a broad variety of colors has great benefits not only in the context of entertainment but also as a means to streamline design in prototyping and manufacturing processes. Displays that use RGB filters or backlights cannot span all colors that occur in nature. To improve the accuracy of color reproduction, there have been attempts to include additional color primaries in displays.

HANS: controlling ink-jet print attributes via Neugebauer primary area coverages.

Ink-jet print attributes such as color gamut, grain, and cost are consequences of the materials and printing technology used and of choices made during color management, color separation, and halftoning operation. Traditionally, color separation determines what amounts of the available inks to use for each reproducible color, and halftoning deals with the spatial distribution of inks that also results in the nature of their overprinting. However, using an ink space as a means of communication between color separation and halftoning gives access only to some of the printed patterns that a printing system is capable of and, therefore, only to a reduced range of print attributes.

Sampling optimization for printer characterization by greedy search.

Printer color characterization, e.g., in the form of an ICC output profile or other proprietary mechanism linking printer RGB/CMYK inputs to resulting colorimetry, is fundamental to a printing system delivering output that is acceptable to its recipients.