Renzo Shamey

Unique-hue stimulus selection using Munsell color chips

Presented are intra- and inter-observer variability data comparing the unique-hue (UH) selections of sets of males and females, using two different visual experimental procedures incorporating Munsell color chips of varying hue but identical chroma and value. Although 34 of the 40 Munsell hue chips were selected by at least one observer as a UH, selections were generally repeatable. In addition, intra-observer variability represented approximately 15% of inter-observer variability. Also, when only three consecutive Munsell chips were viewed at a time, females showed significantly larger intra-observer variability than males, especially when making unique green selections. However, variability in UH selections was statistically insignificant between males and females when all Munsell chips were viewed simultaneously. No correlation was found between UH selections or intra-observer variability and hue ordering ability.

Notes on the application of the standardized residual sum of squares index for the assessment of intra- and inter-observer variability in color-difference experiments

The standardized residual sum of squares index was proposed to examine the significant merit of a given color-difference formula over another with respect to a given set of visual color-difference data [J. Opt. Soc. Am. A 24, 1823-1829, 2007]. This index can also be employed to determine intra- and inter-observer variability, although the full complexity of this variability cannot be described by just one number. Appropriate utilization of the standardized residual sum of squares index for the assessment of observer variability is described with a view to encourage its use in future color-difference research. The main goal of this paper is to demonstrate that setting the F parameters of the standardized residual sum of squares index to 1 results in a loss of essential properties of the index (for example, symmetry), and is therefore strongly discouraged.

Comparison of naïve and expert subjects in the assessment of small color differences

Determination of the role of subject experience in the development of accurate color difference formulas is of potentially critical concern. As part of a larger multivariable experiment investigating the minimum inter- and intra-subject variability possible among a set of subjects, a study was conducted to compare the performance of 25 novice versus 25 expert visual assessors for a set of 27 pairs of colored textile samples using a controlled psychophysical method and several statistical techniques including t-test, ANOVA, and Standardized Residual Sum of Squares (STRESS) functions. Experts exhibited approximately 43% higher visual difference ratings than novice subjects when assessing sample pairs having small color differences. In addition, a statistically significant difference at the 95% confidence level was found between the judgments made by novice and expert assessors. According to the STRESS function, however, CMC(1:1) and CIEDE2000(1:1) color difference formulas do not show a significant difference in performance when the visual data from either group of subjects are compared.

Perceptual prominence of Hering's chromatic primaries

Reported are results of an experiment involving perceptual assessment of very large color differences using samples representing approximate mean Hering opponent generic unique hues (guHs) based on subject selections, intermediate hues (iHs) using Munsell samples intermediate between guHs, and pairings of both guHs and iHs with a neutral gray. Sample pairs were assessed by 28 color normal subjects twice, with a gap of at least 24 hours between assessments. Results were calculated for individual subjects and the entire group. The hypothesis was that perceived chromatic differences of Herings guHs are larger than those of iHs, and this was found to be statistically valid at the 99% confidence level based on a t-test. In addition, gray as a percept was found to have prominence comparable to that of generic unique hues.

Nonlinear modeling of equilibrium sorption of selected anionic adsorbates from aqueous solutions on cellulosic substrates. Part 1: model development

A new nonlinear isothermal sorption model, incorporating Donnan equilibrium and electrical neutrality in the classical sorption model of direct dyes onto cellulosic substrates, as model adsorbates, is proposed. The nonlinear isothermal model was used to simulate equilibrium sorption of adsorbates containing ionic charges (z) of −2 to −4 on cellulose adsorbents at various temperature (T) and sodium chloride concentrations ([NaCl]). A detailed analysis of simulation results demonstrates that results based on the nonlinear sorption model highly agree with those based on the log-linear sorption model when the deviation in the concentration of sodium ions in the aqueous solution ([Na+]S) relative to [NaCl] used in the sorption system is restricted to <5.0%. Compared to the log-linear model, the nonlinear model avoids using graphical techniques that are relatively insensitive for determining important sorption parameters such as the internal accessible volume (V) and the standard affinity associated with sorption (−Δμ°). The nonlinear sorption model was used to examine the correlation of fit for previously reported sorption data. The model parameters V and −Δμ° based on curve fits were used to estimate V for cellulose as well as −Δμ°. The values were found to match those based on the conventional log-linear model when deviations of [Na+]S relative to

Performance of select color-difference formulas in the blue region

\overline{{[{\text{Na}}^{ + } ]_{S} }}

Nonlinear modeling of equilibrium sorption of selected anionic adsorbates from aqueous solutions on cellulosic substrates: part 2: experimental validation

were below 5%. The nonlinear model therefore provides a convenient and accurate technique to interpret the sorption of a range of anionic adsorbates on cellulosic substrates.

Scaling perceived saturation

ABSTRACT A water-soluble spirooxazine may be successfully applied directly as dye to produce photochromic silk fabric. Molecular modelling, using the CAChe system, provides a good prediction of its photochromic properties. The dyed fabric shows good colour build-up under UV irradiation and reverts slowly to the original colour when the UV source is removed. It is observed that wet fabric shows better photochromic performance than after drying.