Showing 5 results for S. H. Amirshahi
S. H. Amirshahi,
Volume 14, Issue 2 (1-1996)
Abstract
An algorithm is suggested for implementation of unlimited primaries in two-constants Kubelka-Munk color matching attempt. Allen's method for tristimulus color matching which was limited to four colorants in two constant theory, dealt with inversable matrices. By application of the pseudo-inverse, it is not necessary to limit the number of primary colors to four as Allen suggested. The suggested method is programmed to a color matching attempt with five pre-colored fibers.
H. Khalili S. H. Amirshahi,
Volume 17, Issue 1 (7-1998)
Abstract
The proposed algorithm suggests a new method for determination of K/S value of primaries based on linear least Squares Technique. By applying the matrix pseudoinverse, a modification is introduced to eliminate the limitation on the numbers of applied dyes in one – constant Kubelka-Munk theory. The selection of dyes for tristimulus matching are also done on the basis of the initial spectrophotometric results. The applicability of suggested methods are tested through a computer colour matching attempt with more/less than three primaries.
A. Shams Nateri, S. H. Amirshahi and M. Latefi,
Volume 21, Issue 2 (1-2003)
Abstract
In the present work the reflection behavior and the color appearance of acrylic yarns, as pile yarns used in carpet and pilled fabrics, are considered along their lengths as well as their cross- sections. Differences between longitudinal and cross-sectional reflection behaviors of yarns are measured in different yarn densities and hues and explained by the geometric model. The results of experimental work show that the average of reflectance and lightness values along yarns' length, with identical hue, are higher than values obtained from their cross-section. Besides, the lightness values of cross-sectional of samples, with identical hue, increase when the density of yarns in holder cell increases. The metric chromas as well as the hue angles of samples, dyed with the same dyestuff are different in two directions and lead to color difference values between 3.35 and 27.84 under D65 Illumination and CIE 1964 standard observer in CIELAB color difference formula. The reflection differences between two directions are analyzed using the geometric model and it is found that they originated from different optical passes through the fibers in the mentioned modes.
Keywords: Reflection behavior, Geometric model, Acrylic yarn
M. Taghavi Ghadikolaee and S. H. Amirshahi,
Volume 24, Issue 2 (1-2006)
Abstract
: The CIECAM97s and its revision, as a colour appearance model, were applied for a series of fabrics with different colours and depths to explain their colour appearance coordinates in similar viewing conditions. The results show that due to some modifications which expand the scale, the modified model has improved capadilities in calculating chroma. Besides, the calculations were simpler for the revised version of CIECAM97s model while the results from the two models were the same.
S. Amiri and S. H. Amirshahi,
Volume 26, Issue 2 (1-2008)
Abstract
The reflectance factors of transparent fibers, free delustering agent, are predicted by geometric as well as Kubelka-Munk models.
Transparent fibers are simulated by a net of glass capillary tubes containing different solutions of dyestuffs. Based on the results, prediction of the reflectance factor of capillary net by geometric model is relatively better than those obtained from Kubelka-Munk model. However, the geometric model suffers from a complex and massive computation process. Generally speaking, the geometric model performs better for dark transparent samples due to the ignorable internal scattering phenomena. On the other hand, the Kubelka-Munk model provides better results for light samples, where the geometric model fails in acceptable prediction.
