Textiles screen-printed with photochromic ethyl cellulose-spirooxazine composite nanoparticles

Photochromic compounds change colour on exposure to light, while the reversion may be attributable either to radiation or may be thermal. The use of photochromism on fabrics can provide new opportunities to develop smart textiles; for example, sensors and active protective clothes. Ethyl cellulose-1,3-dihydro-1,3,3,4,5 (and 1,3,3,5,6) -pentamethyl-spiro-[2H-indole-2,3′-(3H)naphtha(2,1-b)(1,4)oxazine] composites were prepared by an oil-in-water emulsion, solvent evaporation method in order to form easily suspendable and fatigue-resistant photochromic nanoparticles in screen-printing paste. Their size was well below 1 μm and did not change substantially over a wide range of dye concentrations. After screen-printing, a homogenous photochromic layer was built on a cotton substrate surface, which represented substantial blue colour development in CIELab colour space measurements because of ultraviolet light, even at a dye concentration of 0.045% w/w. The addition of a photodegradation inhibitor, Tinuvin 144, further increased the coloration of the printed fabric

Measurement of the effect of chromaticity and intensity on colour representation parameters of a CRT display

The aim of the measurement detailed in this paper was to measure the just-noticable stimuli of the participating subjects. The stimuli were defined by chromaticity and intensity as the main parameters of the mathematical model. The results show correlance between intensity and the just-noticable stimuli, as described in the Weber-Frechner Law but a contradiction was shown after the analysis in the function of chromaticity. This contradiction can be explained by the difference between the sensitivity of the three cones of the eye

Analysis of colour moiré phenomenon in colour space

Moiré topographic technique is widely used for three-dimensional surface reconstruction. One of the main problems is determination of the absolute order of a fringe for finding the depth difference between two points in moiré patterns, i. e. convex and concave surfaces distinction. Most solutions of the problem are very complicated; also they usually require several moiré images. Application of colour-encoded gratings in projection moiré method allows solving the problem simply and quickly. The authors analyze the information that contains in colour moiré fringes and estimate its effectiveness. With this purpose device independent simulations for colour formation of one moiré fringe in colour space by different conditions were made

NUMERISCHE METHODE ZUR ERMITTLUNG VON SIMULTANEN FUNKTIONEN, DIE MIT INDIREKTER METHODE GEMESSEN WURDEN

A new method for the calculation of color-functions was found by the authors. The applied computer programs give reasonable functions with the data measured on indirect ways

Shape identification using Moiré topography

The shape identification method, including measurements of shape with incoherent light, is shown in the present article. This method is based on the data of Moiré sensor and linear regression method. We give general formulas and an algorithm for such computation and some results obtained by using this algorithm

Measurement of color defective and normal color vision subjects´ color and luminance contrast threshold functions on CRT

To perform a more complete diagnosis on the effect of color vision deficiency on visual performance we measured luminance and color contrast threshold functions. Measurements were carried out on CRT for a range of spatial frequencies on color deficient and normal color vision individuals. Luminance and color contrast threshold is a measure of the recognition limits of low luminance and color contrast patterns. Both of them are function of the image features and spatial frequency. In our test patterns of stripes with a sinusoidal luminance profile were displayed on the monitor. The subject´s task was to detect the presence and orientation of these gratings. In the study 6 normal and 6 anomalous trichromats were measured. In the case of color contrast threshold measurement it is essential to apply colors with identical luminance sensation, otherwise the test person might be able to differentiate between the presented colors not based on hue but based on luminance. The increasing accessibility of computers and color monitors provides a platform for color vision tests based on brightness sensation correction. In our experiment we define the subject´s relative luminance sensation stimulated by the primary colors of the monitor with the method of direct heterochromatic photometry. Although, there were no significant differences in luminance contrast threshold between normal color vision and color deficient subjects, we found significant reduction in red-green color contrast threshold at all color defectives. The results prove the assumption that color deficiency has a negative effect on noticing details in color environment

The Effect of the Field of Adaptation on Chromatic Discrimination Ellipses

In this paper results of chromatic discrimination measurements obtained in two lighting scenarios are compared. Chromatic discrimination thresholds were measured in relation with systematically manipulated chromaticities seen under different visual angles. In both cases the Ellipse module of the Cambridge Colour Test (CCT) was obtained binocularly by normal colour-observers. Discrimination ellipses fitted to the measured thresholds were compared in terms of the adapting chromaticity and the visual angle of the adapting stimulus. Our findings show that changes in the reference chromaticity of the CCT have stronger effect on the elongation of the chromatic discrimination ellipses compared to the effect of the adapting chromaticity obtained in a light booth.Further comparison of discrimination thresholds estimated towards the confusion directions and the corresponding radii of the Ellipse test results suggests that the reliability of the Ellipse test results depends on the relation between the measurement directions and the confusion directions

MOIRÉ-METHODEN BEI DER MESSUNG UND UNTERSUCHUNG DER OBERFLÄCHENGESTALTEN, GESTALTFEHLER UND GESTALTVERÄNDERUNGEN

This articIe summarises the moire-methods for measurement of figures with incoherent light. A patented measuring instrument developed at the Institute of Precision Mechanics and Optics is reported on. Some new methods for the measuring of figure errors are described