Conventionally, measuring and thus reproducing yarn color is mainly done in an indirect way, involving the preparation of yarns in card or even fabric forms, which consumes both time and labor. A direct yarn color measurement and reproduction method based on a multispectral imaging system would be one solution to avoid this problem. In this research, 100% raw cotton yarn hanks dyed using several reactive colorants, being different sample sets, were measured by both a spectrophotometer in yarn card form and a multispectral imaging system innovatively in yarn form itself, for back-prediction and fore-prediction matching comparisons. Experimental results showed that the multispectral imaging system can perform closed-loop color reproduction satisfactorily by yarn form color measurements, with color difference means all within industrial tolerance. This new method is capable of shortening the yarn specimen handling time and, more importantly, giving more accurate yarn color measurements without the influence of neighboring colors, so as to give improved coloration accuracy.
Color discrepancies between the left and right image in a stereoscopic image cause many problems, including a reduction of the three-dimensional effect and increased visual fatigue. Thus, color matching in a stereoscopic image is very important for three-dimensional display systems. Therefore, a hierarchical integrated color matching method based on image decomposition is proposed for stereoscopic images. In the proposed method, global and local color discrepancies generated in a stereoscopic image are effectively reduced by histogram matching and illuminant estimation using image decomposition. The stereoscopic image is first decomposed into a base layer and several texture layers. Each decomposed layer is then matched using cumulative histogram matching and a multi-scale retinex algorithm. Lastly, inverse decomposition is applied to each layer to reconstruct the corrected stereoscopic image. Experimental results show that the proposed method has a better color matching performance in comparison with previous methods.
A computer aided design system for determining the color appearance of metallic automotive coatings has been developed. A sketch based bidirectional reflectance distribution function design interface allows simple concept art to be used to style new metallic car colors. The final design is specified using industrial measurement standards for metallic color appearance, and paint formulations are determined by employing an automotive refinish system. A virtual collection of existing automotive paints, specified using the measurement standard, is provided, and tools for searching this database, for both design and manufacturing purposes, are described. The system is assessed by using it in industrial and educational design studios.
Projection displays, compared to other modern display technologies, have many unique advantages. However, the image quality assessment of projection displays has not been well studied so far. In this paper, we propose an objective approach to measure the relative contrast of projection displays based on the pictures taken with a calibrated digital camera in a dark room where the projector is the only light source. A set of carefully selected natural images is modified to generate multiple levels of image contrast. In order to enhance the validity, reliability, and robustness of our research, we performed the experiments in similar viewing conditions at two separate geographical locations with different projection displays. In each location, we had a group of observers to give perceptual ratings. Further, we adopted state-of-art contrast measures to evaluate the relative contrast of the acquired images. The experimental results suggest that the Michelson contrast measure performs the worst, as expected, while other global contrast measures perform relatively better, but they have less correlation with the perceptual ratings than local contrast measures. The local contrast measures perform better than global contrast measures for all test images, but all contrast measures failed on the test images with low luminance or dominant colors and without texture areas. In addition, the high correlations between the experimental results for the two projections displays indicate that our proposed assessment approach is valid, reliable, and consistent.
In this article, the authors propose a method to estimate the reflectance property from refocused images from a light source reflected on an object. The blurred information of the light source on the surface of the object is expected to be a practical method to estimate the reflectance property, although various methods have previously been proposed. Because the degree of blurred information is changed with the position of focus in the camera, the authors introduce a light field camera that can change the position of focus after the image is captured. In this research, the authors chose the refocused image where the light source is focused through the reflection on the object surface. Based on the blurred information of the focused light source, they estimate the reflectance property of the object. The estimated reflectance property is applied to inverse rendering for auto material appearance balancing.