When a color video system with highly accurate color reproduction is designed, a good measure is required for evaluating the image quality including the color reproduction. There are some degradation sources in a total imaging system from image acquisition to image reproduction. Color random noise is one of major degradations which is often added in image capture phase. In this paper, we invest...

Color gamut mapping plays a crucial role in color management. Depending on the application, it is sometimes desirable to perform color gamut mapping by shifting the lightness and compressing the chroma of an out-of-gamut color while preserving the perceived hue of the color. The term Òperceived hueÓ is used to distinguish between the visual sensation of hue and metric hue angle (e.g., CIELAB hu...

In digital image reproduction, it is often desirable to compute image difference of reproductions and the original images. The traditional CIE color difference formula, designed for simple color patches in controlled viewing conditions, is not adequate for computing image difference for spatially complex image stimuli. Zhang and Wandell [Proceedings of the SID Symposium, 1996; p 731–734] introd...

Standardized in 1976 as a uniform color space, CIELAB is extensively utilized in color science and engineering applications. CIELAB provides both a color difference formula and correlates for common perceptual descriptors of color. Deficiencies in both areas are well-known, and based on these known limitations, numerous fixes have been developed yielding alternative color difference formulae th...

color match between fiber-reinforced composite (frc) restorations and teeth is an imperative factor in esthetic dentistry. the purpose of this study is to evaluate the influence of veneering composites and fibers on the color change of frc restorations.glass and polyethylene fibers were used to reinforce a direct microhybrid composite (z250, 3m espe) and a microfilled composite (gradia indirect...

We describe a spatial extension to the CIELAB color metric that is useful for measuring color reproduction errors of digital images. To compute the error, digital color images are spatially ltered using a pattern-color separable method and then converted into the CIELAB representation. Over patterned regions of the image, the reproduction errors measured using the spatial extension of CIELAB co...

OBJECTIVE Evaluate the immediate and cumulative optical whitening efficacy of a blue covarine toothpaste. MATERIALS AND METHODS 180 bovine tooth specimens with similar shade (ΔE < 3.5) were staining of different beverage: black tea(BT), green tea (GT), red wine (RW), orange soda (OS), and brazilian açai juice (AJ), and then submitted to tooth brushing with a blue covarine toothpaste (Op) or a...

Color display calibration, in part, involves mapping input RGB values to corresponding output values in a standardized color space such as CIE XYZ. A linear model for RGB-to-XYZ mapping is based on a 3-by-3 linear transformation matrix T mapping data from (linearized) RGB to XYZ. Such a mapping is often determined by least squares regression on the difference between predicted and measured XYZ ...

The lack of blue hue constancy has been identified as a significant shortcoming of the CIELAB color space. The CIECAM97s, CIELUV, IPT and MLab color spaces have been proposed as alternatives to CIELAB. Color gradients with fixed anchor values were used as stimuli in a visual experiment. This allowed an efficient comparison of the hue constancy of different color spaces. The results show that IP...

We examine mathematical properties of the CIEDE2000 color difference formula and illustrate that the CIEDE2000 color difference is not a continuous function of the CIELAB color pairs between which the difference is calculated. Particularly, we illustrate that ambiguities in the computation of mean hue angle and hue angle differences of color pairs contribute to a discontinuity in the formula fo...