Perfect Color Research Articles

On the regularity of perfect 2-colorings of the Johnson graph

We study perfect colorings of the Johnson graph in two colors. We give sufficient conditions for a perfect coloring of the Johnson graph to be k-regular and present examples of perfect colorings. The proof of the theorem is in many respects similar to the proof of the result by Etzion and Schwartz [1] on k-regularity of perfect codes.

Beyond black and white: A note concerning three-colour-counterchange patterns

The systematic colouring of plane patterns results in a finite number of combinations, when using a given number of colours. This paper introduces a range of concepts associated with the perfect colouring of plane patterns, and presents illustrative examples of 23 three-colour-counterchange possibilities.

Upper Extremity Salvage With a Flow-Through Free Flap

In complex extremity injuries, which include composite tissue lost with devascularization caused by segmental vascular damage, simultaneous coverage of the defects with revascularizations should be required. One-stage reconstruction of both soft tissue coverage and vascular damage can be performed by a flow-through-type free flap. In this series, 5 patients between 13 and 36 years of age with wide composite tissue defects in the cubital region and segmental defects in brachial arteries were operated at our clinic between 1996 and 2003. With the aim of reconstructing the wide tissue defects in the cubital region as well as that of the brachial artery, a radial arterial flow-through flap was applied. The radial artery of the flow-through flap was anastomosed to the proximal ends of the brachial and ulnar arteries in an end-to-end fashion. In 4 of the patients, the radial arterial flow-through flap was prepared from the distal aspect of the wounded forearm and in 1 patient from the contralateral forearm. In the postoperative period, no complications related to the anastomosis were encountered in the flap with all anastomoses found to be patent, and distal circulation was restored. The radial arterial flow-through flap is very useful in the clinical field of major trauma of the cubital region with brachial artery damage with numerous advantages that include the opportunity to work in one single surgical area, shorter dissection times resulting from simple and fixed anatomy, perfect color and tissue adaptation, and the suitability of the vessel caliber and length.

Lower Lip Reconstruction: Introduction of a New Procedure Using a Functioning Gracilis Muscle Free Flap

Subtotal and total reconstruction of the lower lip is a challenge for the plastic surgeon: this lip mainly contributes to the continence function of the oral sphincter. Fasciocutaneous free flaps and local flaps are better suited to the skin laxity of elderly patients; furthermore, larger defects extending to the chin area can be difficult to manage with only local flaps. In an attempt to restore very good function and aesthetics of the lower lip in a single procedure, the authors introduced the use of a functioning (innervated) gracilis free flap. The dynamic sphincter capacity was obtained with the coaptation between the motor branch of the gracilis muscle and the marginal branch of the facial nerve. A facial artery musculomucosal flap replaced the vermilion and the inner side mucosa, and a skin graft from the scalp covered the external surface of the gracilis. The procedure was performed in two cases. In both cases, the authors achieved quite full physiologic lower lip movement with regard to symmetrical spontaneous and voluntary controlled lower lip function, whereas the skin grafts from the scalp and the supraclavicular region had a nearly perfect color match with the reconstructed area. The aesthetic result was excellent compared with the complexity of the reconstructed defect. A functioning gracilis free flap has to be considered among the techniques for complex lower lip reconstruction. It was able to restore very good voluntary function and an extremely fine aesthetic result in a single-stage procedure.

A Comparative Study on Superior Auricular Artery Island Flaps With Various Pedicles for Repair of Periorbital Defects

Superior auricular artery (SAA) island flaps elevated from the retroauricular region have perfect color, thickness, and texture match with facial skin. In this article, reconstruction of periorbital defects with SAA island flaps is presented. Flaps were categorized into three types because they were elevated on three different pedicles. A type 1 flap was a superficial temporal vessel pedicled SAA island flap with antegrade blood flow. A type 2 flap was a reverse flow SAA island flap based on the frontal branch of the superficial temporal artery (STA). A type 3 flap was a reverse flow SAA island flap based on the parietal branch of STA. Fourteen patients (9 females and 5 males) aged between 31 years and 74 years were treated with these flaps. Two patients with lower eyelid, two patients with upper eyelid, three patients with malar, two patients with infraorbital, one patient with lateral canthal upper eyelid, and four patients with forehead defects underwent surgical intervention. Sizes of the flaps varied between 3x6 cm and 8x6 cm. Venous congestion was observed in all patients in the early postoperative period and lasted for 5 to 9 (mean, 6.6) days in type 1 flap, 5 to 9 (mean, 6.7) days in type 2 flap, and 2 to 5 (mean, 3.6) days in type 3 flap. Apart from distal necrosis of 1x1 cm in one patient and superficial dermal sloughing in two patients, no complications were encountered. Aesthetically and functionally successful results with minimal donor site morbidity were obtained in all patients during the 2 to 22 (mean 10.8) month follow-up period.

Spectral adaptation

AbstractChromatic adaptation refers to the ability of the human visual system to adjust to the color of the illumination, or other prevailing stimuli, such that perceived object colors vary far less with changes in illumination than would be expected from simple radiometry or colorimetry. Models of chromatic adaptation are generally formulated as extensions of the von Kries hypothesis of some sort of independent gain control mechanisms operating on the three types of cone, or similar signals. This article introduces a new way to model the phenomenon with no requirement for the first stage chromatic processing. This model is referred to as a spectral adaptation model since it acts upon spectra rather than chromatic signals such as tristimulus values. The spectral adaptation model was compared with other models of adaptation both computationally and through limited psychophysical data. It is shown to have reasonable and flexible performance and could be of practical value in applications such as spectral image reproduction. A limiting case of the spectral model, a model of perfect color constancy, is also described and compared with traditional colorimetric chromatic adaptation models. © 2007 Wiley Periodicals, Inc. Col Res Appl, 32, 100 – 112, 2007

Perfect coloring and linearly χ‐bound P6‐free graphs

AbstractWe derive decomposition theorems for P6, K1 + P4‐free graphs, P5, K1 + P4‐free graphs and P5, K1 + C4‐free graphs, and deduce linear χ‐binding functions for these classes of graphs (here, Pn (Cn) denotes the path (cycle) on n vertices and K1 + G denotes the graph obtained from G by adding a new vertex and joining it with every vertex of G). Using the same techniques, we also obtain an optimal χ‐binding function for P5, C4‐free graphs which is an improvement over that given in [J. L. Fouquet, V. Giakoumakis, F. Maire, and H. Thuillier, 1995, Discrete Math, 146, 33–44.]. © 2006 Wiley Periodicals, Inc. J Graph Theory 54: 293–306, 2007

Versatility of the Bilobed Cervical Skin Flap for Total Ear Reconstruction in the Unfavorable Temporoauriculomastoid Region

The unfavorable temporoauriculomastoid region is a serious clinical problem that makes total ear reconstruction a real challenge. In patients who have it, all local flap solutions to provide skin coverage to the cartilage frame are precluded because of loss and/or severe scarring of the regional skin in association with loss of the axial vascularity of the region. In the current literature, all available techniques for these patients are lengthy and risky free flap procedures that can provide a poor quality of skin coverage with no aesthetic harmony at best. In this article, the authors describe the use of the bilobed cervical flap as a new technique for providing skin coverage in total ear reconstruction for patients with an unfavorable temporoauriculomastoid region. Over a period of 6 years, the technique was used in seven patients between the ages of 19 and 52 years. In all patients, the entire skin of the temporoauriculomastoid region was either lost or badly scarred. Moreover, use of the ipsilateral temporoparietal fascia was not possible because of impaired axial vascularity of the region. Except for mild venous congestion at the distal part of the primary flap, the flaps healed uneventfully in all patients. The patients were followed up for 1 to 4 years. The results were excellent in all patients. Providing a thin, pliable, hairless, and well-vascularized skin cover with a perfect color match, the bilobed cervical flap seems to be a useful solution to overcome the skin coverage dilemma in patients with an unfavorable temporoauriculomastoid region.

Optically adjustable display color gamut in time-sequential displays using LED/Laser light sources

Recently, various wide color gamut displays have been developed. Because of color gamut differences between wide gamut displays and the standard definitions, the color reproduction on such display system is not equal to original images. To overcome this, a color transformation such as gamut mapping algorithm is applied in conventional systems. But this manipulates only the video signal that would reduce the signal dynamic range and produces quantization error of video signal. In this paper, we propose a new optical Color Gamut Processing instead of an image data mapping. In the method, an individual color gamut of the standard definitions can be composed of an optical mixture of original primary colors. As a result, a perfect color match for the various standards can be realized within a display gamut without any signal artifacts. Moreover the same concept is applied to the video stream in order to elevate scene luminance. A scene-adaptive Dynamic Color Gamut Processing measures a color gamut for every video frame and adjusts a matched display color gamut so that it is able to increase display contrast in comparison to conventional display systems.

Color management for perfect color images

Applying color management (CM) techniques can result in printed images that perfectly match the image on your monitor. Each computer peripheral device sees colors in a somewhat different “color space.” CM systems use individual profiles to ensure that all peripheral devices see colors the same way.

Dynamical Model of QCD Vacuum and Quark Confinement**The project supported by Science Foundation of the Ministry of Science and Technology of China under Grant No. 2100CCA00700

The phase transition of a simple local gauge model is investigated in terms of the Nambu–Jona-Lasinio mechanism and it is pointed out that the physical vacuum of QCD is bound state of quark-antiquark pairs which can be viewed, generally, as a nearly perfect color dia-electric medium. An important relation between the vacuum expectation value of gauge fields and scalar fields is also derived by solving the Euler equation for the gauge fields. Based on this relation the gauge potential is given which can be used to explain the asymptotic behavior and confinement of quarks in a hadron, and at the same time the Yukawa potential of strong interaction can be given too.

New concepts for plastic exterior body panels

“Hybrid materials” and “modularit” sum up the trend in modern vehicle body design. Since individual parts and modules are likely to be sourced from a variety of suppliers, colour matching is likely to be a growing problem. The ollowing article presents a possible solution developed by BASF. It consists of a coated or pigmented plastic film that not only guarantees a perfect colour match but also eliminates the use of conventional spray coating of vehicle bodies.

Improving Color Tracking in In-Plane Switching Mode Liquid-Crystal Displays

AbstractColor tracking describes the ability of a display to faithfully reproduce the color quality of the source image. In liquid-crystal displays (LCDs), color tracking is dependent on brightness. In order to achieve high-performance color reproduction in LCDs, the accuracy of color tracking needs to be improved. By analyzing the characteristics of twisted-nematic (TN) and in-plane switching (IPS) modes of display, the cause of poor color tracking in each mode and the differences in their causes can be clarified. In TN mode displays, both chromaticity and brightness relate to the director configuration, that is, the directional alignment of the rod-like molecules of the liquid crystals, which varies with applied voltage. The ideal IPS LCD, by virtue of its operating principle, theoretically achieves perfect color tracking; however, in actual use, the color tracking is less than optimal due to twist deformation caused by the fixed directors on the alignment layer. Based on our analysis of these phenomena, we propose strategies for improving color tracking in IPS LCDs.

Stabilized Three-Level Highlight Color Imaging with High Resistance Developer

A one-pass process with combinations of charged and discharged area developments is used for three-level highlight color imaging. The process yields excellent gradation images between black and color because of perfect color registration. However, there are some special problems of fringe images, blurring, and appearance of white spots in the second color images, etc. Employing a very low resistance developer can overcome these problems. As a consequence, though, this type developer results in developing instability due to charge leakage. A highly stable three-level process without these problems is proposed which employs a higher resistance developer without charge leakage and applies a newly developed edge effect control technology and the first color developing station with dual rotation rollers. This process provides excellent highlight color images.

Color constancy in goldfish: the limits.

Color constancy was investigated in behavioral training experiments on colors ranging from blue to yellow, located in the color space close to Planck's locus representing the main changes in natural skylight. Two individual goldfish were trained to peck at a test field of medium hue out of a series of 13-15 yellowish and bluish test fields presented simultaneously on a black background. During training the tank in which the fish were swimming freely was illuminated with white light. Correct choices were rewarded with food. During the tests differently saturated yellow or blue illumination was used. The degree of color constancy was inferred from the choice behavior under these illuminations. Perfect color constancy was found up to a certain degree of saturation of the colored light. Beyond this level test fields other than the training test field were chosen, indicating imperfect color constancy. Color constancy was quantified by applying color metrics on the basis of the goldfish cone sensitivity functions.

Stabilized 3-Level High Light Color Imaging with High Resistance Developer

For the 3-level highlight color imaging, a 1-pass process with combinations of charged and discharged area developments is used. It has an advantage for excellent gradation images between black and color because of perfect color registration. Otherwise, there are some unique problems of fringe images, blur, white spots in the 2nd color images, etc. Employing very low resistance developer gives a solution for these problems. However, this method causes developing instability due to a charge leakage instead.The highly stable 3-level process without the problems, employing the higher resistance developer without the charge leakage and applying newly developed edge effect control technology and the 1st color developing station with dual rotation rollers, are proposed in this study.Finally a stable process and an excellent highlight color image can be provided.

COLOR NORMALIZATION FOR COLOR OBJECT RECOGNITION

Color images depend on the color of the capture illuminant and object reflectance. As such image colors are not stable features for object recognition, however stability is necessary since perceived colors (the colors we see) are illuminant independent and do correlate with object identity. Before the colors in images can be compared, they must first be preprocessed to remove the effect of illumination. Two types of preprocessing have been proposed: first, run a color constancy algorithm or second apply an invariant normalization. In color constancy preprocessing the illuminant color is estimated and then, at a second stage, the image colors are corrected to remove color bias due to illumination. In color invariant normalization image RGBs are redescribed, in an illuminant independent way, relative to the context in which they are seen (e.g. RGBs might be divided by a local RGB average). In theory the color constancy approach is superior since it works in a scene independently: color invariant normalization can be calculated post-color constancy but the converse is not true. However, in practice color invariant normalization usually supports better indexing. In this paper we ask whether color constancy algorithms will ever deliver better indexing than color normalization. The main result of this paper is to demonstrate equivalence between color constancy and color invariant computation. The equivalence is empirically derived based on color object recognition experiments. colorful objects are imaged under several different colors of light. To remove dependency due to illumination these images are preprocessed using either a perfect color constancy algorithm or the comprehensive color image normalization. In the perfect color constancy algorithm the illuminant is measured rather than estimated. The import of this is that the perfect color constancy algorithm can determine the actual illuminant without error and so bounds the performance of all existing and future algorithms. Post-color constancy or color normalization processing, the color content is used as cue for object recognition. Counter-intuitively perfect color constancy does not support perfect recognition. In comparison the color invariant normalization does deliver near-perfect recognition. That the color constancy approach fails implies that the scene effective illuminant is different from the measured illuminant. This explanation has merit since it is well known that color constancy is more difficult in the presence of physical processes such as fluorescence and mutual illumination. Thus, in a second experiment, image colors are corrected based on a scene dependent "effective illuminant". Here, color constancy preprocessing facilitates near-perfect recognition. Of course, if the effective light is scene dependent then optimal color constancy processing is also scene dependent and so, is equally a color invariant normalization.

Two Classes of Color Constancy: Perfect Color Constancy and Partial Color Constancy.

If a mere apparent color (apparent-color) from an object surface is equal to a color perception as an attribute of the same object surface (surface-color), this condition should be called “perfect color constancy.” If not, the condition should be called “partial color constancy.” We looked into the distinction between these two classes of color constancy, while changing illuminant chromaticity around D65. A small room with variable-chromaticity illuminant was used. The walls were painted with N5 gray. A CRT monitor was placed behind an aperture on the front wall, so that the observer perceived the CRT monitor as a reflecting surface on the wall. Observers were asked to make unique-white settings, in terms of both apparent-color and surface-color, under various chromaticites of illuminants. The shift in unique-white represents the shifts in visual sensitivity, and an analysis based on a simple von Kries type model was made. Cone weights for each cone class were defined to represent the state of chromatic adaptation. The change in cone weights show that the sensitivity shift in the visual system follows illuminant chromaticity change only around white, and the visual system was not able to follow illuminant chromaticity change for saturated illuminants. An additional experiment confirmed that these results had no contamination of simultaneous contrast effect. This result may correspond to the fact that “perfect color constancy” holds under whitish illuminant while “partial color constancy” holds under colored illuminants. In conclusion, we suggest that the “perfect color constancy” can be achieved only by von Kries-like sensitivity change, and the “partial color constancy” requires further processing at the higher stages of the human visual system.

Color, PDF, & OPI … How It Fits Together

Most prepress companies or print shops use print spool systems and so-called Open Prepress Interface (OPI) servers to optimize their workflow. Helios Software GmbH is a well-known vendor of such software. With the standards set by the International Color Consortium (ICC) and with proper use of the Portable Document Format (PDF), as specified by Adobe, a consistent color managed workflow can now be implemented in server-based environments. The purpose of this article is threefold:1. There are ongoing discussions about where color matching should happen: in the print client's application, in the RIP of the final output device, or somewhere else? Helios advocates color matching and separation in the print spooler or the OPI system where the final destination of a print job is best known. The article tells why and how.2. Until recently, PDF could be used for electronic delivery and viewing on screen as well as for black & white printing, but not for color production. However, with proper server-based color matching and PDF support as e.g. with Helios PDF Handshake and Print Preview, perfect color printing of PDF documents on any PostScript device and even to non-PostScript printers like PC ink-jet printers becomes a reality.3. What makes a good output device a perfect fit in a server-based workflow? The article lists some features which allow smoother and more efficient print production.

Effect of Ambient Illuminant on Surface Colour Constancy

Generally, we are completely enclosed in a real environment, which may act as an entire view-field or adapting field. But in most studies on colour constancy experiments have been made with spatially restricted stimuli. We built a room with gray (N5) walls inside to measure the effect of ambient illuminant on colour constancy. The room illuminant could change its colour from white (D65) to either blue, orange, green, or purple. The observer sat in this main room and adapted to the illuminant for 5 min before the start of the experiment. The observer was shown a smaller room, which had the same variable-colour illuminant, through an aperture (11 deg × 8 deg) in the left side wall. We set the illuminant for each room independently, but in asymmetric illuminant-colour conditions either was set to white. The observer viewed the central part of a colour CRT monitor, placed behind a small aperture (5 deg × 5 deg) in the front wall, and matched its colour appearance to four OSA colour chips in the smaller room. Under symmetric illuminant conditions, eg blue vs blue, the observers' settings showed a complete match with the physical chromaticities of the colour chips. In asymmetric illuminant conditions, eg white vs blue, matched colours showed systematic deviations from both physical chromaticities and colour constancy. This implies that taking the ambient illuminant as adapting field did not yield perfect colour constancy. We introduce a simple model based on incomplete adaptation to the ambient illuminant and a spatial-interaction mechanism, which accounts for our results.