Color Image Formation Research Articles

Principles of color formation in Chinese painting and ceramic painting

The art of traditional painting and ceramic painting in China has a long tradition, in particular in understanding the role of color in the compositional and semantic structure. The principles of creating a color image have long been associated with national peculiarities of perception of shades and their combinations, as well as philosophical ideas. Technological features and properties of glazes imposed certain restrictions on the use of expressive possibilities of color by Chinese ceramic artists. The object of this research is the works of Chinese painting and ceramics, the subject is the principles of color formation in these arts. Particular attention is paid to identifying similarities in approaches to color transfer in paintings and ceramics. The author's special contribution to the study of the problem is an attempt to characterize and compare the role of color in the art of Chinese painting and ceramic painting. The article defines a number of general principles of correlation and harmonization of colors in the two arts. The traditions of the color formation of works of various epochs are traced, the peculiarities of their evolution are established, the colors characteristic of painting and painting ceramics of different historical periods are revealed. The article examines the essence and symbolism of different colors, which are based on national philosophical and cultural ideas. The conclusion is made about the significance of the color image and color formation for the works of ceramics and painting in China.

Photosensitive Alignment: Advanced Electronic Paper-Based Devices

In this review we describe the reversible photoalignment effect imposed on the director in nematic liquid crystals that provides an approach for fabrication of advanced optically addressed devices. Several new concepts have been developed to render photosensitive materials during the past decade. Functional soft azo dye compounds exhibiting distinct functionalities in response to polarized light are highly desirable for fabrication of optically rewritable electronic paper. An optically rewritable element base using simple and inexpensive materials can potentially enable the development of novel environmentally friendly, paper-like gadgets with improved functionality over regular electronic paper. We argue that an optically rewritable technique is relevant for some applications, where conventional paper might be irrelevant. In particular, we have tested and discussed several techniques of color and 3D image formation. This strategy for fabrication of novel devices offers versatile methods for visualization. We also show that the intensity modulation of the irradiation light has a potential to generate improved grayscale visualization. This principle is based on the statistical distribution control of photosensitive azo dye molecules, driven by the incident polarized light. Additionally, we discuss the functional characteristics of the developed prototypes.

Power Phase Apodization Study on Compensation Defocusing and Chromatic Aberration in the Imaging System

We performed a detailed comparative study of the parametric high degree (cubic, fourth, and fifth) power phase apodization on compensation defocusing and chromatic aberration in the imaging system. The research results showed that increasing the power degree of the apodization function provided better independence (invariance) of the point spread function (PSF) from defocusing while reducing the depth of field (DOF). This reduction could be compensated by increasing the parameter α; however, this led to an increase in the size of the light spot. A nonlinear relationship between the increase in the DOF and spot size was shown (due to a small increase in the size of the light spot, the DOF can be significantly increased). Thus, the search for the best solution was based on a compromise of restrictions on the circle of confusion (CoC) and DOF. The modeling of color image formation under defocusing conditions for the considered apodization functions was performed. The subsequent deconvolution of the resulting color image was demonstrated.

Efficient storage and classification of color patterns based on integrating interpolation with ANN/SVM

Color images usually have large storage sizes as they are composed of three planes in the raw image format represented with the red, green, and blue components. Traditional color image compression schemes can be used to save the storage size of the color images. Unfortunately, most of these schemes are lossy in nature, which affects the details of color images. This paper presents a different treatment to the color image storage problem depending on the original color image formation process. In the color image formation process, not all the red, green, and blue components of the color images are acquired, simultaneously. Only, one component at each pixel position is acquired and Color Filter Array (CFA) interpolation is used to estimate the other two components using interpolation algorithms like Minimized-Laplacian Residual Interpolation (MLRI) and Linear Interpolation with Laplacian Second Order Correction (LILSOC). We adopt a similar strategy in this paper for reducing the storage sizes of color images by 66.67% of their original sizes. The sensitivity of the pattern recognition process to the proposed color image storage and interpolation strategy is studied in this paper. A cepstral feature extraction algorithm is adopted in this paper for extracting features from the interpolated patterns for further classification. Moreover, two types of classifiers are considered and compared in this paper for the pattern recognition: Artificial Neural Networks (ANNs), and Support Vector Machines (SVMs). Simulation results reveal the success of the proposed strategy for color image storage and interpolation in obtaining high-quality color images in addition to the high Recognition Rates (RR) of color patterns after interpolation. This success encourages the use of the proposed color image storage strategy in storing large volumes of color databases.

Investigating the features of color laser marking process of galvanic chrome plating in order to create a controlled color image formation at given marking

Abstract The article is devoted to the problems of laser marking of metal surfaces. The factors affecting the color formation during laser processing are considered. To assess the degree of influence of the material thermophysical characteristics on the final result, samples with different properties were used: steel and brass. In order to exclude the influence of other factors on the result, besides the material characteristics, the samples were chrome-plated to obtain the same thickness of the chromium layer. Samples were processed with the same laser parameters and the same marking modes. The results of the experiment showed the formation of various colors on the treated surface, which proves the influence of the thermophysical characteristics of the material being processed on the formation of the color gamma during laser processing.

Color difference amplification between gold nanoparticles in colorimetric analysis with actively controlled multiband illumination.

Spectral chemical sensing with digital color analysis by using consumer imaging devices could potentially revolutionize personalized healthcare. However, samples with small spectral variations often cannot be differentiated in color due to the nonlinearity of color appearance. In this study, we address this problem by exploiting the color image formation mechanism in digital photography. A close examination of the color image processing pipeline emphasizes that although the color can be represented digitally, it is still a reproducible subjective perception rather than a measurable physical property. That makes it possible to physically manage the color appearance of a nonradiative specimen through engineered illumination. By using scattering light imaging of gold nanoparticles (GNPs) as a model system, we demonstrated via simulation that enlarged color difference between spectrally close samples could be achieved with actively controlled illumination of multiple narrow-band light sources. Experimentally, darkfield imaging results indicate that color separation of single GNPs with various sizes can be significantly improved and the detection limit of GNP aggregation-based colorimetric assays can be much reduced when the conventional spectrally continuous white light was replaced with three independently intensity-controlled laser beams, even though the laser lines were uncorrelated with the LSPR maxima of the GNPs. With low-cost narrow-band light sources widely available today, this actively controlled illumination strategy could be utilized to replace the spectrometer in many spectral sensing applications.

A new model system for studying excited states of dye aggregates of photographic color paper

As a new model system of dye-containing oil droplet of color paper, the dispersion of dye-containing oil droplet in water was successfully prepared by reprecipitation method, and was used for the analysis of photo-excited states of dyes used for color image formation in silver halide color photography. This model was applied to analysis of photo-excited states of yellow dye aggregates of 1,1-dioxo-1,2,4-benzothiadiazine series. It was found that the lightfastness of the yellow dye of this series is controlled by the degree of aggregation and the lifetime of S 1 state of the aggregate. Based on the finding, we have succeeded in improvement of lightfastness of the dye by sterically hindering the aggregation and reducing the lifetime of the excited state.

The role of oxidation states in laser light generation, color image formation and adsorbate–substrate interactions. Comparative study of FA:Tl +1, FB:Tl +1, FA:Tl +3 and FB:Tl +3 color centers at the (1 0 0) and (1 1 0) surfaces of AgBr crystal

The oxidation states of thallium in F A and F B color centers at the low coordination (1 0 0) and (1 1 0) surfaces of AgBr play important roles in laser light generation, color image formation, and adsorbate–substrate interactions. The color center potentials at these surfaces are investigated by using quantum mechanical ab initio methods. Quantum clusters of variable sizes were embedded in the simulated Coulomb fields that closely approximate the Madelung fields of the host surfaces, and ions that were the nearest neighbors to the F A and F B defect sites were allowed to relax to equilibrium. The calculated Stokes shifts suggest that laser light generation is sensitive to the simultaneous effects of the oxidation state of thallium, the coordination number of the surface ion, and the choice of the basis set centered on the anion vacancy. An attempt has been made to explain these effects in terms of Madelung potential, electron affinity, optical–optical conversion efficiency, and adsorbate–substrate electrostatic potentials. All relaxed excited states of the defect containing surfaces were deep below the lower edges of the conduction bands of the ground-state defect-free surfaces, suggesting that the title color centers are suitable laser defects. The dependence of the orientational destruction, recording sensitivity and exciton (energy) transfer on the oxidation state of thallium and the coordination number of the surface ion is clarified. The Glasner–Tompkins empirical rule is generalized to include the oxidation state of the impurity cation and the coordination number of the surface ion. As far as color image formation is concerned, the supersensitizer was found to increase the sensitizing capabilities of two primary dyes in the excited states by increasing the relative yield of quantum efficiency. The Tl +3 surfaces of AgBr are significantly more sensitive than the corresponding Tl +1 surfaces. On the basis of quasi Fermi levels, the difference in the sensitizing capabilites between the examined dyes in the excited states is determined. The adsorbate–substrate interactions were found to be dependent on the oxidation state of the impurity cation and on the electronegativity of the adatom.

Ab initio defect based model for laser light generation and color image formation at the flat, edge and corner surfaces of AgBr: F A1:Cs + and F A2:Li +

The F A1:Cs + and F A2:Li + color centers at the flat, edge and corner surfaces of AgBr play important roles in laser light generation and color image formation. These two applications are investigated simultaneously by using quantum mechanical ab initio methods. As far as laser light generation is concerned, the calculated Stokes shifts suggest that laser activity is sensitive to the simultaneous effects of the vibrational coupling mode, the impurity cation, the coordination number of the surface ion, and the choice of the basis set centered on the anion vacancy. The F A1:Cs + and F A2:Li + color centers are suitable laser defects. The dependence of orientational destruction, recording sensitivity and exciton (energy) transfer on the impurity cation and the coordination number of the surface ion is clarified. The Glasner–Tompkins empirical rule is generalized to include the impurity cation and the coordination number of the surface ion. As far as color image formation is concerned, the supersensitizer was found to increase the sensitizing capabilities of two primary dyes in the excited states. Color image formation was found to be sensitive to the coordination number of the surface ion and the type of the impurity cation. On the basis of quasi Fermi levels, the difference in the sensitizing capabilities between the examined dyes in the excited states was determined.

Theoretical modeling of laser light generation and color image formation: FA1:Tl+ and FA2:Ga+ color centers at the low coordination (100) and (110) surfaces of AgCl and AgBr

Abstract The FA1:Tl+ and FA2:Ga+ color centers at the low coordination (1 0 0) and (1 1 0) surfaces of AgCl and AgBr play important roles in laser light generation and color image formation. Double-well potentials at these surfaces are investigated by using quantum mechanical ab initio methods. Quantum clusters of variable sizes were embedded in the simulated Coulomb fields that closely approximate the Madelung fields of the host surfaces, and ions that were the nearest neighbors to the FA-defect site were allowed to relax to equilibrium. The calculated Stokes shifts suggest that laser light generation is sensitive to the simultaneous effects of the vibrational coupling mode, the impurity cation, the coordination number of the surface ion, the lattice anion, and the choice of the basis set centered on the anion vacancy. An attempt has been made to explain these effects in terms of Madelung potential, electron affinity and optical–optical conversion efficiency. All relaxed excited states of the defect-containing surfaces were deep below the lower edges of the conduction bands of the ground state defect-free surfaces, suggesting that the FA1:Tl+ and FA2:Ga+-centers are suitable laser defects. The dependence of orientational destruction, recording sensitivity and exciton (energy) transfer on the impurity cation, the coordination number of the surface ion, and the type of the lattice anion is clarified. The Glasner–Tompkins empirical rule is generalized to include the impurity cation and the coordination number of the surface ion. As far as color image formation is concerned, the supersensitizer was found to increase the sensitizing capabilities of two primary dyes in the excited states by increasing the relative yield of quantum efficiency. The (1 1 0) surfaces of AgBr and AgCl were more sensitive than the corresponding (1 0 0) surfaces, and AgBr thin film was found to be more sensitive than that of AgCl. On the basis of quasi-Fermi levels, the difference in the sensitizing capabilities between the examined dyes in the excited states was determined.

THE ROLE OF OXIDATION STATES IN LASER LIGHT GENERATION AND COLOR IMAGE FORMATION (II) ANAB INITIOSTUDY OF FA:Hg+AND FA:Hg++COLOR CENTERS AT THE LOW COORDINATION (100) AND (110) SURFACES OFAgBrCRYSTAL

The oxidation states of mercury in FA: Hg+and FA: Hg++color centers at the low coordination (100) and (110) surfaces of AgBr play important roles in laser light generation and color image formation. Two simultaneous potentials at these surfaces were investigated by using quantum mechanical ab initio methods. Quantum clusters of variable sizes were embedded in the simulated Coulomb fields that closely approximate the Madelung fields of the host surfaces, and ions that were the nearest neighbors to the FA– defect site were allowed to relax to equilibrium. The calculated Stokes shifts suggest that laser light generation is sensitive to the simultaneous effects of the oxidation state of mercury, the coordination number of the surface ion, and the choice of the basis set centered on the anion vacancy. An attempt has been made to explain these effects in terms of Madelung potential, electron affinity and optical–optical conversion efficiency. All relaxed excited states of the defect-containing surfaces were deep below the lower edges of the conduction bands of the ground state defect-free surfaces, suggesting that the FA: Hg+and FA: Hg++centers are suitable laser defects. The dependence of the orientational destruction, recording sensitivity and exciton (energy) transfer on the oxidation state of mercury and the coordination number of the surface ion on is clarified. The Glasner–Tompkins empirical rule is generalized to include the oxidation state of the impurity cation and the coordination number of the surface ion. As far as color image formation is concerned, the supersensitizer was found to increase the sensitizing capabilities of two primary dyes in the excited states by increasing the relative yield of quantum efficiency. The Hg++surfaces of AgBr are significantly more sensitive than the corresponding surfaces. On the basis of quasi Fermi levels, the difference in the sensitizing capabilities between the examined dyes in the excited states is determined.

The role of type II FB (I):Tl+ defect in laser light generation and color image formation at the low coordination surface sites of AgBr: ab initio calculations

Abstract The role of type II F B (I):Tl + color center at low coordination surface sites of AgBr thin films in providing tunable laser activity and photographic sensitization is examined. The double-well potential at this site is investigated using ab initio molecular electronic structure calculations. Clusters of variable sizes were embedded in simulated Coulomb fields that closely approximate the Madelung fields of the host surfaces, and ions that are the nearest neighbors to the F B defect site were allowed to relax to equilibrium in each case. The calculated Stokes shifted optical transition bands suggest that laser activity is relatively weak and fades quickly as the coordination number of the surface ions decreases from 5 (flat) to 4 (edge) to 3 (corner). An attempt has been made to explain these results in terms of Madelung potentials and optical–optical conversion efficiencies. All relaxed excited states of the defect containing surfaces were deep below the lower edges of the conduction bands of the ground-state defect-free surfaces indicating that type II F B (I):Tl + is suitable laser defect. The probability of orientational destruction of the two centers, attributed to the assumed saddle point ion configurations along the 〈1 1 0〉 axis, was found to decrease as the coordination number of the surface ions decreases. The possibility of exciton (energy) transfer between sites of different coordination numbers was clarified. The Glasner–Tompkins empirical relation was generalized to include type II F B (I):Tl + doped surfaces. As far as photographic sensitization is concerned, a supersensitizer increases the sensitizing capabilities of the two examined dye molecules by increasing the relative yield of quantum efficiency Φ . F A sensitizes the low coordination surface sites of the defect free AgBr by lowering the bottoms of the conduction bands. The difference in the sensitizing capabilities between the two examined dyes was estimated by calculating the quasi Fermi levels.

Theoretical study of laser light generation and color image formation:FA1:Cs+andFA2:Li+centers at the low coordination (100) and (110) surfaces of AgCl and AgBr

AbstractTheFA1:Cs+andFA2:Li+color centers at the low coordination (100) and (110) surfaces of AgCl and AgBr play important roles in laser light generation and color image formation. Double‐well potentials at these surfaces are investigated by using ab initio calculations. Quantum clusters were embedded in the simulated Coulomb fields that closely approximate the Madelung fields of the host surfaces, and ions that are the nearest neighbors to theFA− defect site are allowed to relax to equilibrium. The calculated Stokes shifts suggest that laser light generation is sensitive to the simultaneous effects of the vibrational coupling mode, the impurity cation, the coordination number of the surface ion, the lattice anion, and the choice of the basis set centered on the anion vacancy. An attempt has been made to explain these effects in terms of Madelung potential, electron affinity, and optical–optical conversion efficiency. All relaxed excited states of the defect‐containing surfaces are deep below the lower edges of the conduction bands of the ground‐state defect‐free surfaces, suggesting that theFA(I):Cs+andFA(II):Li+centers are suitable laser defects. The dependence of orientational destruction, recording sensitivity, and exciton (energy) transfer on the empty cation; the coordination number of the surface ion; and the lattice anion is clarified. The Glasner–Tompkins empirical rule was generalized to include the impurity cation and the coordination number of the surface ion. As far as color image formation is concerned, the supersensitizer was found to increase the sensitizing capabilities of two primary dyes in the excited states by increasing the relative yield of quantum efficiency. The (110) surfaces of AgBr and AgCl were more sensitive than the corresponding (100) surfaces, and AgBr thin film was found to be more sensitive than that of AgCl. On the basis of quasi‐Fermi levels, the difference in the sensitizing capabilities between the examined dyes in the excited states is determined. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005

FA1:La2+ and FA2:Sc2+ color center lasers and color image sensitization at the low coordination (001) surface of AgBr by ab initio calculations

Abstract The twofold potentials of F A1 :La 2+ and F A2 :Sc 2+ color centers at the low coordination (0 0 1) surface of AgBr play important roles in providing tunable laser oscillation and color image sensitization. Double well-potentials at these sites are investigated by using ab initio methods of molecular electronic structure calculations. F A1 :La 2+ and F A2 :Sc 2+ defect containing clusters were embedded in the simulated Coulomb field that closely approximates the Madelung field of the host surface, and the ions that are the nearest neighbors to the F -site are allowed to relax to equilibrium. As far as color center lasers are concerned, the calculated Stokes shifted optical transition bands suggest that the F A2 :Sc 2+ center is more laser active than the F A1 :La 2+ center. An attempt has been made to explain this result on the basis of size of the impurity cation and optical–optical conversion efficiencies. All relaxed excited states of the defect containing surfaces are deep below the lower edge of the conduction band of the ground state defect-free surface implying that both of F A1 :La 2+ and F A2 :Sc 2+ centers are suitable laser defects. The probabilities of orientational destruction of the two centers, which are attributed to the assumed relaxed excited state saddle-point ion configurations along the 〈1 1 0〉 axis, have been found to be approximately identical. Equivalent recording sensitivities are expected from both centers. The F A1 :La 2+ and F A2 :Sc 2+ defect formation energies are calculated, and the Glasner–Tompkins empirical relation was generalized to include the dopant cations. As far as color image formation is concerned, F A1 :La 2+ and F A2 :Sc 2+ color centers increase the sensitizing capabilities of primary dyes and the effect of supersensitizers by lowering the bottom of conduction band of the silver bromide surface. The supersensitizer increases the sensitizing capability of a primary dye in the excited state by increasing the relative yield of quantum efficiency. On the basis of quasi-Fermi levels, the difference in the sensitizing capabilities between the examined dyes in the excited states are determined.

The role of FA:K+ and FA:Na+ defects in laser light generation and color image formation at the (100) and (110) surface sites of AgCl and AgBr.

FA:K+ and FA:Na+ color centers at the low coordination (100) and (110) surface sites of AgCl and AgBr thin films play important roles in providing tunable laser oscillation and color image sensitization. Double-well potentials at these sites are investigated using ab initio molecular electronic structure calculations. Quantum clusters were embedded in simulated Coulomb fields that closely approximate the Madelung fields of the host surfaces, and ions that are the nearest neighbors to the FA defect site were allowed to relax to equilibrium. The calculated Stokes shifted optical transition bands suggest that laser light generation is sensitive to (i) the lattice anion, (ii) the coordination number of surface ions, (iii) the dopant cation, (iv) the vibrational coupling mode, and (v) the choice of the basis set centered on the anion vacancy. An attempt has been made to explain these results in terms of Madelung potentials, electron affinities and optical–optical conversion efficiencies. All relaxed excited states of the defect-containing surfaces were deep below the lower edges of the conduction bands of the ground state defect-free surfaces, suggesting that FA:K+ and FA:Na+ are suitable laser defects. The probability of orientational destruction of the two centers, attributed to the assumed saddle point ion configurations along the 〈110〉 axis, was found to be dependent on the lattice anion, the coordination number of surface ions, and the dopant cation. For optical memories, a high recording sensitivity was assigned to FA:Na+ relative to FA:K+, to the (110) surface relative to the (100) surface, and to AgCl relative to AgBr. The dependence of exciton (energy) transfer on the lattice anion, the coordination number of surface ions, and the dopant cation was clarified. The Glasner–Tompkins empirical rule was generalized to include the surface coordination number and the dopant cation in addition to the lattice anion. As far as color image formation is concerned, the examined supersensitizer was found to increase the sensitizing capabilities of two primary dyes in the excited states by increasing the relative yield of quantum efficiency. The (110) surfaces of AgBr and AgCl were more sensitive than the corresponding (100) surfaces, and the AgBr thin film was found to be more sensitive than that of AgCl. Based on quasi Fermi levels, the difference in the sensitizing capabilities between the examined dyes in the excited states was determined.

Edge-adaptive color interpolation algorithm for progressive scan charge-coupled device image sensors

Yonsei UniversityDepartment of Electrical & ElectronicEngineering134 Shinchon, Seodaemun-KuSeoul, KoreaE-mail: mkang@yonsei.ac.krAbstract. The color interpolation scheme can play an important role inovercoming the physical limitation of CCD image sensors and in increas-ing the resolution of color signals, while most conventional approachesresult in blurred edges and false color artifacts. We propose an improvededge-adaptive color interpolation scheme for a progressive scan CCDimage sensor with an RGB color filter array. The proposed edge indicatorfunction utilizes not only the within-channel correlation, but also thecross-channel correlation, and reflects the edge characteristics of an im-age adaptively. The color components unavailable at each channel areinterpolated along the edge direction, not across the edges, so that alias-ing artifacts are suppressed. Furthermore, we eliminate false color arti-facts resulting from the color image formation model in the edge-adaptive color interpolation scheme by adopting the switching algorithmbased on the color edge detection. Simulation results of the proposedalgorithm indicate that the improved edge-adaptive color interpolationscheme produces results that are quantitatively better and visually morepleasing than those achieved by conventional approaches.

High definition color interpolation scheme for progressive scan CCD image sensor

A color interpolation scheme for a progressive scan CCD image sensor with a RGB color filter array is required to overcome the physical limitation of the CCD image sensor and to increase the resolution of color signals. Most conventional approaches result in blurred edges and false color artifacts. In this paper, we propose an improved edge-adaptive color interpolation scheme for a progressive scan CCD image sensor. The proposed edge indicator function uses not only the within-channel correlation but also the cross-channel correlation, and reflects the edge characteristics in an image adaptively. The color components unavailable at each channel are interpolated along the edge direction, not across the edges, so that aliasing artifacts are suppressed. Furthermore, we eliminated false color artifacts resulting from the color image formation model in the edge-adaptive color interpolation scheme by adopting the switching algorithm that is based on the color edge detection. Simulation results of the proposed algorithm indicate that the improved edge-adaptive color interpolation scheme produces better quantitative and visually pleasing results than other conventional approaches.

Demosaicing: image reconstruction from color CCD samples

A simplified color image formation model is used to construct an algorithm for image reconstruction from CCD sensors samples. The proposed method involves two successive steps. The first is motivated by Cok's template matching technique, while the second step uses steerable inverse diffusion in color. Classical linear signal processing techniques tend to oversmooth the image and result in noticeable color artifacts along edges and sharp features. The question is how should the different color channels support each other to form the best possible reconstruction. Our answer is to let the edges support the color information, and the color channels support the edges, and thereby achieve better perceptual results than those that are bounded by the sampling theoretical limit.

Solution for the Retransfer Mechanism of Color Imaging Process

In electrophotographic process, the system to transfer several times is used for the color image formation. The phenomenon that toner images has formed already on the recording medium returns to photoconductive drum was confirmed, and it is clear that this phenomenon is found conspicuously on the photoconductive drum where the toner does not exist. The electrification charge inside of toner image on recording medium is uneven, and this is thought so that an electric field formed at the toner transfer end point works to the direction that seems to return one part of toner on recording medium to photoconductive drum. In this work we theoretically analyze the electrification voltage inside of toner image at the end point of toner transfer, it is clear the reason why toner return to photoconductive.

Color Image Formation Using Polymer-Dispersed Cholesteric Liquid Crystal

A color image has been successfully formed on a stack of polymer-dispersed cholesteric (chiral nematic) liquid crystal (PDCLC) films. A combined image through the stack of PDCLC films that reflect at different wavelengths was simultaneously formed by spot heating using an infrared laser beam while controlling the electric field applied to each film. The image is written by an electric-field-assisted thermal process, in which, after partial heating, regions cooled with a field become selectively reflective and regions cooled without a field become transparent. A combined image on a two-layer stack of PDCLC films showed the feasibility of color image formation. A memory effect maintains the image for a long period without any holding techniques, and the image can easily be changed, hence, the stack of PDCLC films can be used repeatedly.