Prediction and Inverse Design of Structural Colors of Nanoparticle Systems via Deep Neural Network

Noniridescent and nonfading structural colors generated from metallic and dielectric nanoparticles with extraordinary optical properties hold great promise in applications such as image display, color printing, and information security. Yet, due to the strong wavelength dependence of optical constants and the radiation pattern, it is difficult and time-consuming to design nanoparticles with the desired hue, saturation, and brightness. Herein, we combined the Monte Carlo and Mie scattering simulations and a bidirectional neural network (BNN) to improve the design of gold nanoparticles’ structural colors. The optical simulations provided a dataset including color properties and geometric parameters of gold nanoparticle systems, while the BNN was proposed to accurately predict the structural colors of gold nanoparticle systems and inversely design the geometric parameters for the desired colors. Taking the human chromatic discrimination ability as a criterion, our proposed approach achieved a high accuracy of 99.83% on the predicted colors and 98.5% on the designed geometric parameters. This work provides a general method to accurately and efficiently design the structural colors of nanoparticle systems, which can be exploited in a variety of applications and contribute to the development of advanced optical materials.

A Legorization method based on 3D color printing trajectory

In this paper, a Legorization method which can reconstruct LEGO model with complex internal and external structures from 3D color printing trajectory is proposed. Different from voxelization methods, by combining advanced adaptive slicing algorithm with building “high-resolution” regions with thin plates, the reconstruction accuracy of initial LEGO units can be guaranteed. Furthermore, the tree structure is employed for automatically generating support structures which can be converted into LEGO support structures. By adopting split assembly appropriately and implementing combination of these parts accurately, the reducing supporting structures can be further simplified. In order to optimize the Legorization scheme, a machine learning method is used to guarantee the quality and efficiency of the reconstruction work. Complex LEGO models are provided to demonstrate the effectiveness of the proposed method.

Statistical evaluation of a Color Managed Digital Printing Workflow (CMDPW) consistency [4th C of CMW]

The purpose of this applied research was to determine the Color Managed Digital Printing Workflow (CMDPW) consistency (4th C of the color management) over a period of time [100 days, (N = 100)]. The quality of digital color printing is determined by these influential factors: screening method applied, type of printing process, calibration method, device profile, ink (dry-toner or liquid-toner), printer resolution and the substrate (paper). For this research, only the color printing attributes such as the overall average color deviation [ACD, ΔE (2000)] and the solid ink density (SID) were analyzed to examine the CMDPW process consistency in a day-to- day digital printing operation. These are the color attributes which are monitored and managed for quality accuracy during the printing. Printed colors of the random sample size (n = 80) were measured against the GRACoL2013 standards to derive the colorimetric/densitometric values. Reference colorimetric values used in the analysis were the threshold deviations (acceptable color deviations) as outlined in the ISO12647-7 standards (GRACoL2013). A control charts analysis was applied for further determining the process (CMDPW) SID and ACD variation. The data collected were run through multiple software applications (MS-Excel/SPSS/Minitab) to apply various statistical methods. Analyzed data from the experiment revealed that the printed colorimetric values were in match (aligned) with the GRACoL 2013 (reference/target). Since the SID values of CMYK colors were in control throughout the process, this enabled the CMDPW to produce consistent acceptable color deviation (Average Printed ΔE (2000) = 2.978; SD = 0.437; Acceptable Threshold color deviation is ΔE (2000) ≤ 3.00).

Automatic Unfolding of CityGML Buildings to Paper Models

3D city models are mainly viewed on computer screens, but many municipalities also use 3D printing to make urban planning tangible. Since 3D color printing is still comparatively expensive and the colors often fade over time, many of these models are monochrome. Here, color textured paper models offer an inexpensive and under-appreciated alternative. In this paper, a greedy algorithm adapted to CityGML building models is presented, which creates print templates for such paper models. These 2D layouts consist of cut edges and fold edges that bound polygons of a building. The polygons can be textured or left blank depending on the existence of CityGML textures. Glue tabs are attached to cut edges. In addition to the haptic 3D visualization, the quality of the 3D models can sometimes be better assessed on the basis of the print templates than from a perspective projection. The unfolding procedure was applied to parts of the freely available CityGML model of Berlin as well as to parts of models of the cities of Dortmund and Krefeld.

Ablation-Free Laser Printing of Structural Colors in Reflection at 25,000 DPI

Using direct femtosecond laser patterning of metal-insulator-metal (MIM) sandwich designed to support Fabry-Perot mode in the visible spectral range we demonstrate new practically relevant strategy for high-resolution color printing. Irradiation of the MIM sandwich by tightly focused laser pulses allows to produce unique 3D surface nanostructures – hollow nanobumps and nanojets - locally modulating surface reflectivity. Laser processing parameters control the 3D shape of such nanostructures allowing to gradually tune the reflected color from reddish brown to pure green. Up-scalable ablation-free laser fabrication method paves the way towards various applications ranging from large-scale structural color printing to optical sensors and security labeling at a lateral resolution of 25,000 dots per inch.

Color printing on pre-colored textiles

Managing color on a particular imaging system is a wellunderstood challenge with a wealth of existing models, methods and techniques. In the case of printing systems, these tend to operate in the context of a single substrate, where managing color on every additional substrate is approach as a separate, detached problem. While such a mind-set works reasonably well in general, it breaks down when it comes to printing onto precolored textiles, such as pre-dyed fabrics. The present paper therefore introduces a family of approaches that support the use of multiple pre-colored textiles on a given printing system that also allow for a balance between characterization effort and color match accuracy. This, in turn provides solutions that can fit a variety of practical working patterns to maximize overall efficiency and performance.

Mapping Travel

More often than not, readers of travel narratives expect to find one or several maps showing, as English privateer William Dampier wrote, “the Course of the Voyage,” that is, where the author-traveler went and, implicitly, a sense of what was seen and experienced. Dampier used a now-common cartographic strategy to tell the story from beginning to end as well as focus on significant places on the way by marking the journey with a “pricked” line. Despite the lines’ popularity and present ubiquity, the complex intellectual processes of considering travel as a continuum rather than as a series of stops and of plotting a journey onto a map have attracted relatively little academic attention. Drawing on a thousand years of European travel writing and map-making, this work suggests that in fifteenth-century Europe, maps joined text-based itineraries and on-the-spot directions to guide travelers and accompany reports of land and sea travel. Called in subsequent centuries “route maps,” “itinerary maps,” and “travel maps,” often interchangeably, what are defined here as journey maps added lines of travel. Since their emergence, most journey maps have taken one of two forms: itinerary maps, which connected stages with line segments, and route maps, which tracked unbroken lines between endpoints. In the seventeenth century, journey mapping conventions were codified and incorporated into travel writing and other genres that represented individual travel. With each succeeding generation, journey maps have become increasingly common and complex, responding to changes in forms of transportation, such as air and motor car “flight” and print technology, especially the advent of multi-color printing.

On challenges of arranging a series of etchings as illustrated by Elena Grazhevskaya’s graduate project supervisor – Alexei Popov, honored artist of Russia and associate member of the Russian academy of arts

The article reveals a number of rules regulating the arrangement of a series of two-dimensional images universal both for works of fine art, as well as photography and design. The authors outline the key principles of creating such a series through a thorough description of the working process behind “The Herbs”, a set of five etchings by Elena Grazhevskaya. The aforementioned project was developed as a graduate qualification work at the Academy of Watercolor and Fine Arts of Sergey Andriaka under the supervision of the Honored Artist of the Russian Federation and Associate Member of the Russian Academy of Arts A. B. Popov. The authors of the article discuss the problem of selecting appropriate composition formats and their subsequent mirroring in relation to the centerpiece of the series at its preliminary sketching stage. The article touches upon the question of proper space composition in symmetrical images, i.e. how to convey a similar depth of couple pieces in the series. The fundamental techniques for working with the tonal color scheme are unveiled, namely the simultaneous portrayal of unity and contrast of lights and shadows in the pieces symmetrical to the central one. Furthermore, the paper addresses how to wisely choose a technique optimal for the type of etchings belonging to the series. The concurrent usage of aquatint and etching stroke technique is justified as it allows one to combine detailed object drawing with decorative aquatint painting as a compositionally organizing element. Likewise, the authors delineate the principles for selecting appropriate printing ink, particularly in the light of the use of a painterly “two-color printing effect” (application of a warm-cold effect of one ink in layers of different thickness). The article will be useful for teachers and students of art schools at all levels of education, photographers and designers, as well as anyone who is interested in creating a series of visual art works.