Authenticable Luminescent Color Halftone Images
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Solution Overview
Problem
Existing methods for creating color images with luminescent inks are limited in authenticity verification and aesthetics, particularly in high-throughput and large-size printing systems, and struggle to combine classical and daylight luminescent inks effectively for secure and attractive visual effects.
Innovation Solution
A computer-based method using a luminescent set of inks comprising at least one daylight luminescent ink, which involves gamut mapping and color separation to create authenticable, multi-ink luminescent color halftone images visible under daylight, utilizing gamut expansion and reduction operations to enhance chroma and lightness, and incorporating hidden messages revealed under different illuminants for authentication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If daylight luminescent inks are used to create color images, then the visual attractiveness and chroma are improved, but the ability to prevent unauthorized reproduction is reduced
Solution Approach 1:
The color image is segmented into multiple ink layers with distinct luminescent properties. Some layers contain inks that luminesce under UV light while others contain inks visible only under visible light, creating separate authenticatable components that can be verified independently
Solution Approach 2:
Different regions of the image use different ink compositions with specific luminescent characteristics. Certain areas contain UV-reactive inks while others contain visible-light inks, allowing localized authentication features that enhance security without compromising overall visual quality
2Productivity
If classical printing methods are used, then high-throughput and large-size printing are achieved, but the visual enhancement and security features are reduced
Solution Approach 1:
The printing system is designed to handle multiple ink types (UV-reactive and visible-light inks) using standard printing infrastructure. The method integrates security feature creation into conventional high-throughput printing processes, allowing classical printing systems to produce enhanced images with authentication capabilities
3Adaptability or versatility
If multiple luminescent inks are combined, then the extended gamut is achieved, but the device complexity increases
Solution Approach 1:
The system dynamically selects and combines different luminescent ink sets based on the authentication requirements and desired visual effects. The printing process can adjust ink layer compositions and luminescent properties to achieve extended gamut while managing system complexity through adaptive configuration
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enables the creation of visually enhanced, authenticable color images with extended gamuts, preventing unauthorized reproduction and ensuring high-quality faithful color reproductions, especially for valuable items and documents, by leveraging the unique properties of daylight luminescent inks.
Implementation Method 1
daylight luminescent inks produce, when seen under daylight, saturated and intense colors since part of the energy absorbed at excitation wavelengths within the UV and the visible wavelength ranges is reemitted by luminescence within the visible wavelength range
Implementation Method 2
The term 'luminescence' encompasses both the de-excitation of molecules by fluorescent emission
Implementation Method 3
since for most daylight luminescent inks, energy is also absorbed in the UV excitation wavelength range, daylight luminescent inks form, thanks to their emission spectra, also visible colors, when seen under a UV illumination (also called 'black light')
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3A~3B
AI summary
The present invention enables creating authenticable multi-ink luminescent continuous tone color halftone images offering means of verifying their authenticity. The invented luminescent color halftone image synthesizing techniques enable increasing the attractiveness and aesthetics of color images. The invention relies on daylight luminescent inks, color prediction models for daylight luminescent halftones, color gamuts of luminescent and non-luminescent inks, color separation into luminescent and non-luminescent ink layers, mapping of input gamuts into a luminescent target gamuts by gamut reduction and/or expansion strategies, and luminescent color halftone image generation. The basic authentication is performed by examining the excitation trace image of the synthesized luminescent color halftone image under an illuminant active within its excitation wavelength range. Further authentication means include hiding messages under one or several different illuminants as well as hiding message with different sets of luminescent inks. Hidden messages are recovered under illuminants different from their reference illuminant.