Thermal Transfer Image Data Tone Value Dithering

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Solution Overview

Problem

Existing image display devices using thermal transfer technology suffer from reduced gradation representativeness, as multitone input images are converted into images with fewer tone levels, resulting in discontinuous tone variations and decreased representativeness of continuous tone values in the transferred images.

Innovation Solution

A method for providing thermal transfer image data involves converting multitone input images into images with fewer tone levels based on a predetermined threshold, dithering tone values, and dividing the image into interleaved regions with varying tone value differences to maintain continuous tone variations, thereby preventing degradation of gradation representativeness.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a multitone input image is converted into an image with fewer tone levels for thermal transfer, then the image can be transferred using a transfer ribbon with relief structure, but the representativeness of continuous tone variations is reduced and gradation quality deteriorates

Engineering Contradiction:
Improvetransfer process compatibilityVSAvoidgradation representativeness
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

The image is divided into multiple interleaved regions (e.g., even and odd columns or rows) before tone value conversion. This segmentation allows different tone value assignments in adjacent regions, creating a dithered pattern that preserves continuous tone variation appearance while using fewer actual tone levels in the transfer image

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different tone value differences are applied to different regions of the image. Specifically, low-tone-value regions use larger tone value differences, high-tone-value regions use larger tone value differences, while intermediate-tone-value regions use smaller tone value differences. This local adaptation maintains gradation representativeness across the entire image range

Inventive Principle:
Principle #3Local quality

2Adaptability or versatility

If tone values are reduced to three to four levels for transfer, then thermal transfer with relief structure becomes feasible, but continuous tone variation becomes discontinuous

Engineering Contradiction:
Improvetransfer ribbon compatibilityVSAvoidtone value continuity
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The image is pre-processed by dividing it into interleaved regions and assigning different tone values to adjacent regions before the actual thermal transfer process. This preliminary dithering action ensures that when the image is transferred with limited tone levels, the human visual system perceives continuous tone variation through the dithered pattern rather than discrete steps

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The tone value parameters are strategically adjusted in different regions of the image. By varying the tone value differences based on the local tone value range (smaller differences in intermediate tones, larger differences in low and high tones), the patent maintains the perceptual continuity of gradations while adapting to the limited tone level constraint of the transfer ribbon

Inventive Principle:
Principle #35Parameter changes

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

This approach effectively preserves the representativeness of continuous tone variations in the transferred images, enhancing the visual fidelity of gradations without reducing the image quality, even when using a transfer ribbon with a relief structure.

Implementation Method 1

transferring part of a transfer material layer in a transfer ribbon to an image-receiving layer

Methodology Applied
Scientific EffectThermal transfer: Conduction (thermal)

Data Source

PatentEP3421249B1Thermal transfer image-data creation method, image forming method, and image display device
Publication Date: 2022.10.26 TOPPAN HOLDINGS INC
  • EP3421249B1 patent drawingFigure 1~2
  • EP3421249B1 patent drawingFigure 3~4
  • EP3421249B1 patent drawingFigure 5

AI summary

Thermal transfer image data is used to transfer part of a transfer material layer in a transfer ribbon to an image-receiving layer in an intermediate transfer ribbon to form a plurality of image cells on the intermediate transfer ribbon. A method for providing thermal transfer image data includes converting a multitone input image into a multitone image having fewer different tone values than the input image, based on a predetermined threshold; and dithering respective tone values of the image.