Clear Ink Overcoat for Specular Reflection Coloring Reduction

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Solution Overview

Problem

Existing methods for reducing specular reflection light coloring in images, such as using yellow ink to cover cyan or magenta regions, result in a reduction of color gamut or induce noticeable bronzing phenomena, while overcoating with achromatic color materials leads to varying results depending on the ink amount and type under the achromatic layer.

Innovation Solution

An image processing apparatus and method that uses a clear ink as an achromatic color material, applying it with a randomly varying amount to each pixel to create a layer that reduces comprehensive coloring of specular reflection light by localizing different colorings at each pixel, effectively mixing red, green, and blue to appear white, thus minimizing observed specular reflection light.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If yellow ink is used to cover cyan or magenta regions to reduce bronzing, then bronzing is reduced, but color gamut is reduced

Engineering Contradiction:
ImprovebronzingVSAvoidcolor gamut
Core Design Contradiction:
Object-affected harmful factorsVSQuantity of substance

Solution Approach 1:

The invention changes the parameter of the overcoat ink from colored (yellow) to achromatic (clear), fundamentally altering the approach to reducing bronzing. By using clear ink with minimal coloration instead of yellow ink, the solution reduces bronzing effects while preserving the original color gamut of the printed image, as the clear ink does not introduce additional color constraints.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention uses clear ink as a temporary overcoat layer that serves its purpose of reducing bronzing and then allows the underlying color layers to remain visible. The clear ink acts as a transient element that modifies optical properties without permanently altering the color composition, enabling bronzing reduction while maintaining color fidelity.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

2Quantity of substance

If discharge amount of yellow ink is reduced to maintain color gamut, then color gamut is maintained, but bronzing phenomenon becomes noticeable

Engineering Contradiction:
Improvecolor gamutVSAvoidbronzing
Core Design Contradiction:
Quantity of substanceVSObject-affected harmful factors

Solution Approach 1:

The invention fundamentally changes the parameter of the overcoat ink from colored to achromatic. By using clear ink instead of yellow ink, it provides an alternative mechanism for reducing bronzing that does not require compromising color gamut, thus resolving the trade-off between maintaining color fidelity and reducing bronzing effects.

Inventive Principle:
Principle #35Parameter changes

3Object-affected harmful factors

If achromatic color material is used to overcoat image, then bronzing is reduced, but coloring varies depending on ink amount

Engineering Contradiction:
ImprovebronzingVSAvoidcoloring uniformity
Core Design Contradiction:
Object-affected harmful factorsVSManufacturing precision

Solution Approach 1:

The invention optimizes the parameter of ink amount for the clear overcoat layer, establishing a specific range (5-50% of maximum discharge amount) that balances bronzing reduction with coloring uniformity. This parameter optimization ensures that the clear ink provides sufficient coverage to reduce bronzing while maintaining consistent optical properties across different regions of the printed image.

Inventive Principle:
Principle #35Parameter changes

4Device complexity

If clear ink is discharged in fixed amount to each pixel, then processing is simple, but specular reflection light coloring is not comprehensively reduced

Engineering Contradiction:
Improveprocessing complexityVSAvoidspecular reflection light coloring
Core Design Contradiction:
Device complexityVSObject-affected harmful factors

Solution Approach 1:

The invention applies local quality by varying the clear ink discharge amount according to specific pixel characteristics rather than using a uniform fixed amount. The system determines different ink amounts based on local image properties such as color saturation and specular reflection characteristics, thereby comprehensively reducing bronzing across different regions while adapting to local requirements.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The invention introduces dynamics by making the clear ink discharge amount variable rather than fixed. The ink amount is dynamically adjusted for each pixel based on image analysis, allowing the system to adapt to different local conditions and effectively reduce specular reflection light coloring across the entire image while responding to local variations.

Inventive Principle:
Principle #15Dynamics

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 comprehensively reduces the coloring of specular reflection light by ensuring that each pixel has a unique achromatic color material amount, resulting in a uniform appearance that minimizes the visibility of specular reflection light, maintaining color gamut and preventing bronzing.

Implementation Method 1

Overcoating an image with use of an achromatic color material results in a change in coloring of specular reflection light according to the ink amount of the achromatic color material, since a thin-film interference occurs due to an optical path difference of reflected light between the upper layer and the lower layer of the achromatic color material layer.

Methodology Applied
Scientific EffectThin-film interference: Interference

Implementation Method 2

a phenomenon of coloring of specular reflection light, which is light reflected by the formed image

Methodology Applied
Scientific EffectSpecular reflection: Reflection

Data Source

PatentEP2629978B1Image processing apparatus and image processing method
Publication Date: 2020.04.01 CANON KK
  • EP2629978B1 patent drawingFigure 1
  • EP2629978B1 patent drawingFigure 2
  • EP2629978B1 patent drawingFigure 3

AI summary

An image processing apparatus includes a conversion unit configured to convert image data corresponding to a pixel of interest in an image into color material data corresponding to a color material amount of a chromatic color material, and a generation unit configured to generate color material data corresponding to a color material amount of an achromatic color material at the pixel of interest in such a manner that the color material data corresponding to the color material amount of the achromatic color material at the pixel of interest is different from color material data corresponding to a color material amount of the achromatic color material at a pixel adjacent to the pixel of interest.