Image Sharpening Gain Normalization to Avoid Black Edges

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Solution Overview

Problem

Existing image sharpening methods often result in black edges and reduced image display quality due to the enhancement of high-frequency signals in areas with low intensity, leading to 'dead black' and 'black edges'.

Innovation Solution

An image processing method that normalizes gain information based on local average brightness and determines gain information from three dimensions: local contrast, edge contrast, and texture contrast, to accurately control frequency signals and enhance image clarity without black edges.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If high-frequency signals are enhanced through filtering and adding back to the image, then image clarity and edge enhancement are improved, but black edges and dead black areas occur in low intensity regions

Engineering Contradiction:

Improveimage clarityVSAvoidblack edges

Core Design Contradiction:

Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The patent applies local quality by calculating gain values differently for different regions of the image based on their brightness characteristics. High-gain regions are identified where enhancing high-frequency signals would cause black edges, and these regions are excluded from sharpening processing. This allows the image to have different processing characteristics in different areas, maintaining clarity in appropriate regions while avoiding black edges in low intensity regions.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent changes the gain parameter dynamically based on local image characteristics. By calculating gain values from luminance information and using these to control the sharpening strength in different regions, the system adjusts the processing parameters adaptively. This prevents excessive gain in low intensity areas that would cause black edges, while maintaining sufficient gain in mid to high intensity areas for effective sharpening.

Inventive Principle:

Principle #35Parameter changes

2Device complexity

If gain information is determined solely based on contrast, then processing is simple, but the balance and accuracy of sharpening results deteriorates

Engineering Contradiction:

Improveprocessing complexityVSAvoidsharpening accuracy

Core Design Contradiction:

Device complexityVSManufacturing precision

Solution Approach 1:

The patent adds another dimension to gain calculation by incorporating both contrast information and luminance information. Instead of determining gain solely from contrast (one dimension), the system uses a two-dimensional approach combining contrast and luminance to calculate gain values. This dimensional expansion allows for more accurate gain determination that reflects actual image characteristics, improving sharpening accuracy without excessive complexity.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Data Source

PatentEP4446974B1Image processing method, electronic apparatus and chip

Publication Date: 2026.02.18 BEIJING X RING TECHNOLOGY CO LTD

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AI summary

An image processing method includes: determining (S201) first gain information of an image to be processed based on a contrast of the image to be processed; normalizing (S202) the first gain information based on a local average brightness of the image to be processed to obtain second gain information; and obtaining (S203) target edge information of the image to be processed based on the second gain information, the target edge information being configured for sharpening the image to be processed.