Image Processing Circuit Sharpness Enhancement via Luminance Variation

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Solution Overview

Problem

Conventional linear high pass filters either damage image texture at high frequencies or produce thickened objects with ringing artifacts at low frequencies, affecting image sharpness and display quality.

Innovation Solution

An image processing circuit comprising a receiving circuit, a sharpness processing circuit, and a luminance variation processing circuit that performs high-pass filtering and calculates high frequency component differences between pixels and their neighbors to generate auxiliary data, which is combined with processed data to produce an output image.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the frequency of the linear HPF is increased (or the length of the HPF is shortened), then the image sharpness is improved, but the original texture of the image is damaged and edge luminance becomes higher than central luminance

Engineering Contradiction:

Improveimage sharpnessVSAvoidtexture damage and edge luminance distortion

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent applies local quality by differentiating processing for different regions: edge pixels receive different treatment than central pixels. The luminance variation processing circuit identifies edge pixels and applies selective processing to prevent edge luminance distortion while maintaining sharpness enhancement for all pixels through the high-pass filtering operation.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent applies preliminary anti-action by calculating the luminance variation of edge pixels before final image generation. This allows the system to pre-identify and compensate for potential edge luminance distortion caused by high-pass filtering, preventing the harmful effect before it manifests in the output image.

Inventive Principle:

Principle #9Preliminary anti-action

2Measurement precision

If the frequency of the linear HPF is decreased (or the length of the HPF is lengthened), then the image sharpness is improved, but the sharpened object becomes thicker and ringing artifacts are formed at the edge

Engineering Contradiction:

Improveimage sharpnessVSAvoidobject thickening and ringing artifacts

Core Design Contradiction:

Measurement precisionVSObject-generated harmful factors

Solution Approach 1:

The patent applies local quality by differentiating processing for different regions: edge pixels receive different treatment than central pixels. The luminance variation processing circuit identifies edge pixels and applies selective processing to prevent ringing artifacts and object thickening while maintaining sharpness enhancement for all pixels through the high-pass filtering operation.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent converts the harmful effect of luminance variation at edges into a beneficial correction process. By calculating and analyzing luminance variation, the system identifies areas prone to ringing artifacts and object thickening, then applies corrective processing that eliminates these artifacts while preserving the desired sharpness enhancement.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Measurement precision

If a high-pass filtering operation is applied to enhance sharpness, then the image clarity is improved, but the display quality deteriorates due to artifacts and distortion

Engineering Contradiction:

Improveimage clarityVSAvoiddisplay quality

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent applies feedback by using the calculated luminance variation information to adjust the processing of edge pixels. The luminance variation processing circuit provides feedback about edge characteristics, allowing the output circuit to compensate for potential artifacts and distortion, thereby maintaining both clarity enhancement and display quality.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent introduces an intermediary processing step (luminance variation processing) between the high-pass filtering operation and the final output. This intermediary circuit analyzes edge characteristics and prepares correction data that mediates between the sharpness enhancement goal and the quality preservation requirement.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS11379956B2Image processing circuit and associated image processing method

Publication Date: 2022.07.05 REALTEK SEMICON CORP

AI summary

The present invention discloses an image processing circuit, wherein the image processing circuit comprises a receiving circuit, a sharpness processing circuit, a luminance variation processing circuit and an output circuit. In the operations of the image processing circuit, the receiving circuit is configured to receive image data; the sharpness processing circuit is configured to perform a high-pass filtering operation on the image data to generate processed image data; the luminance variation processing is configured to determine a high frequency component of each pixel within the image data, and for each pixel, the luminance variation processing circuit is configured to calculate a difference between high frequency components of the pixel and neighboring pixel(s) to generate auxiliary image data; and the output circuit is configured to generate output image according to the processed image data and the auxiliary image data.