Edge Enhancement System Using Gradient Analysis to Reduce Noise Artifacts

Solution Overview

Problem

Existing edge enhancement methods are sensitive to noise, leading to 'striped noise' artifacts between narrow edges, which affects the quality of video image sharpness and depth perception.

Innovation Solution

A system and method that perform vertical and horizontal edge enhancements using local gradient analysis to generate a local gradient direction and magnitude, which are then used to mix the enhanced outputs adaptively, reducing noise sensitivity and improving image sharpness by steepening edge transitions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If turning point detection is used to determine maximum and minimum pixels, then edge enhancement can be achieved, but noise sensitivity increases and striped noise artifacts are created

Engineering Contradiction:

Improveedge enhancement precisionVSAvoidnoise sensitivity

Core Design Contradiction:

Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The patent changes the detection parameter from turning points (second derivative) to zero-crossing points of the first derivative. This parameter change fundamentally alters how edges are detected, moving from a method that is sensitive to noise to one that is more robust. The zero-crossing detection of the first derivative provides a more stable edge detection mechanism that does not amplify noise as severely as turning point detection.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent substitutes the mechanical turning point detection mechanism with a zero-crossing detection mechanism. Instead of relying on the second derivative to find turning points, the system uses the first derivative to find zero-crossing points, which represent edges. This substitution replaces a noise-sensitive mechanical detection process with a more robust alternative that maintains edge detection capability while reducing noise amplification.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Manufacturing precision

If turning point detection is used to determine maximum and minimum pixels, then edge enhancement can be achieved, but striped noise artifacts appear between narrow edges

Engineering Contradiction:

Improveedge enhancement precisionVSAvoidstriped noise artifacts

Core Design Contradiction:

Manufacturing precisionVSObject-generated harmful factors

Solution Approach 1:

The patent changes the detection parameter from turning points (second derivative) to zero-crossing points of the first derivative. This parameter change fundamentally alters how edges are detected, moving from a method that is sensitive to noise to one that is more robust. The zero-crossing detection of the first derivative provides a more stable edge detection mechanism that does not amplify noise as severely as turning point detection.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent substitutes the mechanical turning point detection mechanism with a zero-crossing detection mechanism. Instead of relying on the second derivative to find turning points, the system uses the first derivative to find zero-crossing points, which represent edges. This substitution replaces a noise-sensitive mechanical detection process with a more robust alternative that maintains edge detection capability while reducing noise amplification.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Manufacturing precision

If vertical and horizontal edge enhancements are performed separately, then comprehensive edge enhancement is achieved, but device complexity increases

Engineering Contradiction:

Improveedge enhancement completenessVSAvoidprocessing unit complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent segments the edge enhancement process into independent vertical and horizontal processing paths. Each path can be processed simultaneously using separate processing units or pipelines. This segmentation allows for parallel processing, which maintains comprehensive edge enhancement while managing complexity through modular architecture. The vertical and horizontal enhancements are performed as separate operations that can be optimized independently.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent merges the vertical and horizontal enhancement results through a mixing mechanism that combines both processing paths. By merging the results of the separate vertical and horizontal enhancements, the system achieves comprehensive edge enhancement while managing complexity through efficient resource utilization. The mixing process integrates the benefits of both directional enhancements without requiring completely separate processing systems.

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentUS8659618B2Noise-robust edge enhancement system and method for improved image sharpness

Publication Date: 2014.02.25 STMICROELECTRONICS ASIA PACIFIC PTE

AI summary

A system for edge enhancement includes an input unit to receive an input signal Yin, a vertical enhancement unit to perform a vertical enhancement of an edge of the input signal Yin to generate an output YEV, and a horizontal enhancement unit to perform a horizontal enhancement of the edge of the input signal Yin to generate an output YEH. The system also includes a local gradient analysis unit to generate a local gradient direction GradDir and a local gradient magnitude GradMag based at least partly upon the input signal Yin, and a mixer to generate an output Yout by mixing the output YEV with the output YEH using the local gradient direction GradDir. The system further includes an output unit to output the output Yout.