Local Adaptive Contrast Enhancement Using Hardware Lookup Tables

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Solution Overview

Problem

Existing local contrast enhancement techniques in display technologies require significant processor resources for histogram calculations and data movement, leading to inefficiencies and power consumption, and often result in over-sharpening and noise amplification in low-contrast regions.

Innovation Solution

Implementing a hardware-driven algorithm using user-configurable enhancement factors for brightness and contrast, stored in lookup tables, which reduces data movement and processor load, and employs spatial and temporal filtering to minimize tile boundaries and enhance contrast adaptively.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If histogram calculations are performed for each tile to enhance local contrast, then contrast enhancement quality is improved, but processor resources and power consumption increase significantly

Engineering Contradiction:

Improvecontrast enhancement qualityVSAvoidpower consumption

Core Design Contradiction:

Manufacturing precisionVSUse of energy by moving object

Solution Approach 1:

The image is divided into multiple tiles, and contrast enhancement is performed independently for each tile using histogram calculations. This segmentation allows localized contrast improvement while distributing the computational load across different regions, balancing quality enhancement with manageable processor resource usage.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Lookup tables containing enhancement factors are pre-calculated and stored based on historical histogram data. This preliminary action eliminates the need for real-time histogram calculations during display refresh, significantly reducing power consumption while maintaining contrast enhancement quality through adaptive lookup table selection.

Inventive Principle:

Principle #10Preliminary action

2Manufacturing precision

If histogram calculations are performed for each tile to enhance local contrast, then contrast enhancement quality is improved, but processor load and data movement increase

Engineering Contradiction:

Improvecontrast enhancement qualityVSAvoidprocessor efficiency

Core Design Contradiction:

Manufacturing precisionVSProductivity

Solution Approach 1:

Histogram data and enhancement factors are pre-calculated and stored in lookup tables during idle periods or previous frames. This preliminary computation eliminates the need for intensive real-time processor operations during critical display refresh cycles, improving processor efficiency while maintaining enhancement quality.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

Instead of performing full histogram calculations for each tile during display refresh, the system uses pre-computed lookup tables that contain copied enhancement factors. This copying approach drastically reduces data movement and processor load while preserving the contrast enhancement effects.

Inventive Principle:

Principle #26Copying

3Device complexity

If enhancement factors are applied uniformly to all tiles, then implementation simplicity is improved, but over-sharpening and noise amplification occur in low-contrast regions

Engineering Contradiction:

Improveimplementation simplicityVSAvoidover-sharpening and noise

Core Design Contradiction:

Device complexityVSObject-generated harmful factors

Solution Approach 1:

Different enhancement factors are applied to different tiles based on their specific contrast characteristics. The system calculates or retrieves tile-specific enhancement factors that adapt to local image content, preventing over-sharpening in already high-contrast regions while providing necessary enhancement in low-contrast areas. This local adaptation reduces harmful effects while maintaining implementation feasibility through the lookup table approach.

Inventive Principle:

Principle #3Local quality

4Productivity

If tile-based processing is used for local contrast enhancement, then processing efficiency is improved, but visible tile boundaries and non-smooth transitions occur

Engineering Contradiction:

Improveprocessing efficiencyVSAvoidvisual continuity

Core Design Contradiction:

ProductivityVSStability of the object's composition

Solution Approach 1:

Adjacent tiles share and combine their histogram data to calculate enhancement factors. This merging approach ensures that tiles at boundaries have compatible enhancement characteristics, creating smooth transitions and eliminating visible seams. The combined histogram information from neighboring tiles allows the enhancement to flow naturally across tile boundaries while maintaining the processing efficiency of the tile-based architecture.

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentUS20250217951A1Local adaptive contrast enhancement techniques

Publication Date: 2025.07.03 INTEL CORP

AI summary

In one embodiment, an apparatus includes hardware circuitry to determine a tile brightness value and a tile contrast value for each respective tile of a plurality of tiles that together comprise an input frame. The circuitry obtains a first enhancement factor (e.g., from a first lookup table) based on the tile brightness value and a second enhancement factor (e.g., from a second lookup table) based on the tile contrast value. The circuitry generates an output frame based on the first enhancement factor and the second enhancement factor.