Hardware Background Removal Using RGB to YCrCb Conversion

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Solution Overview

Problem

Existing image processing systems in multifunction devices struggle to efficiently remove background noise and colors in RGB color space, requiring significant hardware logic and lacking efficient methods to quantify pixel colorfulness for effective background removal.

Innovation Solution

The system converts RGB pixels to YCrCb color space using bit-shift operations, evaluates pixel characteristics by comparing color space components to threshold values, and implements background removal using minimal hardware logic, reducing the number of logic gates and enhancing processing speed.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If traditional background removal methods are implemented in hardware, then processing speed is improved, but hardware logic complexity increases

Engineering Contradiction:
Improveprocessing speedVSAvoidhardware logic complexity
Core Design Contradiction:
SpeedVSDevice complexity

Solution Approach 1:

The patent extracts only the essential background removal functionality from complex software algorithms and implements it in hardware. By taking out the core histogram-based background identification and pixel value thresholding operations, the system achieves hardware-speed processing while minimizing unnecessary logic complexity.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent uses simple, resource-efficient hardware components that can be easily manufactured and replaced. The background removal logic is implemented using basic logic gates and lookup tables rather than complex programmable structures, creating a simple, fast, and cost-effective hardware solution.

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

2Ease of manufacture

If background removal logic is minimized in ASIC design, then manufacturing cost is reduced, but processing capability may be limited

Engineering Contradiction:
Improvemanufacturing costVSAvoidprocessing capability
Core Design Contradiction:
Ease of manufactureVSProductivity

Solution Approach 1:

The patent changes the operational parameters of the background removal algorithm to suit hardware implementation. Instead of using complex multi-dimensional histograms, the system uses simplified 1D histograms based on luminance values and straightforward thresholding, maintaining effectiveness while reducing logic requirements.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The background removal process is segmented into distinct hardware stages: luminance calculation, histogram construction, threshold determination, and pixel classification. This segmentation allows each stage to be implemented with simple, dedicated logic, reducing overall complexity while maintaining processing capability.

Inventive Principle:
Principle #1Segmentation

3Measurement precision

If color space conversion is implemented accurately, then color accuracy is improved, but hardware resource usage increases

Engineering Contradiction:
Improvecolor accuracyVSAvoidhardware resource usage
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent uses simplified, approximate color space conversion formulas that can be implemented with basic arithmetic operations. Rather than using full-precision matrix multiplication, the system employs scaled integer arithmetic and bit-shifting operations that maintain sufficient accuracy for background removal while using minimal hardware resources.

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

Solution Approach 2:

The patent applies color space conversion only where necessary for background removal decisions, rather than converting entire images with full precision. The conversion is performed locally on a per-pixel basis using simplified formulas, providing sufficient color information for background identification without the overhead of complete color accuracy.

Inventive Principle:
Principle #3Local quality

Data Source

PatentUS7433085B2Intelligent hardware for detecting color value of an image
Publication Date: 2008.10.07 LEXMARK INTERNATIONAL INC
  • US7433085B2 patent drawing
  • US7433085B2 patent drawing
  • US7433085B2 patent drawing

AI summary

Pixel characteristics, such as whether a pixel forms part of the background of an image, are evaluated by computing histograms from pixel color space components, by comparing pixel color space components to threshold values, or by other methods.