Glare Reduction in Graphical Code Readers
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Solution Overview
Problem
Graphical code readers face challenges in reducing glare, which affects the accuracy of image capture and decoding due to uneven and non-uniform illumination, particularly when reading codes on reflective surfaces.
Innovation Solution
A graphical code reader system that includes an optic system, image sensor, and control system to detect glare and adjust illumination settings based on contrast and saturation, using multiple light sources such as IR and red illumination, and sequencing light sources to minimize glare through rolling shutter techniques and glare correction regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If multiple light sources are used to illuminate the field of view, then illumination coverage is improved, but glare is increased due to reflections from reflective surfaces
Solution Approach 1:
The patent applies periodic action by sequentially activating different light sources (IR and red LEDs) in alternating frames rather than simultaneously. The control system determines which light source to activate based on detected glare conditions, creating a time-based illumination pattern that reduces cumulative glare while maintaining adequate illumination coverage across the field of view.
2Illumination intensity
If gain is adjusted to improve image brightness, then image quality is improved, but saturation increases in high-contrast regions
Solution Approach 1:
The patent applies local quality by implementing region-specific gain adjustment where different gain values are applied to different portions of the image based on their contrast characteristics. The control system identifies high-contrast regions (such as barcode areas) and applies selective gain modulation to maintain brightness in low-contrast areas while preventing saturation in high-contrast regions, thereby achieving localized optimization of image quality.
3Object-affected harmful factors
If intensity of illumination is reduced to minimize glare, then glare is reduced, but image brightness decreases
Solution Approach 1:
The patent applies dynamics by implementing real-time, adaptive control of illumination intensity based on detected glare conditions and image characteristics. The control system dynamically adjusts the intensity of each light source frame-by-frame, increasing intensity when glare is absent to maintain brightness, and reducing intensity when glare is detected, thereby achieving dynamic optimization of the trade-off between glare reduction and image brightness maintenance.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system effectively reduces glare, improving image quality and decoding accuracy by adjusting illumination settings and sequencing light sources, ensuring even illumination and enhancing the readability of graphical codes on various surfaces.
Implementation Method 1
determine that glare is present in an image captured by the optic system by identifying reflection from at least one of the plurality of light sources
Implementation Method 2
a plurality of light sources configured to illuminate the field of view of the image sensor
Data Source
AI summary
A method for glare reduction may be implemented by a graphical code reader. The graphical code reader includes an optic system, a plurality of light sources, and a control system. The control system is configured to determine that glare is present in an image captured by the optic system by identifying reflection from at least one of the plurality of light sources. The control system may take a corrective action to reduce the glare in subsequent images. The control system may be configured to take a first corrective action if a diffraction pattern is present at a periphery of the glare, and take a second corrective action if a diffraction pattern is not present at the periphery of the glare.