Image Reading Apparatus Dirt Detection via Document Edge Shadows
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Solution Overview
Problem
Existing image reading apparatuses face challenges in accurately detecting dirt substances, such as paper dust or glue, on the imaging device's glass surface, leading to noise lines in captured images, which affect image quality.
Innovation Solution
The apparatus includes a transparent member, a white reference member, an imaging device, and a light source positioned to form shadows of the document's leading or trailing edges on the white reference member, allowing a processor to detect dirt substances within the shadow regions of the input image.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional imaging device is used to capture document images, then the document content can be read, but dirt substances on the glass surface cannot be accurately detected
Solution Approach 1:
The imaging system is segmented into two functional parts: a first imaging device for capturing document images and a second imaging device for detecting dirt substances on the glass surface. This segmentation allows each device to be optimized for its specific function, improving dirt detection accuracy without compromising document imaging capabilities.
Solution Approach 2:
A light source is introduced as an intermediary element positioned to illuminate the glass surface at a specific angle, creating shadows of dirt substances that are visible to the second imaging device. This intermediary lighting setup enables the detection of dirt substances that would otherwise be difficult to distinguish from the background.
2Reliability
If the light source is positioned to form shadows of document edges on the white reference member, then dirt substances can be detected in shadow regions, but the device complexity increases
Solution Approach 1:
The light source is positioned in advance to create shadow regions on the white reference member where dirt substances are likely to be detected. This preliminary arrangement of lighting ensures that when the document is conveyed, any dirt on the glass surface will cast shadows in predetermined detection zones, making detection more reliable without requiring complex real-time adjustments.
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
This configuration enables improved detection of dirt substances, effectively reducing noise lines and enhancing image quality by accurately identifying both black and white dirt substances, even when they resemble the background color.
Implementation Method 1
The light source is provided such that a shadow of a leading end or rear end of the document conveyed on the transparent member is formed on the white reference member at the imaging position
Implementation Method 2
an imaging device for, provided on an opposite side of the white reference member across the transparent member, generating an input image of a document and a periphery of the document
Data Source
AI summary
An image processing apparatus includes a transparent member, a white reference member, an imaging device, a conveyance member, a light source, and a processor for detecting a dirt substance from the input image. The light source is provided such that a shadow of a leading end or rear end of the document conveyed on the transparent member is formed on the white reference member at the imaging position. The processor detects a shadow region formed by the leading end or rear end of the conveyed document from the input image and detects a dirt substance from within the detected shadow region.