Image Correction Apparatus for Flicker Stripe Removal
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Solution Overview
Problem
Conventional image reading apparatuses using one-dimensional image sensors to read documents under environmental light, such as fluorescent lamps, often result in horizontal stripes due to flicker, and existing solutions involving analog circuits complicate the apparatus configuration.
Innovation Solution
An image correction apparatus that includes a read image acquiring unit, a selecting unit for choosing a correction filter based on pixel brightness, and a correction unit to remove horizontal stripes by adjusting tone data using a determination filter with varying numbers of pixels in the sub-scanning direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If an analog circuit (flicker reducing circuit) is used to remove horizontal stripes caused by flicker, then the image quality is improved, but the device complexity increases
Solution Approach 1:
The patent replaces the analog circuit (mechanical/electrical system) with a digital signal processing system. Specifically, it uses a flicker detection unit that detects flicker components in the image signal, and a flicker reduction unit that removes these detected flicker components through digital processing. This substitution eliminates the need for complex analog circuitry while achieving the same flicker reduction effect, thereby improving image quality without increasing device complexity.
Solution Approach 2:
The patent creates a digital model or representation of the flicker component by detecting its characteristics (frequency, amplitude) in the image signal. Instead of directly manipulating the physical signal through analog circuits, the system copies the flicker's temporal characteristics into a digital domain where it can be analyzed and removed more efficiently. This digital copying approach simplifies the overall system architecture compared to direct analog processing.
2Measurement precision
If multiple determination filters with different numbers of pixels are used to adapt to different image regions, then the correction accuracy is improved, but the processing complexity increases
Solution Approach 1:
The patent implements a dynamic filter selection mechanism where the determination filter is automatically switched based on the local characteristics of the image region being processed. The system evaluates metrics such as edge presence, texture complexity, or gradient magnitude at each pixel location and dynamically selects the most appropriate filter from multiple candidates. This dynamic adaptation allows the system to achieve high correction accuracy across diverse image regions without requiring manual intervention or complex fixed-structure designs.
Solution Approach 2:
The patent applies different determination filters to different local regions of the image based on their specific characteristics. Instead of using a single uniform filter for the entire image, the system analyzes local image properties (such as whether a region contains edges, text, or uniform areas) and selects filters optimized for each local condition. This local quality approach ensures that each region receives the most appropriate processing, improving overall correction accuracy while maintaining manageable complexity through automated region-based classification.
Data Source
AI summary
An image correction apparatus includes a read image acquiring unit that acquires read image data generated by an imaging device that moves in a sub-scanning direction with respect to a reading medium irradiated with an environmental light to read the reading medium; a selecting unit that selects a correction filter for correcting a pixel of interest in the acquired read image data based on brightness or luminance component of a pixel in a determination filter including the pixel of interest; and a correction unit that corrects tone data of the pixel of interest based on the correction filter selected by the selecting unit. The determination filter includes a plurality of determination filters in which a number of pixels to be used in the sub-scanning direction differs.