Flatbed Scanner Shading Correction for External Light
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Solution Overview
Problem
Flatbed image scanning apparatuses face challenges in accurately scanning thick originals due to interference from external light, which degrades image quality reproducibility, as existing shading correction methods are ineffective when using inappropriate predetermined parameters.
Innovation Solution
An image scanning apparatus with a controller unit that includes an external light detection system and light control unit, which adjusts the light source LEDs' emission based on shading data acquisition and light control processing to minimize external light influence, using range-restricted light control and shading data rewriting to correct for external light interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If shading correction is performed using predetermined parameters when external light is detected, then the influence of external light is reduced, but appropriate shading correction cannot be performed when the predetermined parameters are not suitable for the current environment
Solution Approach 1:
The system performs preliminary shading data acquisition in advance and stores multiple sets of shading data corresponding to different external light conditions. When external light is detected during scanning, the system selects and applies the pre-acquired shading data that matches the current external light conditions, rather than using fixed predetermined parameters or attempting real-time correction.
Solution Approach 2:
The system changes the parameters used for shading correction based on the detected external light conditions. By detecting the presence and characteristics of external light, the system selects appropriate shading data sets with different correction parameters, thereby adapting the shading correction to match the current scanning environment and maintaining accuracy across varying conditions.
2Device complexity
If conventional shading correction is performed without considering external light, then the scanning process is simple, but image quality reproducibility deteriorates when scanning thick originals
Solution Approach 1:
The system performs preliminary detection of external light conditions and preliminary acquisition of appropriate shading data before the actual scanning process. This advance preparation allows the system to have correction data ready that is specifically suited for the detected external light conditions, ensuring accurate shading correction without adding complexity to the main scanning operation.
Solution Approach 2:
The system incorporates a feedback mechanism where external light detection results from the scanning process inform the selection of appropriate shading data. The detection unit continuously monitors for external light, and based on this feedback, the system selects the corresponding pre-acquired shading data to apply, creating a closed-loop system that maintains image quality reproducibility.
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
Effectively reduces the impact of external light on scanning, ensuring accurate image reproduction even for thick originals by dynamically adjusting light sources and correcting shading data, thereby enhancing image quality and productivity.
Implementation Method 1
light source LEDs 113
Implementation Method 2
image sensor formed by arranging elements each for photoelectrically converting light into an electrical signal
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
An image scanning apparatus (101) determines whether there is an influence of external light from the outside on scanning; decides a correction value corresponding to each of a plurality of sensors (112) based on received light amounts of at least some of the plurality of sensors; and corrects, using the correction value corresponding to each of the plurality of sensors and decided, data corresponding to a received light amount of each of the plurality of sensors when scanning the original, wherein if it is determined that there is the influence of the external light, the image scanning apparatus decides the correction value corresponding to a first sensor and the correction value corresponding to a second sensor arranged at a position that is readily influenced by the external light based on the received light amount of the first sensor.