Image Reading Apparatus Dust Detection Noise Suppression

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Solution Overview

Problem

Conventional image reading apparatuses face inefficiencies in dust detection due to long startup times, reduced reading efficiency, and decreased accuracy caused by random noise components in image data, leading to erroneous detection of dust and scratches.

Innovation Solution

The implementation of a random noise suppressing device that averages or interpolates image data, combined with a shading correction device, to enhance the accuracy of dust detection by suppressing random noise components in the image data before anomaly detection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional dust detection is performed using raw image data, then detection speed is maintained, but detection accuracy deteriorates due to random noise components causing erroneous false positives

Engineering Contradiction:
Improvedust detection accuracyVSAvoidfalse positive rate
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The patent applies preliminary action by performing noise suppression processing on image data before dust detection. The random noise suppressing device processes the image data in advance to remove noise components, ensuring that subsequent dust detection operates on cleaned data, thereby preventing false positives while maintaining detection speed

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent introduces an intermediary element - the random noise suppressing device - that acts as a mediator between image data acquisition and dust detection. This intermediary processes the raw image data to eliminate noise components before the detection phase, improving both accuracy and reliability without creating a direct trade-off

Inventive Principle:
Principle #24Intermediary (Mediator)

2Measurement precision

If noise suppression processing is applied to image data before dust detection, then detection accuracy improves, but processing time increases

Engineering Contradiction:
Improvedust detection accuracyVSAvoiddust determination time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent applies parameter changes by optimizing the noise suppression algorithm to operate with specific parameters that balance processing speed and effectiveness. By adjusting parameters such as the degree of smoothing or the threshold for noise removal, the system achieves adequate noise suppression without excessive processing time, maintaining real-time detection capability

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent implements skipping by using efficient noise suppression techniques that quickly process image data without thorough multi-stage filtering. The system rushes through the noise suppression process using optimized algorithms that provide sufficient noise reduction in a single pass, preventing time loss while improving detection accuracy

Inventive Principle:
Principle #21Skipping (Rushing through)

3Measurement precision

If standard white plate is used for shading correction, then correction accuracy is maintained, but the plate itself becomes susceptible to dust contamination affecting future readings

Engineering Contradiction:
Improveshading correction accuracyVSAvoiddust contamination on reference plate
Core Design Contradiction:
Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent applies preliminary action by implementing dust detection on the standard white plate before it is used for shading correction. By detecting and accounting for dust particles in advance, the system can compensate for their presence during correction operations, maintaining accuracy while preventing dust from degrading future measurement quality

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent implements feedback by using dust detection results to adjust the shading correction process. The system detects dust on the reference plate, feeds this information back into the correction algorithm, and modifies the correction accordingly, thereby maintaining correction accuracy despite the presence of contamination on the reference plate

Inventive Principle:
Principle #23Feedback

Data Source

PatentUS7518757B2Image reading apparatus and control program therefor
Publication Date: 2009.04.14 CANON KK
  • US7518757B2 patent drawing
  • US7518757B2 patent drawing
  • US7518757B2 patent drawing

AI summary

There is provided an image reading apparatus that is capable increasing the detection accuracy for dust, scratches, dirt, and the like. Sixty-four lines of sampling points on a reference standard white plate are read, shading correction and averaging are carried out the read image data to suppress random noise components in the image data, the data is then stored in a sampling memory, and dust detection is carried out on the data stored in the sampling memory. Alternatively, shading correction and dust detection are carried out on image data that has been subjected to linear interpolation. It is thus possible to increase the accuracy of detection of dust, scratches, dirt, and the like while ensuring that shading correction is performed at high speed.