Image Processing Apparatus End Edge Masking for ACS Accuracy
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Solution Overview
Problem
Conventional image forming apparatuses face errors in automatic color selection (ACS) when handling irregular-sized originals or mixed sizes, leading to erroneous chromatic or achromatic determinations, especially when originals are lifted during passage through an automatic document feeder (ADF), due to undefined end edges and increased costs associated with application-specific integrated circuits (ASICs) requiring more input pins.
Innovation Solution
An image processing apparatus that conveys originals line by line, scans to generate image information, detects whether each line is chromatic or achromatic, and determines the original's nature based on a first area excluding a predetermined second area, which includes the end line in the scanning direction, using a delay circuit to mask determination results from the end edge area, thereby preventing erroneous detections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the end edge area of the original is included in the detection area for ACS determination, then the detection coverage is improved, but erroneous detection occurs when the end edge is lifted during ADF passage
Solution Approach 1:
The patent segments the original image into multiple line regions in the sub-scan direction. It identifies an end edge region (lines containing original end edges) and a non-end edge region (other lines). The ACS determination is performed separately for these regions, allowing the system to exclude unreliable end edge detections while maintaining accurate detections from stable regions.
Solution Approach 2:
The patent applies different quality standards to different regions of the original. End edge regions are treated differently from non-end edge regions due to their inherent instability during ADF passage. The system recognizes that end edge areas have lower detection reliability and adjusts the ACS determination process accordingly by giving more weight to or prioritizing results from non-end edge regions.
2Reliability
If a determination inhibiting signal is generated based on timing from conveying roller to reading position, then erroneous detection is prevented, but variations in assembly cause timing inaccuracies
Solution Approach 1:
Instead of relying on precise timing measurements that are sensitive to assembly variations, the patent uses a spatial copy approach. It identifies lines containing original end edges and creates a determination inhibiting signal based on the spatial position of these lines. This spatial-based approach replaces the time-based timing method, eliminating sensitivity to mechanical assembly variations while maintaining the ability to prevent erroneous detections.
3Measurement precision
If ASIC with more input pins is used for precise timing detection, then detection accuracy is improved, but manufacturing cost increases
Solution Approach 1:
The patent replaces the mechanical timing-based system with a spatial/image-processing-based system. Instead of using complex ASIC circuits with multiple input pins for precise timing detection, the system uses image line data and spatial position information to generate determination inhibiting signals. This substitution eliminates the need for expensive hardware while achieving the same goal of preventing erroneous ACS detections.
Data Source
AI summary
An image processing apparatus includes a detecting unit that detects whether image data for each of the lines in generated image information is chromatic or achromatic; and a determining unit that determines whether the original is chromatic or achromatic based on a detection result of the detecting unit for a first area of the image information, excluding a detection result for a predetermined second area of the image information, the predetermined second area including an end line among the lines in a scanning direction of the original.