Chroma Adjustment Unit for Multi-Chip Image Sensor Color Irregularities
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Solution Overview
Problem
Existing image processing devices using multi-chip image sensors suffer from color irregularities due to differences in chip characteristics, particularly in low-chroma areas, leading to noticeable color fluctuations and reduced chroma in low-chroma regions when using CIS and CCD image sensors for duplex document reading.
Innovation Solution
An image processing device with a chroma calculation unit and chroma adjustment unit that reduces chroma only in low-chroma image signals to suppress color irregularities, using a predetermined threshold value for chroma reduction, and selectively applies chroma conversion processing based on the reading method and sensor type.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If chroma conversion processing is performed on all image signals to suppress color irregularities, then color irregularities are suppressed, but chroma in low-chroma areas is unnecessarily reduced
Solution Approach 1:
The patent applies chroma conversion processing selectively based on local image characteristics. By calculating chroma values for each pixel and comparing against a threshold, the system performs chroma conversion only in regions where color irregularities are problematic, while preserving chroma in areas where it would be unnecessary. This local differentiation resolves the contradiction by making the processing adaptive to actual image content rather than applying uniformly.
Solution Approach 2:
The patent dynamically changes the chroma parameter based on image content analysis. By calculating chroma values and using threshold comparison, the system adjusts whether chroma conversion is applied on a pixel-by-pixel or region-by-region basis. This parameter-driven approach allows the system to maintain color accuracy where needed while preserving natural chroma where conversion would be harmful.
2Reliability
If chroma conversion processing is avoided in CCD reading operations to maintain chroma, then chroma is preserved, but color irregularities from multi-chip sensors remain noticeable
Solution Approach 1:
The patent implements different processing strategies for different sensor types and reading operations. For CCD-based reading operations, the system determines whether chroma conversion is necessary by analyzing actual color irregularities in the image, applying the principle of local quality assessment. This allows the system to preserve chroma in CCD images while still suppressing color irregularities where they occur, rather than applying a blanket approach.
Solution Approach 2:
The patent makes the chroma conversion processing dynamic and adaptive rather than static. The system calculates chroma values, compares them against thresholds, and dynamically decides whether to apply chroma conversion based on actual image content and sensor type. This dynamic approach allows the system to adapt to different reading operations (ADF vs. book reading) and sensor types (CCD vs. CIS), resolving the contradiction between chroma preservation and color uniformity.
3Measurement precision
If color correction is performed using traditional calibration techniques, then color accuracy is improved, but color irregularities in low-chroma areas persist due to chip characteristic differences
Solution Approach 1:
The patent goes beyond traditional calibration by dynamically calculating chroma values for each pixel or region and using threshold comparison to determine where chroma conversion is needed. This parameter-driven approach addresses color uniformity issues caused by chip characteristic differences by adaptively adjusting chroma based on actual image content, rather than relying solely on pre-calibrated correction coefficients.
Solution Approach 2:
The patent segments the image processing into different stages: initial color correction using calibration data, followed by chroma calculation and threshold-based chroma conversion. This segmentation allows the system to first establish accurate color reproduction and then separately address color uniformity issues in low-chroma areas, resolving the contradiction between color accuracy and color uniformity.
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 suppresses color irregularities in low-chroma areas while maintaining accurate color reproduction, ensuring consistent image quality across different reading methods and sensor types, particularly in duplex document reading operations.
Implementation Method 1
read an image of a document by converting light incident from the document into electrical signals
Data Source
AI summary
An image processing device, which can be incorporated in an image forming apparatus and perform an image processing method, includes a first image sensor unit including multiple image sensor chips arranged in a line to read an image of a document by converting light incident from the document into electrical signals, a chroma calculation unit to calculate chroma data from an image signal constituted by the electrical signals of the image read by the first image sensor unit, and a chroma adjustment unit to adjust the chroma by using the chroma data calculated by the chroma calculation unit to perform, only on a low-chroma image signal, a conversion process for reducing the chroma to suppress color irregularities occurring at intervals corresponding to widths of the multiple image sensor chips of the first image sensor unit.