Dither Threshold Matrix for Thin Line Density Control
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Solution Overview
Problem
Existing image processing techniques using dither methods often result in breaks on thin lines due to inconsistent dot placement, especially when printing conditions change, leading to deviations from the intended intermediate density.
Innovation Solution
An image processing apparatus and method that adjusts threshold values in a threshold matrix based on signal values to determine whether to print dots, using multiple threshold values to ensure consistent dot placement and desired density without breaks, regardless of printing conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a dither method with a fixed threshold matrix is used for quantization, then the processing is simple and fast, but breaks occur on thin lines and density reproduction is poor
Solution Approach 1:
The patent applies dynamics by making the threshold matrix adaptable to different printing conditions. Instead of using a fixed threshold matrix, the system dynamically adjusts the threshold values based on the actual printing mode and conditions, allowing the quantization process to maintain both speed and precision across various scenarios.
Solution Approach 2:
The patent changes the parameters of the threshold matrix based on printing conditions. By modifying the threshold values according to the specific printing mode (e.g., different paper types, ink conditions), the system optimizes density reproduction while maintaining processing efficiency.
2Reliability
If threshold values are adjusted to add dots in thin line areas, then breaks on thin lines are suppressed, but the intermediate density may deviate significantly from the designated density
Solution Approach 1:
The patent applies local quality by making different adjustments to different regions of the image. Specifically, threshold values are selectively modified only in thin line areas where breaks are likely to occur, while leaving other areas unchanged. This localized approach suppresses breaks without causing significant deviation in overall intermediate density.
Solution Approach 2:
The patent changes threshold parameters selectively based on local image characteristics. By identifying thin line regions and adjusting threshold values only in those specific areas, the system maintains thin line continuity while preserving the overall density accuracy of the image.
3Device complexity
If a uniform method is used to add dots regardless of printing conditions, then the process is simple, but the dot number may be too large or too small for different printing modes
Solution Approach 1:
The patent makes the dot addition process dynamic by adapting to different printing conditions. The system automatically adjusts the number and position of added dots based on the specific printing mode, ensuring appropriate results for various scenarios without requiring complex manual intervention.
Solution Approach 2:
The patent changes the parameters controlling dot addition based on printing conditions. By modifying threshold values and dot placement parameters according to the specific printing mode, the system achieves versatility across different conditions while maintaining relatively simple processing logic.
Data Source
AI summary
The present invention provides an image processing apparatus which employs a dither method capable of printing a thin line of desired density without any break irrespective of printing conditions. The first threshold changing unit changes part of threshold values in a threshold matrix to generate a first threshold matrix so as to increase the number of dots to be printed in a specific pixel area. The second threshold changing unit changes part of threshold values in the threshold matrix to generate a second threshold matrix such that the number of dots to be printed in a specific pixel area is smaller than the case of changing a threshold value by the first threshold changing unit. A determining unit determines whether a threshold value in the threshold matrix is to be changed by the first threshold changing unit or by the second threshold changing unit.