Tone Gradation Correction Using Halftone Dot Area Measurement
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional image forming apparatuses face challenges in achieving satisfactory image quality on non-standard papers due to variations in paper density and surface properties, leading to issues like tone gradation defects, increased memory requirements, and user complexity in automatic tone gradation correction.
Innovation Solution
An image forming apparatus that includes an image reading station and a tone gradation corrector, which calculates halftone dot area properties and executes tone gradation correction based on these properties, allowing for effective tone gradation correction without the need for standard paper, thus accommodating various paper types and reducing memory costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If automatic tone gradation correction is performed on non-standard paper using conventional density measurement methods, then tone gradation correction can be executed, but the LUT varies due to paper surface properties, whiteness degree, and thickness, resulting in loss of tone gradation in shadow portions
Solution Approach 1:
The patent introduces a halftone dot area measurement as an intermediary parameter between the physical paper properties and the tone gradation correction. Instead of directly measuring density which varies with paper properties, the system measures the halftone dot area percentage which provides a stable, paper-independent metric for tone gradation correction, thereby resolving the contradiction between ease of operation and tone gradation quality
Solution Approach 2:
The patent changes the measurement parameter from density (which varies with paper properties) to halftone dot area percentage (which is independent of paper properties). This parameter transformation allows the same correction LUT to be applied across different paper types, maintaining tone gradation quality while enabling automatic correction on non-standard paper
2Manufacturing precision
If multiple LUTs are prepared for different paper types to maintain tone gradation quality, then tone gradation can be preserved, but memory requirements increase and device complexity increases
Solution Approach 1:
The patent creates a universal correction approach by using halftone dot area percentage as a paper-independent measurement metric. This allows a single LUT to serve multiple paper types, eliminating the need for separate LUTs for different papers, thereby reducing memory requirements while maintaining tone gradation quality across various recording materials
Solution Approach 2:
By transforming the measurement parameter to halftone dot area percentage, the system achieves parameter universality that works across different paper types. This single parameter change enables one LUT to replace multiple paper-specific LUTs, reducing device complexity and memory usage while preserving tone gradation quality
3Measurement precision
If LUT is prepared based on non-standard paper B with lower maximum density, then density measurement can be performed, but tone gradation is lost in shadow portions above 240th level
Solution Approach 1:
The patent uses halftone dot area percentage as an intermediary measurement that decouples the measurement from paper density variations. This intermediary metric allows accurate measurement across all tone levels including shadow portions, regardless of paper density characteristics, thereby preventing tone gradation loss while maintaining measurement precision
Solution Approach 2:
Instead of adjusting the LUT to match the limited dynamic range of low-density paper (which causes tone gradation loss), the patent inverts the approach by using a paper-independent measurement metric that captures the full tone range. This inversion allows the LUT to be optimized for full tone gradation while the measurement system adapts to different paper densities
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
The solution enables high usability and memory-efficient engine tone gradation correction, providing smooth tone gradation and improved image quality across different paper types without the need for standard paper, thereby addressing the limitations of conventional methods.
Implementation Method 1
an image reading station for reading a pattern image formed on a recording material by said image forming station
Data Source
AI summary
An image forming apparatus includes an image forming station for forming a pattern image on a recording material; an image reading station for reading a pattern image formed on a recording material by the image forming station; and a tone gradation corrector for calculating a halftone dot area property on the basis of the density of the pattern image read by the image reading station and for executing tone gradation correction in the image forming station on the basis of the calculated halftone dot area property.