Halftone Image Interpolation Using Analogous Pattern Synthesis
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Solution Overview
Problem
Existing image forming apparatuses face challenges in accurately interpolating pixel values for halftone images due to limitations in resolution and pattern matching, leading to interpolation errors and degradation of image quality, especially when dealing with drastically changed pixel values.
Innovation Solution
An image forming apparatus and method that computes accurate pixel values for halftone images by setting a base pattern, acquiring analogous patterns from a peripheral region, creating a high-resolution pattern by synthesizing these patterns, and determining the correct pixel value based on the high-resolution pattern, effectively addressing the limitations of existing interpolation methods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If general polynomial interpolation is used for halftone images, then the interpolation process is simple, but the interpolation accuracy is significantly degraded due to the sampling cycle being insufficiently short relative to the fluctuation cycle of the halftone pattern
Solution Approach 1:
The patent segments the halftone image into multiple regions based on screen angles and lines per inch characteristics. By dividing the image into distinct halftone regions, the system can apply appropriate interpolation methods to each region, improving overall interpolation accuracy while managing complexity through localized processing rather than global polynomial interpolation
Solution Approach 2:
The patent changes the interpolation parameters dynamically based on the detected halftone characteristics (screen angle, lines per inch). Instead of using fixed polynomial interpolation parameters, the system adjusts the search range, pattern matching criteria, and regional boundaries according to the specific halftone parameters, thereby achieving accurate interpolation for drastically changed pixel values
2Adaptability or versatility
If the search range of analogous pattern is increased to find appropriate patterns for interpolation, then more patterns are available for matching, but the interpolation is easily affected by changes in content-dependent colors or luminance of the image
Solution Approach 1:
The patent applies local quality by setting different search ranges and pattern matching criteria for different regions of the image based on their halftone characteristics. For regions with specific screen angles and lines per inch, the system adjusts the local search parameters to optimize pattern matching, thereby finding appropriate analogous patterns without being overly influenced by distant regions with different content-dependent colors or luminance
Solution Approach 2:
The patent performs preliminary detection of halftone parameters (screen angle, lines per inch) and pre-segments the image into regions before conducting pattern matching. This preliminary action allows the system to establish region-specific search ranges and criteria in advance, ensuring that pattern matching is performed with appropriate local parameters rather than a uniform wide search range that would introduce color and luminance variations
Data Source
AI summary
An image forming apparatus includes an image interpolation unit to compute a correct pixel value of a target pixel subject to interpolation of a halftone image. The image interpolation unit includes a base pattern setting unit to set a base pattern including the target pixel, a reference pattern setting unit to set reference pattern in a region peripheral to the target pixel, an analogous pattern acquisition unit to acquire at least one analogous pattern analogous to the base pattern from the reference pattern, a high-resolution pattern creating unit to create a high-resolution pattern having a predetermined resolution or higher by synthesizing the acquired analogous pattern, a pixel value estimating unit to compute an estimated pixel value of the target pixel based on the created high-resolution pattern, and a pixel value determination unit to determine the correct pixel value of the target pixel based on the computed estimated pixel value.