Adaptive Pixel Interpolation for Halftone and Smooth Areas
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Solution Overview
Problem
Conventional pixel interpolation methods fail to achieve high precision, especially in images with significant pixel value variations, and incorrectly determine areas between halftone and background regions, leading to inaccurate pixel value estimation.
Innovation Solution
An image processing device that determines whether a pixel belongs to a periodic or non-periodic area using a periodicity determining unit and a boundary determining unit, then selects between two different interpolation methods based on these determinations to generate accurate pixel values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If linear interpolation method is used, then interpolation is suitable for portions with small density variation, but it is not suitable for portions with large density variation such as halftone dot areas
Solution Approach 1:
The patent applies local quality by making the interpolation method adaptive to local image characteristics. The system determines whether each interpolation target pixel is located in a halftone dot area or non-halftone dot area, and then selects different interpolation methods accordingly. This allows the system to use linear interpolation for smooth areas with small density variations while using pattern matching for halftone dot areas with large density variations, thereby achieving high precision interpolation across different types of regions.
2Measurement precision
If polynomial interpolation or spline interpolation is used, then pixel values can be estimated with high precision for digital photographs, but original pattern is not correctly reconstructed for halftone dot images
Solution Approach 1:
The patent implements local quality by making the interpolation approach dependent on the local image characteristics. The system determines whether the interpolation target pixel is in a halftone dot area or non-halftone dot area, and selects different interpolation methods accordingly. For non-halftone dot areas, polynomial or spline interpolation provides high precision pixel value estimation. For halftone dot areas, pattern matching correctly reconstructs the original pattern by finding similar patterns in the vicinity, thus resolving the contradiction between precision and reliability.
3Measurement precision
If pattern matching is used, then high frequency component can be reconstructed, but the optimum solution is not always optimum for the interpolation pixels
Solution Approach 1:
The patent applies local quality by making pattern matching selective rather than universal. The system determines whether the interpolation target pixel is in a halftone dot area or non-halftone dot area, and only applies pattern matching to halftone dot areas where it can effectively reconstruct high frequency components. For non-halftone dot areas, the system uses other interpolation methods that provide more accurate results, thus avoiding the problem of pattern matching not always providing the optimum solution.
4Device complexity
If a single interpolation method is used for all areas, then the device complexity is reduced, but the interpolation precision for different types of areas cannot be optimized
Solution Approach 1:
The patent implements local quality by making the interpolation system adaptive to local image characteristics. The system includes a determination unit that identifies whether each interpolation target pixel is in a halftone dot area or non-halftone dot area, and then selects different interpolation methods accordingly. This approach increases interpolation precision for different types of areas while keeping the increase in device complexity manageable through automated determination and selective application of different methods.
Data Source
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AI summary
An image processing device that generates a pixel value of a pixel and interpolates the pixel with the pixel value, the image processing device including: a periodicity determining unit that determines whether an area including the pixel is a periodic area; a boundary determining unit that determines whether the pixel belongs to the periodic area or a non-periodic area; a first pixel value generating unit that generates a first pixel value; a second pixel value generating unit that generates a second pixel value; a control unit that determines whether the first pixel value generating unit is to be used or the second pixel value generating unit is to be used, based on determination results of the periodicity determining unit and the boundary determining unit; a pixel value inputting unit that inputs one of the first pixel value and the second pixel value to the pixel.