Digital Moire Correction via Optical Transfer Functions
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Solution Overview
Problem
Existing image processing methods are limited in effectively correcting moire components in images, particularly due to complex apparatus configurations and limitations in correcting color noise, and are often specific to printing applications, failing to address moire issues in general image pickup systems.
Innovation Solution
An image processing apparatus that includes an estimator to calculate moire components based on optical characteristics, a determiner to determine correction amounts, and a corrector to reduce moire components in images, utilizing optical transfer functions and singular value decomposition to improve linearity and reduce moire effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If an optical low-pass filter is inserted to attenuate frequency response near Nyquist frequency, then moire generation is reduced, but image resolution is deteriorated
Solution Approach 1:
The patent replaces the mechanical/optical low-pass filter with a digital signal processing approach. The image processing apparatus applies frequency domain filtering algorithms to attenuate moire components digitally after image capture, eliminating the need for physical optical filters that would compromise image resolution.
Solution Approach 2:
The patent introduces frequency characteristic information as an intermediary element. This information about the imaging system's frequency response is used to guide the digital filtering process, allowing selective attenuation of moire frequencies while preserving useful image frequencies, thus avoiding the blanket resolution loss caused by optical low-pass filters.
2Object-affected harmful factors
If multiple images are captured while driving the image pickup optical system minutely, then moire correction is achieved, but device complexity increases
Solution Approach 1:
The patent extracts the moire correction function from the optical system and relocates it to the digital image processing domain. By analyzing frequency characteristics of the captured image and applying corrective filtering algorithms, the system eliminates moire without requiring complex optical drive mechanisms or multiple capture operations.
Solution Approach 2:
The patent uses frequency characteristic information as a digital model or copy of the imaging system's behavior. This model guides the correction process, allowing the system to predict and remove moire artifacts based on theoretical frequency responses rather than requiring physical system variations or multiple captures.
3Manufacturing precision
If conventional image processing methods are used for moire correction in printing applications, then printing quality is improved, but general image pickup systems cannot benefit
Solution Approach 1:
The patent creates a universal image processing apparatus that can handle moire correction across different application domains. The frequency domain filtering method is formulated in a way that works for both printing preparation and general image pickup systems, making the solution broadly applicable rather than domain-specific.
Solution Approach 2:
The patent adjusts processing parameters based on the specific application context. By modifying filtering strength, frequency thresholds, and correction amounts according to whether the output is for printing or general display, the same core algorithm serves multiple purposes effectively.
Data Source
AI summary
An image processing apparatus includes an estimator (804b) which estimates a moire component included in an image based on optical characteristic information, a determiner (804c) which determines a correction amount based on the estimated moire component, and a corrector (804d) which corrects the image so as to reduce the moire component included in the image based on the correction amount.