Image Processing Quantization Frequency Adjustment for Beat Suppression
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Solution Overview
Problem
Ink jet recording apparatuses face issues with streaky unevenness due to nozzle discharge abnormalities, leading to recognizable beats and inadequate correction of defects, especially in complex nozzle layouts, where existing techniques fail to effectively suppress beats and maintain image quality.
Innovation Solution
An image processing method that detects abnormalities in recording elements, modulates pixel densities to invisibilize defects, and adjusts the peak frequency component of quantization to exclude the frequency band around the spatial frequency peak of the correction region, allowing for effective suppression of beats across various nozzle layouts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If density modulation is performed for each nozzle group to correct streaky unevenness, then uniformity of density across nozzle groups is improved, but recognizable beats are generated due to interference between frequency characteristics of nozzle groups and quantization
Solution Approach 1:
The patent changes the frequency characteristics of quantization by adjusting the quantization matrix or algorithm to avoid overlap with the frequency characteristics of nozzle groups. This parameter adjustment eliminates the interference that causes beats while maintaining density uniformity across nozzle groups.
Solution Approach 2:
The patent introduces asymmetric frequency distribution by deliberately designing the quantization frequency characteristics to be asymmetric relative to the nozzle group frequency characteristics. This asymmetry prevents coherent interference and eliminates beats while preserving the density correction effect.
2Object-generated harmful factors
If conventional beat suppression techniques are applied, then beats are suppressed in simple nozzle layouts, but effectiveness deteriorates in complex nozzle layouts where correspondence between nozzles and pixels is not one-to-one
Solution Approach 1:
The patent develops a universal quantization frequency adjustment technique that works across all nozzle layouts regardless of complexity. The method adapts to different correspondence relationships between nozzles and pixels by dynamically analyzing the actual frequency characteristics and adjusting quantization parameters accordingly, making it applicable to both simple and complex layouts.
Solution Approach 2:
The patent introduces dynamic adjustment of quantization frequency characteristics based on the specific nozzle layout configuration. The system automatically adapts to different nozzle arrangements and pixel correspondence relationships, changing the quantization parameters in real-time to maintain effectiveness across various layout complexities.
Data Source
AI summary
Provided are an image processing method, an image processing device, and an image recording apparatus capable of suppressing generation of beats, even in a case where streaky unevenness correction other than non-discharge correction of a recording element is performed, in any nozzle layout shapes. An image processing method comprises an abnormality detection step of detecting an abnormality for each recording element in a recording head in which a plurality of the recording elements are arranged; an invisibilization step of modulating densities of pixels to be recorded on a recording medium by the correction recording element including an abnormal recording element of which the abnormality has been detected to invisibilize a defect of an image, in order to correct the defect of the image resulting from the abnormal recording element depending on a detection result in the abnormality detection step; and a quantization step of quantizing an image to be recorded on the recording medium, and performing the quantization such that a peak frequency component of the quantization is located in a frequency band excluding a frequency band around a spatial frequency peak of a correction region that is a pixel group to be recorded on the recording medium by the correction recording element of which a density has been modulated by the invisibilization step.