Color Image Forming Apparatus Misregistration Correction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing color image forming apparatuses face challenges with misregistration due to unevenness or misalignment of the deflection scanning apparatus, leading to density unevenness in fine images, particularly when electrical correction methods are applied without considering image color, resulting in impractical storage requirements and potential worsening of density issues.
Innovation Solution
A method for a color image forming apparatus that includes a first conversion part for pixel-level misregistration correction and a second conversion part for fractional pixel correction, along with a judgment part that determines whether to apply fractional pixel correction based on surrounding pixels, considering image color to improve output quality without significant cost increases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If electrical correction of misregistration is applied without considering image color, then misregistration can be corrected, but density unevenness occurs in fine images and memory storage requirements become impractical
Solution Approach 1:
The patent applies different correction strategies based on local image characteristics - specifically distinguishing between fine images and non-fine images, and between different color components. For fine images, pixel-level correction is avoided to prevent density unevenness, while for non-fine images, full pixel-level correction is applied. This local differentiation resolves the contradiction by adapting the correction method to the specific characteristics of each image region and color channel.
Solution Approach 2:
The patent changes the correction parameter (correction amount) based on the color component and image type. By adjusting the correction amount differently for each color component (C, M, Y, K) and for fine versus non-fine images, the system achieves effective misregistration correction while avoiding density unevenness in fine images. This parameter adaptation resolves the contradiction between correction effectiveness and density uniformity.
2Manufacturing precision
If pixel-level misregistration correction is applied to all images, then misregistration is corrected, but density unevenness occurs in fine images
Solution Approach 1:
The patent implements local quality control by identifying fine images and applying different correction treatments. For fine images, pixel-level correction is suppressed to maintain density uniformity, while for non-fine images, full pixel-level correction is applied to ensure misregistration correction. This selective approach maintains image quality across different image types while still achieving misregistration correction where appropriate.
Solution Approach 2:
The patent applies partial correction rather than full correction in all cases. By applying pixel-level correction only to non-fine images and using alternative correction methods for fine images, the system achieves sufficient misregistration correction without the excessive action that would cause density unevenness. This partial action approach maintains both misregistration correction and image quality.
3Manufacturing precision
If fractional pixel correction is applied to fine images, then misregistration correction is improved, but density unevenness worsens
Solution Approach 1:
The patent applies local quality control by specifically targeting fine images and preventing fractional pixel correction from being applied to them. By identifying fine images through analysis of pixel density distribution and correction amount characteristics, the system avoids the harmful effect of fractional pixel correction on these images while still applying such correction to non-fine images where it provides benefit without causing density unevenness.
Data Source
AI summary
A color image forming apparatus includes a coordinate conversion part, which converts a ordinate value, for executing a misregistration correction in the unit of a pixel; a gradation conversion part, which converts a gradation level, for executing a misregistration correction in a unit less than a pixel; and a judgment part, which detects a feature of the image and judges whether or not to execute the misregistration correction in a unit less than a pixel by the gradation conversion part. The judgment part compares the gradation level in an object pixel and a pixel adjacent in a sub-scanning direction, thereby judging whether or not to execute the misregistration correction in a unit less than a pixel. Thus, the invention enables to distinguish an image to be subjected to the registration correction in a unit less than a pixel and an image not to be subjected to such correction in a simple manner and also in consideration of the image color.