Image Processing Device Density Correction Without Test Chart
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Solution Overview
Problem
Existing image forming devices face challenges in detecting and correcting density unevenness without using a special test chart or constant density region, which disrupts normal operations and requires downtime for measurement.
Innovation Solution
An image processing device that calculates input/output gradation characteristics for each phase of rotating or circulating members in the image forming device, using pre-output and post-output image data to generate correction data and correct density unevenness without the need for a test chart or constant density region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a test chart is used to detect and correct density unevenness, then measurement precision is improved, but productivity deteriorates due to device downtime and resource consumption
Solution Approach 1:
The image forming device uses its own normal image output to perform density unevenness detection and correction. The device forms an image using its image forming unit, reads it back with an image reading unit, and processes the data through the image processing unit to generate correction values. This self-service approach eliminates the need for separate test charts and dedicated measurement time, allowing continuous operation while maintaining measurement precision.
2Measurement precision
If a test chart is used to detect density unevenness, then measurement precision is improved, but loss of time increases due to required downtime for measurement
Solution Approach 1:
The system enables continuous image forming operation by integrating density unevenness detection and correction into the normal image processing workflow. The image processing unit calculates correction values based on pre-output image data and post-output scanned data, applying corrections without interrupting the image forming process. This eliminates the need to stop the device for measurement, maintaining continuous productive operation.
3Measurement precision
If a constant density region is required in image data for detection, then measurement precision is improved, but adaptability deteriorates when processing images without uniform regions
Solution Approach 1:
The image processing unit processes arbitrary image data by analyzing the relationship between pre-output image data and post-output scanned data. Instead of requiring constant density regions, the system calculates correction values based on the actual image content and its scanned counterpart. This parameter-based approach allows the system to handle diverse image types including photographs and complex graphics without needing uniform density regions, thereby improving adaptability while maintaining correction accuracy.
Data Source
AI summary
Provided is an image processing device used for image processing in an image forming device that executes linear image forming in a first direction repeatedly in a second direction orthogonal to the first direction and executes two-dimensional image forming on a recording medium, the image processing device including: a processor configured to: acquire a phase of a member that contributes to image forming by rotating or circulating in the second direction and calculate, for each of different phases, an input/output gradation characteristic indicating a correspondence relationship in density in the same pixels in pre-output image data and post-output image data acquired by scanning of an image formed on the recording medium; calculates correction data to solve a difference between the input/output gradation characteristic in each of the phases and a reference input/output gradation characteristic; and correct the pre-output image data with the correction data of each of the phases.