Halftone Image Correction Coefficient Low Pass Filtering
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Solution Overview
Problem
Halftone processing after streak/unevenness correction can interfere with high-frequency components of an image, causing moiré patterns that were not present in the original image.
Innovation Solution
An image processing apparatus that determines a correction coefficient based on the recording unit's characteristics, applies low-pass filter processing to reduce high-frequency components, and performs dither processing to convert the image into a halftone image, preventing moiré occurrence during streak/unevenness correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If halftone processing is performed after streak/unevenness correction, then streak/unevenness is corrected, but moiré patterns occur due to interference with high-frequency components
Solution Approach 1:
The patent applies low-pass filtering to the correction coefficients before performing streak/unevenness correction. This preliminary action removes high-frequency components from the correction data, preventing them from interfering with the image during subsequent halftone processing and avoiding moiré pattern generation
Solution Approach 2:
The patent extracts and removes high-frequency components from the correction coefficients through low-pass filtering. By separating these problematic high-frequency components from the correction data, the system can apply correction without introducing moiré patterns while still addressing streak and unevenness issues
Data Source
AI summary
An image processing apparatus configured to convert an input image into a halftone image to be output by a recording unit of an output apparatus includes a determination unit configured to determine a correction coefficient based on a characteristic of the recording unit for each of a plurality of pixels in the input image, a filter processing unit configured to perform filter processing on the correction coefficient using a low pass filter, a correction unit configured to correct a pixel value of each of the plurality of pixels in the input image based on the correction coefficient on which the filter processing has been performed, and a halftone processing unit configured to convert a corrected image output from the correction unit into the halftone image by dither processing. The low pass filter is configured to reduce a high-frequency component depending on the dither processing.