Sweeping Correction for Compressed Image Data Blocks
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Solution Overview
Problem
Existing image processing methods for electrophotographic image forming apparatuses face challenges in applying sweeping correction to compressed image data, leading to unstable output and increased circuit complexity due to the need for parallel processing of compressed and decompressed data.
Innovation Solution
An image processing apparatus that calculates a sweeping correction value from compressed image data and applies it to decompressed data using an extractor, edge detector, correction value calculator, and converter to determine and apply the necessary pixel value conversions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If sweeping correction processing is applied to compressed image data in parallel with other image processing, then processing efficiency is improved, but output stability deteriorates due to range changes between minimum and maximum values
Solution Approach 1:
The patent applies sweeping correction to the maximum and minimum values of compressed image data blocks before decompression. By performing the correction action in advance on the compressed data, the system maintains processing efficiency while ensuring that the correction results are preserved through subsequent decompression and other image processing operations, thus maintaining output stability.
Solution Approach 2:
The patent changes the approach from correcting pixel values after decompression to correcting the maximum and minimum value parameters of compressed blocks before decompression. This parameter-level correction on compressed data allows parallel processing while maintaining stability, as the corrected maximum and minimum values guide the decompression process to produce stable output.
2Manufacturing precision
If line memories are increased to cope with high-resolution image data for sweeping correction, then image quality is improved, but cost increases due to more line memories required
Solution Approach 1:
The patent changes the resolution handling approach by performing sweeping correction on compressed image data at lower resolutions before decompression. This allows the system to achieve high-quality output without requiring large amounts of line memory proportional to the final high resolution, thereby reducing cost while maintaining image quality.
Solution Approach 2:
The patent works with compressed representations (a form of copy) of the image data rather than full-resolution data throughout the processing pipeline. By performing sweeping correction on the compressed block maximum and minimum values, the system achieves the correction effect without needing to store and process full high-resolution data, reducing memory requirements and cost.
3Reliability
If sweeping correction is applied after decompression, then output stability is maintained, but processing complexity increases and circuit size grows
Solution Approach 1:
The patent performs sweeping correction on the maximum and minimum values of compressed blocks before decompression occurs. By taking this preliminary action on the compressed data, the system eliminates the need for separate correction circuits after decompression, reducing overall circuit complexity and size while maintaining output stability through the corrected decompression process.
Data Source
AI summary
An image processing apparatus includes: an extractor that divides image data in block units and extracts a maximum value and a minimum value of each block from the compressed image data; an edge detector that detects an edge at a front end or a rear end of an image; a correction value calculator that corrects the maximum value, or the maximum value and the minimum value of each block positioned in a certain range from the front end or the rear end and calculates a maximum value and a minimum value after the correction; and a converter that determines a conversion formula of a pixel value by using the maximum value and the minimum value before the correction and the maximum value and the minimum value after the correction and converts each pixel value of the image data obtained by decompressing the compressed data so as to apply sweeping correction.