Image Forming Apparatus Gamma Correction Memory Reduction
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Solution Overview
Problem
Existing electrophotographic image forming apparatuses face challenges in efficiently correcting gamma characteristics due to photoconductor drum deterioration and environmental changes, leading to uneven density and increased memory requirements and toner consumption for calibration.
Innovation Solution
The apparatus includes a first acquisition unit for reference correction characteristics, a second acquisition unit for relative correction characteristics, and a correction unit that adjusts image data based on these characteristics to correct output density, reducing the need for extensive memory storage and toner usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If gamma correction characteristics are stored for each position for each screen type, then density unevenness is improved, but memory area increases
Solution Approach 1:
The invention divides the gamma correction characteristics into two segments: reference correction characteristics (stored once per screen type) and relative correction characteristics (stored per position). This segmentation allows the system to maintain position-specific density correction while reducing overall memory requirements by avoiding redundant storage of complete correction tables for each screen type.
Solution Approach 2:
The invention extracts the position-dependent correction information from the complete gamma correction characteristics. By separating the reference characteristics (which are common across positions) from the relative characteristics (which vary by position), the system retains only the essential position-specific data needed to correct density unevenness, thereby reducing memory usage.
2Measurement precision
If calibration is performed for each position, then density correction accuracy is improved, but toner consumption increases
Solution Approach 1:
The invention performs preliminary measurement of relative correction characteristics at multiple positions during initial calibration. These pre-measured relative characteristics are stored and reused during normal operation, eliminating the need to repeat full calibration measurements for each position and thereby reducing toner consumption while maintaining calibration accuracy.
Solution Approach 2:
The invention creates a copy of the relative correction characteristics that can be reused. Instead of performing physical calibration measurements repeatedly, the system uses stored copies of the relative correction data to maintain accuracy, thus avoiding additional toner consumption associated with repeated calibration patches.
3Measurement precision
If calibration is performed for each position, then density correction accuracy is improved, but calibration time increases
Solution Approach 1:
The invention performs the time-consuming measurement of relative correction characteristics during initial calibration and stores the results. During subsequent operations, the system retrieves and applies these pre-measured characteristics instantly, avoiding repeated calibration measurements and thereby significantly reducing calibration time while maintaining accuracy.
Solution Approach 2:
The invention creates and stores copies of the relative correction characteristics that can be rapidly accessed and applied without repeating the original measurement process. This copying approach allows the system to maintain calibration accuracy while dramatically reducing the time required for subsequent calibration operations.
4Measurement precision
If reference correction characteristics are stored for each screen type, then gamma correction accuracy is improved, but memory area increases
Solution Approach 1:
The invention makes the reference correction characteristics universal by storing them only once per screen type rather than for each position. These reference characteristics serve multiple positions universally, and the position-specific variations are captured separately in relative correction characteristics, achieving both accuracy and memory efficiency.
Solution Approach 2:
The invention merges the common reference correction characteristics across all positions into a single storage location per screen type. By combining these universal characteristics with the position-specific relative characteristics, the system achieves complete gamma correction accuracy while minimizing redundant storage and reducing overall memory requirements.
Data Source
AI summary
An image forming apparatus of the present invention acquires first correction characteristics representing an output density for an input gradation value at a reference position in a main scanning direction and second correction characteristics representing a relative relationship of an output density at a predetermined position in the main scanning direction with the output density at the reference position in the main scanning direction. Then, the image forming apparatus corrects image data corresponding to the predetermined position in the main scanning direction based on the first correction characteristics and the second correction characteristics.