Colorimetry Calibration via Dual-Reader Patch Segmentation
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Solution Overview
Problem
Conventional image forming apparatuses face challenges in accurately calibrating scanners due to flare and surface irregularities, leading to errors in color measurement and correction, which affects the accuracy of color correction in image output.
Innovation Solution
An image forming apparatus with a first reader for reading a partial region and a second reader for reading the entire region, using an adjustment pattern with distinct patch regions, where the hardware processor converts and corrects color values to achieve accurate colorimetry by comparing readings from both readers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a scanner reads patches in the common reading region, then color measurement can be performed, but measurement accuracy deteriorates due to flare and surface irregularities
Solution Approach 1:
The patent divides the reading region into two distinct areas: a first reading region where only the colorimeter reads patches, and a second reading region where both the scanner and colorimeter read patches. This segmentation allows the system to separately measure and correct for scanner errors in the second region while maintaining efficient full-region scanning in the first region.
Solution Approach 2:
The patent introduces an intermediary correction process that uses the second reading region as a calibration zone. By comparing scanner and colorimeter readings in this intermediate region, the system calculates correction values that mediate between the scanner's rapid but inaccurate measurements and the colorimeter's accurate but slower measurements.
2Manufacturing precision
If the scanner is adjusted using colorimeter readings from the common reading region, then color correction can be performed, but measurement accuracy deteriorates due to flare influence
Solution Approach 1:
The patent extracts the problematic common reading region from the calibration process and replaces it with a dedicated second reading region. This extraction removes the flare contamination that plagues the common region, allowing for accurate scanner-colorimeter comparison without the harmful influence of flare on white patches.
Solution Approach 2:
The patent converts the harmful effect of flare into a beneficial calibration opportunity. By deliberately placing patches in the second reading region where both devices can read, the system uses the flare-induced measurement differences to calculate and store correction values, transforming the harmful flare effect into a useful calibration signal.
3Area of stationary object
If a single reader reads the entire region, then measurement coverage is complete, but measurement accuracy deteriorates due to surface irregularities
Solution Approach 1:
The patent segments the reading area into two functional zones: the first reading region for colorimeter-only measurement and the second reading region for dual-device calibration. This segmentation enables complete area coverage while maintaining measurement precision through targeted dual-reading in the calibration zone.
Data Source
AI summary
An image forming apparatus that prints an adjustment pattern on a sheet includes a generator and an image former. The adjustment pattern is for correcting a color value obtained by reading a second patch region on the sheet with a second reader based on a color value obtained by reading a first patch region on the sheet with a first reader. The generator generates image data of the adjustment pattern, and the image former performs printing based on the image data. The adjustment pattern includes a first patch printed in the first patch region and a second patch printed in a region other than the first patch region in the second patch region. The second patch includes a common color patch in a same color as a color of the first patch, and a size of the first patch is larger than a size of the second patch.