Color Imaging Device Using Weighted Average Filters
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Solution Overview
Problem
Existing color imaging apparatuses face challenges in suppressing false color generation, particularly in high-frequency sections, due to complications in image processing and ineffective arrangements of color filters, which lead to color moire issues.
Innovation Solution
A color imaging apparatus with a single-plate color imaging element featuring a color filter array where all colors are periodically arranged in horizontal and vertical directions, using weighted average filters with predetermined filter coefficients to ensure equal proportions of filter coefficients in each line, allowing for accurate interpolation of pixel values based on color ratios or differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If an optical low-pass filter is arranged on the front side of the color imaging element to prevent high frequency wave reduction, then color moire is reduced, but resolution is reduced accordingly
Solution Approach 1:
The patent removes the optical low-pass filter from the optical path and extracts the color moire suppression function to the image processing unit through digital signal processing. The high-pass filter processing in the image processing unit selectively attenuates only the color moire frequency components while preserving the resolution of the captured image.
Solution Approach 2:
The patent replaces the mechanical/optical low-pass filter with an electronic/digital signal processing system. Instead of using physical filtering in the optical path, the invention uses digital high-pass filter processing to suppress color moire, thereby eliminating the trade-off between color moire suppression and resolution loss.
2Object-affected harmful factors
If a three-color random array is used to address low-frequency color moire, then low-frequency color moire is suppressed, but false color in high-frequency sections occurs
Solution Approach 1:
The patent changes the frequency response parameters of the signal processing system by applying high-pass filter processing with specific frequency characteristics. This selectively suppresses color moire in certain frequency ranges while preserving high-frequency image components, thereby avoiding false color generation in high-frequency sections.
3Measurement precision
If complex synchronization processing is performed to estimate pixel values, then color accuracy is improved, but image processing complexity increases
Solution Approach 1:
The patent performs preliminary color correction and high-pass filter processing on the RAW image data before synchronization processing. By pre-processing the image data to correct color deviations and enhance edge information, the subsequent pixel value estimation requires simpler calculations while achieving the same or better color accuracy.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively suppresses false color generation in high-frequency sections by ensuring consistent color relationships and accurate pixel value estimation, simplifying image processing and maintaining resolution without the need for optical low-pass filters.
Implementation Method 1
a plurality of pixels formed by photoelectric conversion elements arranged in horizontal and vertical directions
Data Source
Figure 1~2
Figure 3~4
Figure 5~6A
AI summary
A single-plate color imaging element including color filters having a color filter array where the color filters of all RGB colors are periodically arranged in each line in the horizontal and vertical directions is used. Weighted average filters including filter coefficients with equal proportions of sums of the filter coefficients of each color in the lines in the horizontal and vertical directions are used to calculate weighted average values of each color of the pixel values of the pixels in a mosaic image output from the color imaging element. In the calculation of the pixel value of another color at the pixel position of a target pixel of synchronization processing at a center section of the weighted average filters, the pixel value of the target pixel is interpolated based on a color ratio or a color difference of the calculated weighted average values to estimate the pixel value of the another color.