Pseudo-color suppression in single-chip CCD image processing
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Solution Overview
Problem
Traditional image processing methods using single-chip CCDs with Bayer color filters face challenges in suppressing pseudo-color without losing image resolution, as optical filters can cut off correct signal constituents and mistaken color stripes can reduce color saturation.
Innovation Solution
An image processing device and method that generates a color image by synchronizing R, Gr, and B pixel signals to produce luminance and color differences, with pseudo-color suppression using specific parameters to target high-frequency components in oblique and horizontal/vertical directions, and applying a low-frequency pass filter to remove noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If an optical filter with cut-off frequency of fs/2 is placed between the lens and CCD to prevent pseudo-color, then pseudo-color is suppressed, but correct signal constituents are cut off and image quality deteriorates
Solution Approach 1:
The patent replaces the optical filter (mechanical/optical system) with a signal processing approach. Instead of physically filtering light before it reaches the CCD, the invention processes the electrical signals after photoelectric conversion to suppress pseudo-color artifacts. This substitution allows preserving high-frequency signal constituents that would be blocked by an optical filter while still eliminating pseudo-color effects through digital signal manipulation.
Solution Approach 2:
The patent introduces an intermediate signal processing step between the CCD output and final image generation. By adding a pseudo-color suppression processing unit that operates on the electrical signals, it creates an intermediary mechanism that can selectively remove pseudo-color components without affecting the underlying image information, thus resolving the contradiction between pseudo-color suppression and image quality preservation.
2Ease of operation
If only interpolation processing is performed on color mosaic image, then color image can be generated, but pseudo-color generation or loss of image resolution occurs
Solution Approach 1:
The patent segments the image processing into distinct functional units: a color mosaic image generation unit that performs interpolation to create the initial color image, and a separate pseudo-color suppression processing unit that refines the result. This segmentation allows each unit to perform its specific function optimally - the first generates the color image through interpolation, while the second corrects the pseudo-color artifacts without degrading resolution.
3Object-affected harmful factors
If pseudo-color suppression is performed by comparing difference of nearby pixel signals near image edge, then pseudo-color is suppressed, but color stripes that are not pseudo-color are mistakenly reduced resulting in loss of color saturation
Solution Approach 1:
The patent implements a feedback mechanism in the pseudo-color suppression processing unit that analyzes the characteristics of signal variations to distinguish between pseudo-color artifacts and legitimate color information. By using feedback from the processed signals to adjust the suppression intensity, the system can selectively remove pseudo-color while preserving genuine color saturation, avoiding the mistaken reduction of valid color stripes.
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
Effectively suppresses pseudo-color without degrading resolution, producing high-quality color images by precisely targeting and reducing pseudo-color signals in the color differences, resulting in enhanced image quality.
Implementation Method 1
an imaging system wherein the photographed image goes through the lens, forms an image on the CCD where the subject image is photo electrically converted and an image signal is generated
Data Source
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Figure 2(a)~2(c)
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AI summary
An image processing device comprising - a synchronization unit (25) for generating a luminance (Y') from the sum of pixel signals R, Gr, Gb, B, for subtracting the R pixel signal and the B pixel signal from the sum of the Gr pixel signal and Gb pixel signal so as to generate a first color difference (C1), and for calculating a difference between the R pixel signal and the B pixel signal to generate a second color difference (C2), - a pseudo-color suppression unit (31) for performing pseudo-color suppression of the first color difference (C1) and/or the second color difference (C2), - a color space conversion unit (37) for converting the luminance Y', the first color difference (C1), the second color difference (C2), into a predetermined color space to generate YUV color information.