Modified Clear Pixels for Image Sensor Color Balance
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Solution Overview
Problem
Conventional imaging systems with clear pixels suffer from color channel imbalance and noise enhancement due to high sensitivity, requiring high color correction and white-balance coefficients, which can lead to improper color correction and pixel noise if not managed carefully.
Innovation Solution
Incorporating modified clear image pixels with added pigment, such as yellow pigment, in the Bayer mosaic pattern to balance sensitivity and reduce noise, while using chroma de-noising and point filtering to improve image quality and reduce color errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If clear pixels are used to boost light sensitivity, then low-light performance is improved, but color channel imbalance and noise enhancement occur
Solution Approach 1:
The patent applies local quality by modifying only specific clear pixels (designated as clear-red or clear-blue pixels) while keeping other pixels unchanged. This localized modification allows the system to benefit from enhanced light sensitivity in specific regions while maintaining color balance through the unchanged reference pixels, thereby resolving the contradiction between improved light sensitivity and maintained color channel balance.
Solution Approach 2:
The patent changes the optical parameters of selected pixels by replacing green color filters with clear or yellow-tinted materials. This parameter change increases light transmission and sensitivity for those specific pixels while the overall color balance is maintained through computational processing that accounts for the modified pixel characteristics, thus improving low-light performance without sacrificing color accuracy.
2Measurement precision
If high color correction coefficients are used to correct color channel imbalance, then color accuracy is improved, but pixel noise is enhanced
Solution Approach 1:
The patent performs preliminary action by pre-identifying and marking clear or yellow-tinted pixels during image capture, allowing the processing system to apply appropriate correction factors in advance. This preliminary classification enables the system to compensate for the altered optical characteristics of these pixels during processing, achieving accurate color correction without requiring excessive correction coefficients that would amplify noise.
Solution Approach 2:
The patent implements feedback mechanisms where the system continuously monitors and adjusts color correction parameters based on the presence and characteristics of modified pixels. By using feedback from pixel identification to dynamically adjust correction coefficients, the system achieves accurate color reproduction while minimizing noise amplification that would occur with fixed high correction coefficients.
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
The modified clear pixels enhance low-light performance, balance color sensitivity, and reduce noise amplification, resulting in improved image quality and reduced color errors, leading to better luminance performance and final image quality.
Implementation Method 1
In one embodiment, a yellow pigment is added to a clear color filter material used in modified clear image pixels. The yellow pigment may be used to balance color sensitivity and reduce noise.
Implementation Method 2
Chroma de-noising and point filtering may be used to improve image quality and reduce color errors.
Implementation Method 3
Chroma de-noising and point filtering may be used to improve image quality and reduce color errors.
Data Source
AI summary
An image sensor may have an array of image sensor pixels arranged in unit pixel cells each having at least one modified clear image pixel. Each modified clear image pixel may include a modified clear color filter element formed from a transparent material such as an oxide material that is modified with a colored pigment or colored dye such as yellow pigment. Each unit pixel cell may include one or more color pixels of other colors such as red pixels, blue pixels, and green pixels. Image signals such as yellow image signals from the modified clear pixels may be processed along with other color image signals such as red image signals and blue image signals to generate standard red, green, and blue image data. Image processing operations may include chroma demosaicing or point filtering of the image signals from the modified clear image pixels.