Pixel Value Correction for Spectral Sensitivity Variations
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Solution Overview
Problem
Existing imaging systems face challenges in accurately correcting variations in spectral sensitivity across pixels in image sensors, leading to inconsistencies in color representation, particularly due to differences in spectral transmittance of color filters.
Innovation Solution
An image processing apparatus is designed to calculate and apply correction coefficients to pixel values based on the spectral sensitivity of surrounding pixels of the same color, using a correction amount calculation unit and pixel value correction unit to adjust pixel values and improve color representation accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If correction coefficients are calculated using only the pixel-of-interest's own data, then the correction process is simple, but the color representation accuracy is insufficient due to spectral sensitivity variations
Solution Approach 1:
The patent applies local quality by using the spectral characteristics of surrounding pixels of the same color to calculate correction coefficients specifically for the pixel-of-interest. This localized approach uses neighboring pixel data (e.g., adjacent red pixels for a red pixel correction) to create position-specific correction values, improving color accuracy while maintaining computational efficiency by limiting the scope to local neighborhood rather than global processing.
2Measurement precision
If correction coefficients are calculated using surrounding pixel data, then color representation accuracy improves, but the calculation complexity increases
Solution Approach 1:
The patent segments the correction process by separating pixels into different color groups (red, green, blue) and processing each group independently. For each pixel-of-interest, only surrounding pixels of the same color are used for correction coefficient calculation. This segmentation reduces the number of calculations required compared to using all surrounding pixels, thereby improving accuracy through multi-pixel data while controlling calculation complexity through group-based processing.
3Reliability
If standard correction methods are applied uniformly to all pixels, then the processing is efficient, but spectral sensitivity variations between pixels are not adequately corrected
Solution Approach 1:
The patent changes the correction parameter from a uniform correction value applied to all pixels to position-specific correction coefficients calculated individually for each pixel-of-interest based on its surrounding pixels' spectral characteristics. This parameter change enables adequate correction of spectral sensitivity variations by adapting the correction value to each pixel's local environment, while the automated calculation process maintains processing efficiency without requiring manual intervention.
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 solution effectively corrects spectral sensitivity variations across pixels, enhancing the accuracy and consistency of color representation in images by utilizing surrounding pixel values and correction coefficients, thereby improving image quality.
Implementation Method 1
visible light spectrally split by a prism is photoelectrically converted by an image sensor to calculate values of red (R), green (G), and blue (B) components
Data Source
AI summary
An image processing apparatus includes: an acquisition unit configured to obtain image data generated by an image sensor forming an array pattern using color filters having mutually different spectral transmittances and to obtain a correction coefficient for correcting a difference between pixel values corresponding to a difference between a spectral sensitivity and a preset reference spectral sensitivity in a wavelength range in a pixel-of-interest; a correction amount calculation unit configured to calculate an estimation value of a color component in the pixel-of-interest using a pixel value of each of pixels in surrounding pixels of a same color and the correction coefficient and configured to calculate a correction amount of the pixel value of the pixel-of-interest based on the estimation value and the correction coefficient of the pixel-of-interest; and a pixel value correction unit configured to correct the pixel value of the pixel-of-interest based on the calculated correction amount.