Learned Image Processing Pipeline for CFA Adaptation

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Solution Overview

Problem

Modern digital cameras with high megapixel counts face challenges in effectively processing images due to diffraction and aberrations, limiting the use of high spatial sampling, and existing image processing algorithms struggle to adapt to new color filter array (CFA) designs, particularly in demosaicking, denoising, and color transformation.

Innovation Solution

The development of a local, linear, learned image processing pipeline (L3) that uses machine learning to automatically calculate filters and parameters from a training set, allowing for efficient demosaicking, denoising, and color transformation, adaptable to various CFAs and applications, by exploiting statistical correlations between input and output images.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If high spatial sampling is used in high megapixel cameras, then image resolution is improved, but diffraction and aberrations from optics blur the image at the sensor

Engineering Contradiction:
Improveimage resolutionVSAvoidimage quality
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The patent introduces an intermediate computational processing stage that acts as a mediator between the blurred sensor output and the final image. The demosaicking algorithm with adaptive filtering and machine learning-based post-processing serves as this intermediary, recovering lost high-frequency information and reducing artifacts to compensate for optical limitations.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces purely optical/mechanical image formation with a hybrid approach that substitutes computational processing for optical perfection. Instead of relying solely on optical quality to achieve sharp images, the system uses algorithms to synthetically restore and enhance image details that would otherwise be lost to diffraction and aberrations.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Productivity

If traditional image processing algorithms are used, then processing speed is maintained, but they struggle to adapt to new color filter array (CFA) designs

Engineering Contradiction:
Improveprocessing speedVSAvoidadaptability to CFA designs
Core Design Contradiction:
ProductivityVSAdaptability or versatility

Solution Approach 1:

The patent implements dynamic adaptability by training machine learning models on diverse CFA patterns and applying the appropriate model based on the detected CFA type. The system dynamically adjusts its processing parameters, filtering strategies, and demosaicking approaches according to the specific CFA design being used, rather than relying on fixed algorithms.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent changes key processing parameters based on the CFA configuration, including filter kernel sizes, regularization strengths, and color space transformation matrices. By adapting these parameters to match the specific CFA pattern, the system maintains high processing efficiency while achieving accurate results across different sensor designs.

Inventive Principle:
Principle #35Parameter changes

3Device complexity

If simple demosaicking algorithms are used, then processing complexity is reduced, but color accuracy and image quality deteriorate

Engineering Contradiction:
Improveprocessing complexityVSAvoidcolor accuracy
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The patent segments the demosaicking process into distinct stages: initial interpolation, adaptive filtering, artifact reduction, and color correction. Each stage handles a specific aspect of the problem with targeted processing, achieving high color accuracy through specialized operations rather than a single complex algorithm.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent introduces intermediate processing steps that act as mediators between the simple demosaicking output and the final high-quality image. These include adaptive filtering stages and machine learning-based refinement that progressively improve color accuracy without requiring the initial demosaicking algorithm to be highly complex.

Inventive Principle:
Principle #24Intermediary (Mediator)

Data Source

PatentUS8675105B2Learning of image processing pipeline for digital imaging devices
Publication Date: 2014.03.18 THE BOARD OF TRUSTEES OF THE LELAND STANFORD JUNIOR UNIV
  • US8675105B2 patent drawing
  • US8675105B2 patent drawing
  • US8675105B2 patent drawing

AI summary

A learning technique is provided that learns how to process images by exploiting the spatial and spectral correlations inherent in image data to process and enhance images. Using a training set of input and desired output images, regression coefficients are learned that are optimal for a predefined estimation function that estimates the values at a pixel of the desired output image using a collection of similarly located pixels in the input image. Application of the learned regression coefficients is fast, robust to noise, adapts to the particulars of a dataset, and generalizes to a large variety of applications. The invention enables the use of image sensors with novel color filter array designs that offer expanded capabilities beyond existing sensors and take advantage of typical high pixel counts.