Image Processing Using Sparse Representation for Depth of Field Extension

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Solution Overview

Problem

Current digital camera systems face limitations in improving image quality due to optical constraints, particularly in smartphones, where the increasing pixel density is bounded by optical system limitations, and software advancements are needed to enhance depth of field (DOF) without the practicality of optical solutions.

Innovation Solution

The method involves decomposing images into multiple channels with different depth-of-field characteristics, using an optical mask or digital processing to capture images, and employing in-focus and out-of-focus dictionaries to compute sparse representations, allowing for improved image representation and restoration without prior knowledge of the blurring kernel.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If pixel number and density are increased, then imaging system resolution is improved, but optical system limitation becomes the binding constraint

Engineering Contradiction:
Improveimaging system resolutionVSAvoidoptical system limitation
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces optical mechanical solutions with computational processing. Instead of improving resolution through optical hardware (lens quality, aperture size), the system uses digital image processing techniques including sparse representation, dictionary learning, and multi-channel fusion to overcome optical limitations and achieve higher effective resolution.

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

Solution Approach 2:

The patent changes the parameter space by decomposing images into multiple channels (e.g., color channels, frequency channels, or focus channels) and processing them differently. By transforming the image into alternative representations and combining results, the system achieves resolution enhancement without physical optical changes.

Inventive Principle:
Principle #35Parameter changes

2Measurement precision

If optical solutions are used to improve image quality, then image quality is enhanced, but device volume constraints in smartphones make it difficult

Engineering Contradiction:
Improveimage qualityVSAvoiddevice volume
Core Design Contradiction:
Measurement precisionVSVolume of moving object

Solution Approach 1:

The patent substitutes optical hardware solutions with software-based image processing. Instead of adding larger lenses, multiple lenses, or complex optical mechanisms that would increase device volume, the system uses computational algorithms to enhance image quality while maintaining compact form factor.

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

Solution Approach 2:

The patent extracts and processes different components of the image separately (e.g., separating in-focus and out-of-focus regions, decomposing into frequency bands or color channels). By isolating and independently processing these components, the system achieves quality enhancement without requiring additional physical components.

Inventive Principle:
Principle #2Taking out (Extraction)

3Adaptability or versatility

If multiple channels with different depth-of-field are used, then depth of field is extended, but image processing complexity increases

Engineering Contradiction:
Improvedepth of fieldVSAvoidimage processing complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent segments the image processing task into distinct stages: decomposition into multiple channels, independent processing of each channel, and fusion of results. By dividing the complex task of extending depth of field into manageable segments, the system achieves the goal while controlling processing complexity through modular architecture.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent introduces intermediate representations (such as sparse codes, dictionary atoms, or transformed channel data) that facilitate the combination of multiple channels with different depth-of-field characteristics. These intermediaries enable efficient fusion and simplify the overall processing complexity.

Inventive Principle:
Principle #24Intermediary (Mediator)

Data Source

PatentUS11257229B2Method and system for processing an image
Publication Date: 2022.02.22 RAMOT AT TEL AVIV UNIVERSITY LTD
  • US11257229B2 patent drawing
  • US11257229B2 patent drawing
  • US11257229B2 patent drawing

AI summary

A method of processing an image is disclosed. The method comprises decomposing the image into a plurality of channels, each being characterized by a different depth-of-field, and accessing a computer readable medium storing an in-focus dictionary defined over a plurality of dictionary atoms, and an out-of-focus dictionary defined over a plurality of sets of dictionary atoms, each set corresponding to a different out-of-focus condition. The method also comprises computing one or more sparse representations of the decomposed image over the dictionaries.