Microlens Array Calibration for Ghosting Reduction

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Solution Overview

Problem

Light-field image processing systems face issues with geometric distortion and ghosting due to variations in microlens position, which existing technologies fail to adequately address, leading to artifacts in projected images.

Innovation Solution

The system calibrates microlens positions by identifying disk centers in light-field images, using gridded calibration and displacement vectors to correct geometric distortions and prevent ghosting, by ensuring accurate geometric relationships between microlens arrays and sensor pixels, and employing a technique where disks are separated by a gap to limit calibration errors.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If microlens position variation is present in light-field image processing systems, then the system can capture light-field data, but geometric distortion and ghosting artifacts are introduced in projected images

Engineering Contradiction:

Improvelight-field data capture capabilityVSAvoidprojection accuracy

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The system performs preliminary calibration by identifying disk centers and computing displacement vectors before image processing. This pre-computed calibration data is then used to correct geometric distortions and prevent ghosting during projection, resolving the contradiction between capturing light-field data and maintaining projection accuracy.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system uses feedback from calibration measurements of disk centers to adjust and correct geometric relationships. By measuring actual microlens positions and comparing them with expected positions, the system computes correction vectors that are applied during projection to eliminate artifacts.

Inventive Principle:

Principle #23Feedback

2Productivity

If calibration errors occur in microlens position identification, then processing can continue, but ghosting artifacts are introduced in projected images

Engineering Contradiction:

Improveimage processing continuityVSAvoidghosting artifacts

Core Design Contradiction:

ProductivityVSObject-generated harmful factors

Solution Approach 1:

The system converts the harmful effect of calibration errors into a manageable geometric distortion problem. By separating disks with gaps and using displacement vectors, it ensures that calibration errors only cause geometric distortion rather than ghosting, allowing processing to continue while minimizing harmful artifacts.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The system provides beforehand cushioning by computing displacement vectors that compensate for expected calibration errors. The gap separation technique creates a buffer zone that prevents small calibration errors from causing ghosting, allowing continuous processing without artifact introduction.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Object-generated harmful factors

If disks are separated by a gap to limit calibration errors, then ghosting is prevented, but geometric distortion may occur

Engineering Contradiction:

Improveghosting eliminationVSAvoidgeometric accuracy

Core Design Contradiction:

Object-generated harmful factorsVSShape

Solution Approach 1:

The system applies dynamic correction using displacement vectors that are computed based on actual calibration data. Rather than a static fixed arrangement, the geometric relationships are dynamically adjusted for each disk based on measured position deviations, allowing simultaneous prevention of ghosting and maintenance of geometric accuracy.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system changes the geometric parameters by computing displacement vectors that adjust disk positions based on calibration errors. By modifying position parameters dynamically and applying correction factors, the system maintains geometric accuracy while preventing ghosting through gap separation.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS9172853B2Microlens array architecture for avoiding ghosting in projected images

Publication Date: 2015.10.27 GOOGLE LLC

AI summary

Light-field image data is processed in a manner that reduces projection artifacts in the presence of variation in microlens position by calibrating microlens positions. Approximate centers of disks in a light-field image are identified, and gridded calibration is performed, by fitting lines to disk centers along orthogonal directions, and then fitting a rigid grid to the light-field image. For each grid region, a corresponding disk center is computed, and a displacement vector is generated. For each grid region, the final disk center is computed as the vector sum of the grid region's geometric center and displacement vector. Calibration data, including displacement vectors, is then used in calibrating disk centers for more accurate projection of light-field images. In at least one embodiment, the imaging geometry is arranged so that disks are separated by a gap, so as to limit or eliminate ghosting.