Liquid Crystal Shutter Coded Aperture for Single-Shot Depth Map Generation

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Solution Overview

Problem

Existing methods for generating depth maps using coded apertures require capturing images twice, restricting their application to static scenes and making it difficult to capture moving images.

Innovation Solution

A system that uses a liquid crystal shutter to form a coded aperture with a specific aperture pattern, allowing for the capture of a depth map in a single image by utilizing a coded aperture part with a first area of high light transmittance, a second area of lower transmittance, and a third area of even lower transmittance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If two coded apertures are used to generate depth map, then the filter can be prevented from having zero power spectrum frequency band, but the number of image captures increases to two, restricting application to static scenes

Engineering Contradiction:

Improvedepth map generation reliabilityVSAvoidimage capture time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent combines the functions of two separate coded apertures into a single coded aperture by superimposing their aperture patterns. This merging allows the single aperture to provide the combined optical transfer function benefits of both original apertures, enabling reliable depth map generation from a single image capture without requiring sequential captures with two different apertures.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent pre-calculates and superimposes the aperture patterns of two coded apertures before actual image capture. By preparing the combined aperture pattern in advance, the system eliminates the need for sequential captures, allowing single-shot depth map generation while maintaining the reliability benefits of using multiple aperture characteristics.

Inventive Principle:

Principle #10Preliminary action

2Measurement precision

If two coded apertures are used to generate depth map, then the filter quality is improved, but the operational speed decreases making it difficult to capture moving images

Engineering Contradiction:

Improvedepth measurement precisionVSAvoidimage capture speed

Core Design Contradiction:

Measurement precisionVSSpeed

Solution Approach 1:

The patent merges the functional benefits of two coded apertures into one superimposed aperture pattern, allowing the system to achieve the depth measurement precision normally requiring two separate captures, but now from a single capture. This merging maintains measurement precision while doubling the effective capture speed.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent changes the aperture pattern parameter by superimposing multiple aperture patterns into a single composite pattern. This parameter transformation allows the single aperture to provide the frequency domain benefits of multiple apertures, improving depth measurement precision without the time penalty of sequential captures.

Inventive Principle:

Principle #35Parameter changes

3Speed

If the exposure time is shortened to capture moving images, then the capture speed increases, but the image quality and depth map accuracy deteriorate

Engineering Contradiction:

Improvecapture speedVSAvoiddepth measurement precision

Core Design Contradiction:

SpeedVSMeasurement precision

Solution Approach 1:

The patent combines the information content of two coded aperture patterns into a single pattern, allowing the system to extract depth information with high precision from a single short-exposure image. The superimposed aperture pattern provides sufficient frequency domain information to maintain depth measurement accuracy even with reduced exposure time.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent enables continuous depth map generation by using a single aperture pattern that inherently provides the information equivalent of two sequential captures. This continuous action approach allows for high-speed capture of moving images without the interruption and time loss associated with sequential dual-aperture captures.

Inventive Principle:

Principle #20Continuity of useful action

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

Enables the generation of depth maps from a single image capture, expanding the applicability to dynamic scenes and improving operational efficiency.

Implementation Method 1

An aperture pattern of the coded aperture part includes a first area having a first light transmittance, a second area having a second light transmittance lower than the first light transmittance, and a third area having a third light transmittance lower than the second light transmittance

Methodology Applied

Scientific EffectLight transmittance control: Absorption (EM radiation)

Data Source

PatentUS20250117954A1System, method, and information storage medium storing program for generating depth maps

Publication Date: 2025.04.10 JAPAN DISPLAY INC

AI summary

A generation system includes a liquid crystal shutter that forms a coded aperture part and a depth calculating unit that uses a captured image acquired by an imaging device to calculate a depth for each unit area of a depth map. The coded aperture part includes an aperture pattern including a transmissive area having a first light transmittance, a semi-transmissive area having a second light transmittance lower than the first light transmittance, and a shielding area having a third light transmittance lower than the second light transmittance. This serves to reduce the number of times of capturing an object required for generating a depth map, thereby increasing situations in which the generation system is used.