Infrared Illuminator Synchronization for Low-Light Video Capture

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Solution Overview

Problem

Existing camera systems require dedicated light sources for video cameras, which can interfere with depth-sensing cameras and increase costs, while also being inefficient in low-light conditions.

Innovation Solution

A camera system that utilizes the light source of a depth-sensing camera, specifically an infrared illuminator, to illuminate frames captured by a video camera, with a temporal pattern that avoids artifacts and allows for efficient image capture without a separate video camera light source.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If a dedicated light source is added for the video camera, then image capture capability in low-light conditions is improved, but device complexity and cost increase

Engineering Contradiction:
Improveimage capture capabilityVSAvoidsystem complexity
Core Design Contradiction:
Illumination intensityVSDevice complexity

Solution Approach 1:

The infrared illuminator originally designed solely for depth-sensing camera illumination is made to serve dual purposes: it illuminates both the depth-sensing camera and the video camera. This multi-functionality eliminates the need for a separate dedicated light source for the video camera, reducing system complexity and cost while maintaining image capture capability in low-light conditions.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Illumination intensity

If a dedicated light source is added for the video camera, then image capture capability is improved, but manufacturing cost increases

Engineering Contradiction:
Improveimage capture capabilityVSAvoidmanufacturing cost
Core Design Contradiction:
Illumination intensityVSEase of manufacture

Solution Approach 1:

By making the infrared illuminator serve both the depth-sensing camera and video camera, the system eliminates the need to manufacture and assemble a separate dedicated light source. This reduces component count, assembly steps, and overall manufacturing cost while maintaining the ability to capture images in low-light conditions.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Device complexity

If the video camera uses the depth-sensing camera's illuminator, then device complexity is reduced, but image capture quality may deteriorate due to temporal pattern artifacts

Engineering Contradiction:
Improvesystem complexityVSAvoidimage quality
Core Design Contradiction:
Device complexityVSManufacturing precision

Solution Approach 1:

The infrared illuminator operates in a periodic temporal pattern (pulsing) optimized for depth-sensing. The video camera is synchronized to capture frames during specific phases of this periodic illumination cycle, ensuring that images are captured when the illuminator is active. This synchronization approach maintains image quality by ensuring proper illumination while preserving the benefits of using a single shared light source.

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The system implements synchronization mechanisms where the video camera receives timing information about the illuminator's periodic activation pattern. This feedback allows the video camera to adjust its frame capture timing to coincide with the illuminator's active phases, ensuring optimal image capture quality while using the shared infrared illuminator without requiring a dedicated light source.

Inventive Principle:
Principle #23Feedback

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 cost-effective, compact camera designs with reduced interference between light sources and improved image capture in low-light conditions by using the depth-sensing camera's illuminator to illuminate the video camera, ensuring artifact-free frames.

Implementation Method 1

parameterization data associated with the infrared illuminator is obtained, the parameterization data including data indicating a temporal pattern of light emitted by the illuminator

Methodology Applied
Scientific EffectLight emission: Light

Data Source

PatentEP3367661B1Method and system for using light emissions by a depth-sensing camera to capture video images under low-light conditions
Publication Date: 2020.11.25 APPLE INC
  • EP3367661B1 patent drawingFigure 1
  • EP3367661B1 patent drawingFigure 2
  • EP3367661B1 patent drawingFigure 3

AI summary

In general, embodiments of the invention relate to a method for capturing video frames. The method includes obtaining a depth-data frame of an environment using a depth-sensing camera and an infrared illuminator, where the environment is illuminated by an illumination pattern emitted by the infrared illuminator, obtaining, an infrared illuminator parameterization for the illumination pattern emitted by the infrared illuminator, obtaining a desired frame exposure time, based on a desired frame exposure, determining, based on the infrared illuminator parameterization and the desired frame exposure time, an actual frame exposure time, and after determining the actual frame exposure time, obtaining a frame of the environment using the actual frame exposure time using the infrared illuminator with the illumination pattern.