Camera Lens Focus Calibration for Object Distance Estimation

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Solution Overview

Problem

Existing camera auto-focus mechanisms, such as contrast auto-focus, rely on passive technology and require costly mechanisms like lasers or AI to accurately determine object distance, which is inefficient and undesirable for achieving sharp images.

Innovation Solution

A method for estimating object distance using a single camera by capturing calibration data during a calibration phase, where the relationship between in-focus lens positions and object distances is stored, allowing for future lookup and interpolation to determine object distance without lasers or AI, using contrast measurements and non-linear interpolation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If contrast auto-focus mechanism is used to determine focus position, then image sharpness is improved, but object distance estimation accuracy deteriorates without additional costly mechanisms

Engineering Contradiction:

Improveimage sharpnessVSAvoidobject distance estimation accuracy

Core Design Contradiction:

Manufacturing precisionVSMeasurement precision

Solution Approach 1:

The patent performs preliminary calibration by capturing images at multiple known object distances and storing the relationship between lens positions and object distances in a lookup table. This preliminary action enables accurate object distance estimation during actual operation without requiring additional costly mechanisms like lasers or AI processing.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent creates a calibration lookup table that copies the relationship between lens positions and object distances from controlled calibration conditions. This copied data structure allows the system to estimate object distances in real operation by simply looking up the measured lens position in the pre-created table, avoiding the need for complex real-time calculations or additional hardware.

Inventive Principle:

Principle #26Copying

2Measurement precision

If costly mechanisms like lasers or AI are used to determine object distance, then object distance estimation accuracy is improved, but device complexity and cost increase

Engineering Contradiction:

Improveobject distance estimation accuracyVSAvoiddevice complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces expensive, complex mechanisms (lasers, AI processing units) with a simple calibration lookup table stored in memory. This approach uses inexpensive data structures instead of costly hardware or computational resources, achieving accurate object distance estimation without increasing device complexity.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent substitutes complex mechanical or computational systems (lasers, AI algorithms) with a simple data lookup operation. The calibration lookup table replaces the need for active ranging mechanisms or sophisticated image processing, significantly reducing device complexity while maintaining measurement accuracy.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Measurement precision

If calibration data is captured for multiple object distances, then object distance estimation accuracy is improved, but calibration time and processing duration increase

Engineering Contradiction:

Improveobject distance estimation accuracyVSAvoidcalibration time

Core Design Contradiction:

Measurement precisionVSDuration of action of moving object

Solution Approach 1:

The patent performs the time-consuming calibration process in advance, capturing images at multiple known object distances and building the lookup table before actual operation. This preliminary action separates the calibration phase from the operational phase, so that accurate object distance estimation during use requires only fast lookup operations rather than lengthy calibration procedures.

Inventive Principle:

Principle #10Preliminary 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 accurate estimation of object distance in real-time image capture without costly mechanisms, ensuring sharp images and efficient operation by utilizing stored calibration data and contrast measurements.

Implementation Method 1

A camera typically includes an adjustable focus mechanism to adjust the lens settings to cause an image to be in focus

Methodology Applied

Scientific EffectOptical focusing: Lens

Implementation Method 2

A contrast auto-focus mechanism uses the image signal to determine the focus position by measuring the intensity difference between adjacent pixels of the captured image

Methodology Applied

Scientific EffectLight field contrast: Light

Data Source

PatentUS20230319429A1Object distance estimation with camera lens focus calibration

Publication Date: 2023.10.05 ADVANCED MICRO DEVICES INC

AI summary

Systems, apparatuses, and methods for estimating object distance with camera lens focus calibration are disclosed. A relationship between in-focus lens position and object distance is captured in a calibration phase for a plurality of object distances and lens positions for a given camera. The in-focus lens positions and corresponding object distances are stored as calibration data in a memory device of the given camera. Next, during operation of the given camera, a control circuit receives the in-focus lens position that was used to capture a given image. Then, the control circuit performs a lookup of the calibration data with the in-focus lens position to retrieve a corresponding object distance. Next, the corresponding object distance is used as an estimate of a distance to an object in the scene captured in the given image by the given camera.