Phase-Image Autofocus Parallax Estimation Under Noise
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Solution Overview
Problem
Existing imaging devices face challenges in accurately performing autofocus due to noise distortion, which affects the precision of phase-based autofocus functions, making it difficult to achieve accurate focusing.
Innovation Solution
The imaging device incorporates an image processor that calculates evaluation values for candidate parallaxes based on phase images, minimizing the influence of noise by determining a target parallax that aligns the first and second phase images, thereby controlling the lens position for precise focusing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If phase-based autofocus is performed using conventional methods, then focusing speed is improved, but noise distortion reduces measurement precision
Solution Approach 1:
The patent combines multiple phase images (first phase image and second phase image) to calculate evaluation values for candidate parallaxes. By merging information from multiple phase images rather than relying on a single phase image, the system maintains fast focusing speed while improving measurement precision through noise reduction via multiple measurements.
Solution Approach 2:
The patent calculates evaluation values for multiple candidate parallaxes and uses these evaluation values to determine the target parallax that minimizes the difference between phase images. This feedback mechanism allows the system to iteratively refine the focus position based on evaluation results, improving accuracy while maintaining speed through efficient evaluation value calculation.
2Measurement precision
If multiple phase images are processed to reduce noise, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent segments the autofocus process into distinct stages: generating multiple phase images, calculating evaluation values for candidate parallaxes, and determining the target parallax. This segmentation allows the system to process multiple phase images for improved precision while managing complexity through structured, modular processing steps.
Solution Approach 2:
The patent changes the parameter being evaluated from direct phase image comparison to evaluation values that represent the degree of certainty for each candidate parallax. This parameter transformation simplifies the comparison process and reduces computational complexity while maintaining measurement precision through systematic evaluation.
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
The solution enhances autofocus accuracy by reducing noise interference, allowing for faster and more precise focusing by aligning phase images, thus improving the overall performance of the imaging device.
Implementation Method 1
An imaging circuit that includes a lens and is configured to collect a phase signal pair including a first phase signal for an object and a second phase signal for the object
Implementation Method 2
the evaluation value calculator may be configured to calculate the evaluation value set based on phase correlation between the first phase image and the second phase image
Data Source
AI summary
An imaging device includes an evaluation value calculator configured to calculate an evaluation value set including evaluation values corresponding to candidate parallaxes based on a phase image set, and a parallax calculator configured to calculate a target parallax based on the evaluation value set, the target parallax representing a phase shift value that allows to minimize a difference between phase images corresponding to phase signals with respect to an object to be imaged. Each of the evaluation values indicates a degree of certainty that the candidate parallax corresponding to each evaluation value is the target parallax.