Multi-Image Processing for Extended Depth of Field
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Solution Overview
Problem
Conventional imaging devices face challenges in achieving a large depth of field and continuous focus due to limitations in focal length, f-number, and image sensor size, often resulting in parts of an image being out of focus.
Innovation Solution
The system captures multiple images of a scene at different focal distances and combines the sharpest portions using an image processing pipeline, employing techniques like Fourier analysis and motion compensation to create a composite image with enhanced depth of field and high dynamic range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the focal length, f-number, or image sensor size is increased to extend depth of field, then the depth of field is improved, but the equipment complexity and cost increase
Solution Approach 1:
The patent segments the image capture process into multiple discrete image captures at different focal distances. Instead of relying on a single complex optical configuration, the system divides the depth of field problem into multiple focused regions, capturing images at near, mid, and far focal planes separately, then combines them computationally to achieve extended depth of field.
Solution Approach 2:
The patent changes the focal distance parameter across multiple image captures rather than changing optical hardware parameters. By varying the focus position (focal distance) across multiple shots and combining the results, the system achieves extended depth of field without modifying the physical lens or sensor characteristics.
2Reliability
If multiple images are captured and combined to extend depth of field, then image quality is improved, but computational overhead and processing time increase
Solution Approach 1:
The patent performs preliminary alignment and registration of multiple images before the final combination step. Motion compensation and feature matching are conducted in advance to pre-align the images, so that the actual depth of field combination process can proceed efficiently without extensive real-time computation.
Solution Approach 2:
The patent replaces complex real-time optical focusing mechanisms with computational image processing. Instead of using mechanical autofocus systems or complex optical switching, the system uses digital image processing techniques including Fourier analysis, phase correlation, and multi-resolution processing to efficiently combine images and achieve the desired depth of field effect.
3Measurement precision
If auto-focus is used to adjust focus position, then the focused distance is optimized, but the lens may focus at the wrong distance or change focus during image capture
Solution Approach 1:
The patent implements feedback through feature detection and phase correlation analysis. The system detects features across multiple images, calculates phase differences to determine relative motion and focus quality, and uses this feedback information to guide the selection of the best-focused regions from each image for combination into the final extended depth of field image.
Data Source
AI summary
Embodiments of imaging devices of the present disclosure automatically utilize sequential image captures in an image processing pipeline. In one embodiment, control processing circuitry initiates a sequential capture of a plurality of images by an image sensor; and image processing circuitry generates a composite image comprising at least portions of the images.