Event-Based Camera Autofocus via Point Density Calculation
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Solution Overview
Problem
Event-based cameras lack an autofocus function due to their inability to obtain brightness information, resulting in blurry images and inaccurate data capture when the target object is out of focus.
Innovation Solution
An imaging device with an event-based camera system that includes an imaging element outputting two-dimensional point data, an adjustment mechanism for the light receiving lens, and a control unit that calculates point density to adjust the focal point based on the comparison of current and previous point densities, allowing for autofocus without using brightness information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If event-based camera is used to generate images at higher speed, then image processing speed is improved, but autofocus function is lost due to inability to obtain brightness information
Solution Approach 1:
The patent introduces a beam splitter as an intermediary component that divides the light path from the light receiving lens into two separate paths: one leading to the imaging element for event data capture, and another leading to a brightness information acquisition unit. This mediator enables both high-speed event-based imaging and traditional brightness-based autofocus to operate simultaneously without interfering with each other, thus resolving the contradiction between processing speed and autofocus capability
Solution Approach 2:
The imaging device is designed with multi-functionality by incorporating both an imaging element for event data acquisition and a brightness information acquisition unit (such as a conventional image sensor) that can provide brightness information for autofocus. The system universally handles both event-based high-speed imaging and traditional brightness-based focusing, allowing the device to maintain high processing speed while regaining autofocus functionality through the combined operation of multiple functional components
2Loss of substance
If event data is used instead of brightness information, then data communication volume is reduced, but autofocus capability deteriorates
Solution Approach 1:
The patent segments the data acquisition function into two separate channels: one channel (imaging element) captures only brightness change events to minimize data communication volume, while the other channel (brightness information acquisition unit) captures full brightness information specifically for autofocus purposes. This segmentation allows the system to maintain low overall data transmission by using event data for primary imaging while obtaining precise focus measurement data through the dedicated brightness acquisition path
Solution Approach 2:
The beam splitter acts as an intermediary that separates the light signal into two paths, enabling independent optimization of each data stream. The event data path maintains minimal data volume by transmitting only brightness change information, while the brightness information path provides sufficient data for accurate autofocus measurement, thus resolving the contradiction between data reduction and measurement precision
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 autofocus functionality in event-based cameras by adjusting the focal point based on point density calculations, improving image clarity and reducing unnecessary adjustments, thus enhancing image processing speed and accuracy.
Implementation Method 1
an imaging element that outputs event data including two-dimensional point data corresponding to pixels whose brightness has changed when receiving light
Implementation Method 2
an adjustment mechanism that adjusts a focal point of the light receiving lens
Data Source
AI summary
An imaging device in which an autofocus function can be performed without using brightness information is provided. In an imaging device according to one aspect, a density of points obtained by plotting two-dimensional point data of a plurality of event data as points on a plane, the event data outputted from an imaging element in a predetermined period in a state in which a focal point of a light receiving lens is adjusted by an adjustment mechanism, is calculated as a point density. When the point density is calculated, a control unit drives and controls the adjustment mechanism based on comparison results between the point density currently calculated and the point density last calculated to thereby adjust the focal point toward the in-focus position. In another aspect, an imaging device having an autofocus function can be provided without using event data.