Image Processing Device Focal Range Control Depth Measurement
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Solution Overview
Problem
Existing depth measurement techniques using the passive method, such as Depth from Defocus (DFD), face challenges in accurately distinguishing between lens focus blur and inherent image blur, and require either increased sensitivity or longer exposure times, leading to noise or reduced light, which affects measurement accuracy.
Innovation Solution
An image processing apparatus and method that extend the depth of field by controlling the focal range without stopping down the aperture or using masks, allowing stable distance measurement using a small number of images, through focal position changes during exposure, and utilizing wavefront modulation elements or multifocal lenses to modulate light beams, enabling continuous or discontinuous focal ranges for easier blur measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a mask with special structure is inserted into the aperture to create periodic zero points in spatial frequency spectrum, then distance measurement capability is improved, but amount of incident light decreases causing increased noise or blur
Solution Approach 1:
The patent removes the mask component from the optical system entirely. Instead of using a mask to create periodic zero points in the spatial frequency spectrum, the invention uses natural optical phenomena and image processing techniques to achieve depth measurement without the light-blocking mask structure.
Solution Approach 2:
The patent changes the approach from modifying the optical path with a mask to modifying image processing parameters. It uses focus variation across multiple images and spectral analysis in the frequency domain to extract depth information without physically altering the aperture or light path.
2Stability of the object's composition
If aperture is significantly stopped down to obtain reference image with small number of images, then depth of field is extended, but amount of incident light decreases affecting measurement accuracy
Solution Approach 1:
The patent employs dynamic focus adjustment where the lens focus position is varied across multiple image captures. By taking images at different focal positions and combining them through image processing, the system achieves extended depth of field without requiring aperture stopping down, thus maintaining adequate light levels.
Solution Approach 2:
The patent continuously varies the focus position across multiple image captures rather than using a fixed aperture setting. This continuous focus variation allows the system to gather depth information across different depth ranges while maintaining consistent light levels throughout the imaging process.
3Loss of time
If increase sensitivity of imaging device to compensate for decreased light, then exposure time can be reduced, but noise of captured image increases
Solution Approach 1:
The patent combines multiple images captured at different focus positions to create the final depth map. By merging information from multiple images with adequate exposure times, the system achieves accurate depth measurement without requiring excessively high sensitivity that would introduce noise in single-image capture.
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
This approach enables high-accuracy distance measurement over a wide range using fewer images, reducing noise and light quantity issues, while maintaining image quality and accuracy, by generating a uniform blur pattern that can be easily measured using the DFD algorithm.
Implementation Method 1
The imaging unit includes a wavefront modulation element which is located in an optical path from the subject to the imaging unit and modulates a wavefront of a light beam
Implementation Method 2
a multifocal lens which is located in an optical path from the subject to the imaging unit and has a plurality of focuses such that the focal range of the image captured by the imaging unit is approximately continuous
Implementation Method 3
an imaging unit including: a lens unit; and an imaging device
Data Source
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AI summary
An image processing apparatus (10) includes: an imaging unit (11) which captures an image; a focal range control unit (12) which extends a focal position and a depth of field of a captured image by controlling an imaging device or a focus lens in the imaging unit (11); and a distance measurement unit (14) which measures a distance to a subject, from a degree of blur in each of n images (where n ≥ 2) captured by the imaging unit (11) controlled by the focal range control unit (12) and having focal ranges different from each other.